WO2003060940A1

WO2003060940A1 - Micro-electromechanical system and method for production thereof

Info

Publication number: WO2003060940A1
Application number: PCT/CH2002/000722
Authority: WO
Inventors: Ralf Strümpler
Original assignee: Abb Research Ltd
Priority date: 2002-01-18
Filing date: 2002-12-23
Publication date: 2003-07-24
Also published as: EP1468436A1; EP1468436B1; ATE304736T1; EP1357571A1; AU2002361920A1

Abstract

The invention relates to a micro-electromechanical system comprising a substrate (S) and at least two micro-elements (1, 2), of which a first one is a switchable bistable. The micro-elements (1, 2) comprise surfaces (3a, 4a) facing each other, generated by means of a structuring method and with a minimum separation characteristic for the structuring method. The first micro-element (1) is then switched to the other stable state (B), whereupon the separation between the surfaces (3a, 4a) facing each other is smaller than the minimal separation characteristic for the structuring method. The micro-electromechanical system can be embodied as an electrostatically operated micro-switch with improved switching. Laterally and horizontally working micro-electromechanical systems with new functionality and relays with current-free closing can be produced.

Description

MICROELECTROMECHANICAL SYSTEM AND METHOD FOR THE PRODUCTION THEREOF

DESCRIPTION

Technical field

The invention relates to the field of micro-electromechanical systems, in particular

- On a micro-electromechanical system according to the preamble of claim 1 and

- On a method for producing a micro-electromechanical system according to the preamble of claim 21.

State of the art

Such a micro-electromechanical system (micro electro-mechanical system, MEMS) forming the preamble of claims 1 and 21 and a corresponding method are known for example from DE 198 00 189 AI. There, a micromechanical switch is described, which comprises a flat carrier substrate, a contact piece fixed on the carrier substrate, a movable electrode and a counter electrode fixedly connected to the carrier substrate. The mobile electrical i & has a free end and a fixed end connected to the carrier substrate. The movable electrode and the counter electrode have surfaces facing one another. By electrostatic attractive forces between these mutually facing surfaces, the movable electrode can be bent, that is to say elastically deformed, in such a way that the free end of the movable electrode approaches the counterelectrode and thereby also the contact piece until there is contact between the free end of the movable electrode and the contact piece comes. The movement of the free end of the movable electrode takes place laterally, that is to say parallel to the flat carrier substrate.

The electrostatic attractive forces between the facing surfaces of the movable electrode and the counter electrode are generated by the application of a voltage between the movable electrode and the counter electrode. In order to avoid a short circuit, that is to say an electrical contact between the movable electrode and the counter electrode, stoppers are introduced into the counter electrode which protrude beyond the surface of the counter electrode facing the movable electrode and are not at the same potential as the counter electrode. For the same purpose, springs can also be provided, which are attached to the side of the movable electrode facing away from the counter electrode and restrict the movement of the movable electrode in the direction of the counter electrode. In addition, the surface of the movable electrode facing the counter electrode can also be provided with an electrically insulating layer for the same purpose.

The electrostatic attraction force F between two parallel surfaces of the surface A at a distance d when a switching voltage U is applied between the two surfaces is given by

The force increases linearly with the surface, quadratically with the tension and inversely proportional to the square of the distance.

The microsystem disclosed in the aforementioned DE 198 00 189 AI was generated from the carrier substrate using a deep silicon etching process. After a mask has been applied to the carrier substrate, material is etched out of the carrier substrate at the locations at which the mask is opened. This creates trenches or etching channels that have at least one minimum width that is characteristic of the etching process.

In order to achieve mobility of the free end of the movable electrode, a sacrificial layer process is used which separates the free end of the movable electrode from the carrier substrate. For this purpose, a sacrificial layer arranged in the carrier substrate below the movable parts of the micromechanical switch is selectively removed by an etching process, the sacrificial layer at locations where a connection to the substrate is desired, such as at the counter electrode, the fixed contact piece and the fixed end of the movable electrode , persists.

DE 42 05 029 CI shows an electrostatically operated micro-electro-mechanical relay that works horizontally. That means the switching movement of this relay is essentially perpendicular to a carrier substrate. A tongue-shaped electrode with a contact piece is etched free from a silicon substrate. The substrate is then applied to a counter substrate with a counter electrode and a counter contact in such a way that the electrode includes a wedge-shaped gap with the counter electrode. By applying a switching voltage between the electrode and the counter electrode, these can be moved towards one another, whereby an electrically conductive connection between the contact and counter contact can be achieved. Large contact forces can be achieved using relatively wide electrodes. DE 197 36 674 CI also discloses a micro-electromechanical relay and a method for its production, which operates horizontally. A movable contact is attached to an anchor tongue which is attached to a substrate on one side and which is bent away from the substrate in the idle state. To generate a high contact force, this contact interacts with a fixed contact, which is attached to a spring tongue that is also curved away from the substrate. The curvature of the contacts is achieved by applying a tension layer on both contacts. Achieving a high reproducibility of a curvature of the contacts produced in this way and thus the contact spacings in the idle state (open) is not easy in terms of production technology.

US 5,638,946 and US 6,057,520 describe further horizontally operating MEMS switches.

J. Qiu et al., "A Centrally-Clamped Parallel-Beam Bistable MEMS Mechanism", Proc. of MEMS 2001, Interlaken, Switzerland, Jan. 20-22, 2001, shows a bistable switchable micro-electromechanical mechanism. This consists of two parallel spring tongues or membranes suspended on both sides, which describe a cosine course. The spring tongues are connected to one another in the middle and are fastened to a carrier substrate at their ends. This bistable micro-element is generated from the silicon carrier substrate by means of ion etching and sacrificial layer technology, so that the spring tongues are laterally movable and two stable states are shown. By applying a perpendicular ^¬ derzungen to the Fe and directed parallel to the carrier substrate force of the bistable mechanism is switched between the two stable states and herschaltbar, wherein the respective mirror-image to the initial position end ^¬ position by snapping the mechanism finally independently ER- is enough. In order to achieve elastic mobility and mechanical stability of the micro-element on the one hand, the 3 mm long spring tongues are only 10 μm to 20 μm wide, but 480 μm high.

Further laterally movable micro-electromechanical mechanisms are described in M. Taher, A. Saif, "On a Tunable Bistable MEMS - Theory and Experiment", Journal of Microelectromechanical Systems, Vol. 9, 1 57-170 Ouni 2000).

US Pat. No. 5,677,823 discloses an electrostatically switchable bistable storage element which operates horizontally. A bridge-like movable contact aligned essentially parallel to a carrier substrate is arranged above a fixed contact which is fixedly connected to the carrier substrate. At both ends, the movable contact is fixed to the carrier substrate, while it bulges away from the carrier substrate in the middle (first stable position) or bulges in the direction of the carrier substrate (second stable position). In the second stable position, the movable contact and the fixed contact touch: the switch is closed. The switch is open in the first stable position. The bistability of the switch results from mechanical stresses which are introduced into the movable contact during manufacture of the switch. Also below the movable contact, two electrodes are arranged on the side next to the fixed contact. By applying electrical voltages to the movable contact and to these electrodes, the contact and electrodes can be electrically charged, so that electrostatic attraction or repulsion forces result between them, by means of which the switch can be switched back and forth between the two stable positions. Another horizontally operating bistable MEMS mechanism is described in Sun et al., "A Bistable Microrelay Based on Two-Segment Multimorph Cantilever Actuators", IEEE Catalog No. 98CH36176.

Presentation of the invention

It is therefore an object of the invention to provide a micro-electro-mechanical system (MEMS) of the type mentioned at the outset, which enables a more flexible MEMS design. In particular, improved switchability and new functionalities are to be made possible. This task is solved by a MEMS with the features of claim 1.

Furthermore, it is an object of the invention to provide an improved method for producing MEMS. This object is achieved by a method having the features of claim 21.

Improved ability to switch, for example, mean that a Schaltvor ^¬ gear even at low switching voltages be triggered. New functionalities can mean, for example, the realization of voltage-free closed connections or of micro-relays with voltage-free opened as well as voltage-free closed connections.

The MEMS according to the invention comprises a substrate and a first micro-element and a second micro-element, wherein

the first micro-element and the second micro-element are connected to the substrate,

- the first micro-element having a first surface and the second micro ^¬ element has a second surface, which surfaces face each other and are generated by a patterning process, - The first micro-element contains a switching part by which it can be switched bistably between an initial position and a working position, and

- The distance between the first surface and the second surface in the working position of the first micro-element is smaller than a minimum distance between the first surface and the second surface that can be generated by the structuring method.

A first micro-element, which can be switched between the two stable positions initial position and working position, is used in connection with a second micro-element in such a way that the first micro-element, after switching from the initial position to the working position, has a smaller distance from the second micro - Element has as in the initial position. Both micro-elements are connected to the substrate and produced using a structuring process. According to the invention, the aforementioned smaller distance in the working position is smaller than a minimum distance, which is characteristic of the structuring method, between the two micro-elements.

In this way it is achieved that new degrees of freedom are obtained in the design of MEMS, since process-related boundary conditions are overcome. A wide variety of micro-actuators can be realized in a new or simpler way or in an improved form.

In a preferred embodiment of the subject invention, the second micro-element is a firmly connected to the substrate first fe ^¬ Stes end and a movable part, whereby in the working position of the first micro-element, the movable part of the second micro-element by electrostatic forces between the first micro-element and the second micro-element can be moved from a switch-off position to a switch-on position, and the two micro-elements in the area of the point which has the aforementioned smaller distance between the two micro-elements, has contact points and is electrically non-conductive. The fact that there are points of contact means that the smaller distance mentioned is zero.

This makes it possible to manufacture electrostatically operating actuators whose electrostatically switchable electrodes (electrode and counter electrode) touch each other. The small or vanishing electrode spacings achieved as a result have improved switchability. Switching the actuator with very low switching voltages is possible.

In a further advantageous embodiment of the subject matter of the invention, the first micro-element is additionally designed in such a way that it contains an adapted counter-electrode which is adapted to the shape of the second micro-element: The adapted counter-electrode is shaped in such a way that in the switch-on position of the second micro-element overlap the adapted counterelectrode and the second micro-element over a large area in the area of the mentioned contact points. In the switch-on position of the second micro element, the matched counter electrode and the second micro element nestle against one another. This maximizes the areas between which the electrostatic attractive forces act, which results in greater electrostatic attractive forces and thus improved switchability. Switching the actuator at very low switching voltages is made possible.

In a further advantageous embodiment, the adapted counter-electrode additionally comprises a second section, which is set back in a step-like manner with respect to the section of the counter-electrode that clings to the second micro-element. In the switch-on position of the second micro-element, this second section of the connected fit counter electrode and the second micro-element a gap. In this way, a force which the second micro-element is able to exert in its switch-on position can be tailored and very large by dimensioning the length, width and height of the gap accordingly. The force that can be selected in this way can be, for example, a contact force of the second micro-element on one or two electrical contacts, which contacts the second micro-element in its switched-on position, thereby making a reliable electrical contact.

In a further preferred embodiment, a changeover switching relay is implemented.

In other advantageous embodiments of the subject matter of the invention, relays or changeover relays are implemented with voltage-free closed connections.

In particular, in a preferred embodiment, the movable part of the second micro-element can be elastically deformed by switching the first micro-element from the initial position into the working position. This makes it possible to implement closed connections without voltage.

After the structuring of two micro-elements with mutually facing surfaces, the method according to the invention includes switching the bistable switchable micro-element. This enables new or improved MEMS such as those mentioned above to be manufactured.

Other preferred embodiments are described and the figures from the dependent patent claims ^¬. Brief description of the drawings

The subject matter of the invention is explained in more detail below on the basis of preferred exemplary embodiments which are illustrated in the accompanying drawings. Show it:

Figure 1 is a schematic representation of a MEMS according to the invention with a cosine-shaped bistable element, in supervision.

FIG. 2 shows a schematic illustration of a MEMS according to the invention with a bistable element in the form of an antinode, in supervision; FIG.

3 shows a schematic illustration of a MEMS according to the invention with a cosine-shaped bistable element and a matched counter electrode, in supervision;

4 shows a schematic illustration of a micro-relay according to the invention with a cosine-shaped bistable element and a matched counter electrode, in supervision;

5 shows a schematic illustration of a micro changeover switching relay according to the invention with two cosine-shaped bistable elements and an adapted counter electrode, in supervision;

6 shows a schematic representation of a micro-relay according to the invention with a cosine-shaped bistable element and a stepped counter electrode, in supervision;

Figure 7 is a schematic representation of an inventive micro-relay with kosinusförmigem bistable element and gestuf ^¬ ter counter electrode and two-movable part of the second micro-element, in a plan view.

Fig. 8 is a schematic representation of an inventive

Two-way switching relay with monostable second micro element and NO and NC connections, under supervision; Fig. 9 is a schematic representation of an inventive

Two-way switching relay with bistable second micro-element and NO and NC connections, under supervision;

10a shows a schematic representation of a micro relay according to the invention with an NC connection, state: first micro element in initial position; under supervision;

10b shows a schematic representation of a micro relay according to the invention with an NC connection, state: first micro element in the working position, second micro element in the off position; under supervision;

10c shows a schematic representation of a micro-relay according to the invention with an NC connection, state: first micro-element in the working position, second micro-element in the switch-on position; under supervision;

Figure 1 1 a is a schematic representation of a horizontally operating micro-relay according to the invention with NC connection, sectional side view;

Fig. 1 1 b is a schematic representation of a horizontally operating micro-relay according to the invention with NC connection, in supervision;

The reference symbols used in the drawings and their meaning are summarized in the list of reference symbols. In principle, parts that have the same effect are provided with the same reference symbols in the figures.

Ways of Carrying Out the Invention

1 shows a schematic plan view of a first micro-electromechanical system (MEMS) according to the invention. It includes a first mi Kro element 1 and a second micro element 2, both of which are rigidly connected to a substrate S.

The substrate s is a wafer made of single-crystal silicon, in which one of the two largest surfaces forms a main surface of the substrate. In Fig. 1, this main surface lies in the paper plane. The first micro-element 1 and the second micro-element 2 were formed from the substrate S using ion deep etching (DRIE, dry reactive ion etching) and sacrificial layer technology.

The structuring process DRIE has the property of being a material-removing process; it is an etching process. It also has the property of being well suited for producing narrow yet deep channels, columns or trenches, as a result of which the DRIE can be given a preferred direction which indicates the direction of the preferred material removal and is therefore perpendicular to the main surface of the substrate. Again perpendicular to this preferred direction, the width of a trench created by DRIE is limited downwards, that is to say narrow trenches. This means that there is a minimum trench width that can be generated by the structuring method (for example DRIE). There is therefore a minimum distance for the two surfaces which form the lateral boundaries of such a trench. Details of how the micro-elements 1, 2 can be formed from the substrate by means of ion etching and sacrificial cutting technology are known to the person skilled in the art and can also be found, for example, in the aforementioned publication DE 198 00 189 AI, which hereby includes the entire disclosure content in the Description is included.

Micro-elements produced by DRIE typically have side surfaces that are aligned almost perpendicular to the main surface of the substrate S, or in other words: (Local) surface normal vectors of the side surfaces run practically parallel to the main surface of the substrate S. Such micro-elements thus essentially have the shape of a straight (right-angled) prism, the base of which is aligned parallel to the main surface of the substrate S. In addition, the height of such a micro-element (perpendicular to the main surface) is typically very large compared to the (narrowest) width of such a micro-element. The first micro element and the second micro element are of this type.

The first micro-element 1 is designed as a bistable elastic MEMS mechanism, as described in the publication J. Qiu et al., "A Centrally-Clamped Parallel-Beam Bistable MEMS Mechanism", Proc. of MEMS 2001, Interlaken, Switzerland, Jan. 20-22, 2001. Details on design forms, properties and on the production of such a micro-element can be found in this publication, which hereby includes the entire disclosure content in the description. The first micro-element 1 is fixed on the substrate S at a first end 6 and a second end 7. In between, the first micro-element 1 has two parallel, cosine-shaped spring tongues which are connected to one another in the middle 8 between the two ends 6, 7. In view of their small width and large height (perpendicular to the main substrate surface), these spring tongues can also be regarded as a parallel membrane.

The first micro-element 1 can be switched bistably between an initial position A and a working position B (the latter shown in dashed lines in FIG. 1). That is, the micro-element 1 has two mechanically stable states or positions A and B between which it by applying a la ^¬ eral, so power substrate parallel movable to and fro; the movement takes place essentially laterally. Possible intermediate positions NENs are not stable, but instead lead independently to a rapid transition to one of the two stable states A or B. The transition takes place by preferably elastic deformation of the first micro-element 1. The first micro-element 1 here therefore consists only of a switching part 5 through which it can be switched bistably.

The first micro-element 1 has on the side facing the second micro-element 2 a side surface shaped by DRIE, which is referred to as the first surface 3a. This first surface 3a has a first coating 3b, which is electrically insulating and whose outer surface, that is to say facing away from the first surface 3a, forms the first surface 3 of the first micro-element 1. The first coating 3b is typically produced by oxidation of the silicon.

The second micro-element 2 comprises a first fixed end 10, at which it is fixed on the substrate s, and a movable part 11; it is arranged adjacent to the first micro element 1. On that side of the second micro-element which faces the first micro-element 1, the second micro-element 2 has a side surface shaped by DRIE, which is referred to as the second surface 4a. This second surface 4a has a second coating 4b which is electrically insulating and whose outer surface, that is to say facing away from the second surface 4a, forms the second surface 4 of the second micro-element 2. The first upper ^¬ surface 3 and the second surface 4 are facing surfaces, as well as the first surface 3a and the second surface 4a facing each other. The second coating 4b is also typically Oxida ^¬ tion of the silicon produced.

After shaping the first surface 3a and the second surface 4a by means of DRIE, the first micro-element 1 is in the initial position A and that second micro-element 2 in an off position A '. Since the surfaces 3a and 4a are formed in the middle of DRIE, they are at a distance from one another which is at least as large as a minimum distance given by DRIE. The spacing of the surfaces from one another means the distance between the two points closest to one another, the one point lying on the first surface 3a and the other point lying on the second surface 4a. The distance is therefore the width of the trench between the first surface 3a and the second surface 4a at its narrowest point. In Fig. 1, this point is at a corner of the first fixed end 10 of the second micro-element 2 and near the first end 6 of the first micro-element 1 on the membrane of the first micro-element 1, which has the first surface 3a.

The initial position A of the first micro-element 1 is a production-related starting position. The arrangement of the first micro-element 1 and the second micro-element 2 is selected such that after the first micro-element 1 has been switched from the initial position A to the working position B, the distance between the first surface 3a and the second surface 4a is smaller than the minimum distance given by the manufacturing process (e.g. DRIE). In the MEMS in FIG. 1, the distance is even zero, that is, in the working position A, the first micro-element 1 and the second micro-element 2 touch. In the working position A, the intended interaction of the first micro-element 1 with the second micro element 2 take place within the MEMS.

The MEMS in FIG. 1 represents a micro-actuator, which is formed by the first micro-element 1 and the second micro-element 2, together with the substrate S. The second micro element 2 acts as a movable, electrostatically switchable electrode and the bistable switchable first micro ^¬ element 1 as an associated electrostatic counter electrode. The first micro-element 1 is in the working position A. The mode of operation of the micro-actuator when it is in working position B is essentially known from the prior art: there is a contacting electrode C at the first fixed end 6 of the first micro-element 1 and at the first fixed end 10 of the second micro-element 2, a contacting electrode C is provided. These contacting electrodes C, C serve to apply switching voltages to the micro-elements 1, 2, by means of which the micro-elements become electrostatically charged, so that electrostatic forces act between the micro-elements 1 and 2. For this, the material from which the micro-elements are made must be sufficiently conductive, which is achieved, for example, by appropriate doping of the silicon. Due to the electrostatic forces between the micro-elements (more precisely: between the first surface 3 and the second surface 4), the movable part 11 of the second micro-element 2 can be moved from the switch-off position A 'to a switch-on position B ^{1 of} the second micro-element 2. The switch-on position B ¹ is shown in dashed lines in FIG. 1. In the MEMS in Fig. 1, an opposite charge of the micro-elements 1, 2 and thus an attractive electrostatic force is provided. To switch the second micro-element 2 back to the switch-off position A ¹ , the charges of the micro-elements 1, 2 are reduced. The fact that no undesired discharges take place, especially when the micro-elements 1, 2 touch, is achieved by the non-conductive coatings 3b, 4b.

As can be seen from equation (1), the electrostatic force decreases inversely proportional to the distance. The MEMS according to the invention from FIG. 1 thus has the great advantage of being able to be switched with even lower switching voltages than would be required for a MEMS whose distance between the electrode and counterelectrode is greater than or equal to the minimum distance given by the structuring method. The micro-actuator in FIG. 1 can be used, for example, as an optical micro-switch, in that a light beam to be switched is transmitted or is interrupted by the movable part 11 of the second micro-element 2, depending on whether the second micro-element is 2 is in the switch-off position A 'or in the switch-on position B ¹ . It is equally possible to deflect a light beam with the micro-actuator in FIG. 1, for example if a reflecting area is arranged in the movable part 11 of the second micro-element 2 (not shown). The switch-on position B ¹ is by definition present when there are suitable switching voltages; otherwise the switch-off position A 'is present.

The bistable switchable first micro-element 1 is used as an electrostatic electrode or counter electrode.

The embodiment in Fig. 1 has been described in great detail. For reasons of clarity and clarity, some of the details of the functioning of the MEMS according to the invention, which should now have become clear to the person skilled in the art, are no longer mentioned in the following.

FIG. 2 shows a MEMS which largely corresponds to the MEMS from FIG. 1; al ^¬ lerdings is the first micro-element 1 structured differently. The first micro-element 1 is here designed as another lateral, bistable and preferably elastically switchable mechanism. The first micro-element 1 is also fixed here on the substrate s at a first end 6 and a second end 7. Therebetween, the first micro-element 1 but a ge ^¬ curved spring tongue, which has the shape of an antinode. In view of its small width and great height (perpendicular to the The main surface of the substrate) can also be called this spring tongue as a membrane.

In the initial position A, that is, in the state in which the first micro-element 1 is structured, the first micro-element 1 describes a symmetrical antinode, in the working position B an asymmetrical antinode (the latter shown in dashed lines in FIG. 2). The asymmetrical antinode represents the second stable position of the first micro-element 1 and comes about because a stop firmly connected to the substrate S touches the first micro-element 1 in the working position B and leads to the corresponding deformation of the first micro-element 1 leads. This stop is formed here by an appropriately designed and arranged first fixed end 10 of the second micro-element 2. The corresponding point of contact is expediently to the right of a connecting section which runs from the second end 7 to the first end 6 of the first micro-element 1 if the symmetrical antinode is arranged in the initial position A to the left of this connecting section. The value of a position coordinate of the point of contact parallel to this connection path is not 0.5 (no asymmetrical antinode) and is preferably between 0.52 and 0.92 of the length of the connection path; here it is about 0.84. The stop can also be formed by a correspondingly shaped first end 6 or second end 7 of the first micro-element 1 or as a stop which is fixed separately on the substrate S (which is then to be regarded as belonging to the first micro-element 1).

As in the embodiment of FIG. 1, the bistable micro-element 1 is generated (structured) in the initial position A, the distance between the first micro-element 1 and the second micro-element 2 being at least as great as that given by the structuring method Minimalab- stood (between these micro-elements 1, 2). In the course of the production of the MEMS, after the application of coatings 3b, 4b, the first micro-element 1 is switched from the initial position A to the working position B, the distance between the two micro-elements 1, 2 being smaller in the working position B. the specified minimum distance. In the MEMS, two micro elements are therefore realized with a small distance from one another that cannot be produced by the structuring method (by utilizing the bistable switchability of one of the micro elements). For further details on the embodiment of FIG. 2, reference is made to that written in connection with FIG. 1.

FIG. 3 shows a MEMS according to the invention, which largely corresponds to the exemplary embodiment shown in FIG. 1; However, here the first micro-element 1 does not only consist of a switching part 5, but additionally comprises an electrode 9. The electrode 9 has an elongated part, which has the first surface 3a, the first coating 3b and the first surface 3 of the first Micro-element 1 includes. This part is connected by means of another elongated member that is approximately perpendicular to said tet be rich ^¬ to the switching portion 5 in the middle 8 between the ends 6,7 of the first micro-element. 1

Since the electrode 9 is attached to the switching part 5, it moves with the switching part 5 when switching from the initial position A to the working position B (and possibly back again). Are electrostatic by applying appropriate switching voltages attractive forces between the first micro-element 1 is generated (of course, in the working position A) and the second Mi ^¬ kro element 2, the movable member 1 1 ^¬ of the second micro-element 2 is elastically deformed and approaches the electrode 9: It is switched from the switch-off position A 'to the switch-on position B'. The shape of the electrode 9, and in particular the shape of the first surface 3, is preferably shaped in such a way that the first surface 3 and the second surface 4 are in full contact in the switch-on position. This means that there is a two-dimensional contact between the two surfaces 3, 4, which does not mean that the two surfaces 3, 4 have to touch completely. The first surface 3 is therefore adapted to the shape of the second surface 4 in the switch-on position. The two surfaces 3, 4 are nestled together in the switch-on position B '. Such an electrode 9 can be referred to as an adapted electrode 9. The adapted electrode 9 maximizes the area effective for the electrostatic forces and minimizes the effective distances. As a result, switching can take place even at low switching voltages. For further details on the embodiment of FIG. 3, reference is made to that written in connection with FIG. 1.

4 shows a MEMS, which is a micro-relay. The exemplary embodiment largely corresponds to that of FIG. 3. It likewise comprises an (adapted) electrode 9 and a bistable, elastically switchable micro-element 1 which is configured in a cosine shape. In addition, the second micro-element 2, or more precisely: the movable part 11 of the second Micro-element 2, a contact area 16, which is electrically conductive. The contact region 16 is preferably arranged in the region of that end of the movable part 11 of the second micro-element 2 which does not adjoin the first fixed end 10 of the second micro-element 2. The contact area 16 forms part of a side surface of the second micro-element 2 and is preferably designed as a coating which is applied to the second micro-element 2 by means of vapor deposition or sputtering techniques.

Further, the MEMS comprises two fixed on the substrate S, elec trically conductive ^¬ Fixkontakte 1 7.18. The arrangement of the fixed contacts 17, 18 and the contact area 16 is selected in such a way that it is more suitable in the event of concerns Switching voltages on the first micro-element 1 and the second micro-element 2 (that is, in the switch-on position B 'of the second micro-element 2), the contact area 16 generates an electrically conductive connection between the fixed contact 17 and the fixed contact 18. In the switch-off state A ¹ , this is not the case. There is therefore an electrostatic micro-relay through which a connection formed by the fixed contacts 1, 7.1, 8 can be switched by means of the switching voltages.

It is very advantageous in this, but also in the embodiments discussed below, that the distance in the open state between the contact area 16 of the second micro-element 2 and the fixed contacts 1, 7.1, 8 can be selected and can be reproduced very well in terms of production technology.

In FIG. 4, the contact area 16 is arranged on the side of the second micro-element 2 which faces the first micro-element 1, that is to say on the side which also contains the surface 4. Attractive electrostatic forces between the first micro-element 1 and the second micro-element 2 can cause electrical contact between the fixed contacts 1, 7.1, 8.

It is also possible (not shown) to arrange the fixed contacts 17, 18 in such a way that they are located in that area of the substrate S which lies on the side of the second micro-element 2 facing away from the first micro-element 1. The contact region 16 is then correspondingly arranged on that side of the movable part 11 of the second micro-element 2 which faces away from the first micro-element 1. In this way, the relay can be switched by repulsive electrostatic forces. Of course, it is also possible to construct this micro-relay or the micro-relay shown in FIG. 4 without (adapted) electrode 9 (analogous to the construction in FIG. 1). 5 shows a micro changeover relay according to the invention. It contains all the features of such a MEMS, as was described in connection with FIG. 4. In addition, the MEMS also comprises a third micro-element T and two further fixed contacts 17 ', 18'; and the second micro-element 2 has a further electrically conductive contact area 6 ', which is arranged on a side of the movable part 11 of the second micro-element 2 which is opposite the side which has the contact area 16. The third micro-element 1 'and the further fixed contacts 1 7', 1 8 'are arranged with respect to the elongated movable part 11 of the second micro-element 2 in mirror image to the first micro-element 1 and the fixed contacts 1 7, 18. Of course, the arrangement does not have to be a mirror image; it suffices if the third micro-element T is connected to the substrate in a region of the substrate S which lies on the side of the second micro-element (2) facing away from the first micro-element 1 and the further fixed contacts 17 ', 18' are connected to the substrate in a region of the substrate S which is on the side of the second micro-element 2 facing away from the fixed contacts 1 7, 18. The structure of the third micro element T corresponds to the structure of the first micro element 1. The further fixed contacts 17 ', 18' are of the same design as the fixed contacts 17, 18.

The interaction between the third micro-element T and the second micro-element (2) and the further fixed contacts (1 7 ', 18') corresponds to the above-described interaction between the first micro-element 1 and the second micro-element 2 and the fixed contacts 1 7.1 8. When suitable switching voltages are applied to the third micro-element T and the second micro-element 2, an electrically conductive connection between the further fixed contacts 17 ', 18' can be created by the further contact area 16 '. Thus lies with this embodiment Three-position switch or a changeover relay in front that has three defined states: (1st) contacts between the two fixed contact pairs 17, 18; 1 7 ', 18' open, (2nd) contacts between the other fixed contacts 17 ', 18' open and contacts between the fixed contacts 1 7.1 8 closed and (3.) contacts between the fixed contacts 1 7.18 open and contacts between the further fixed contacts 1 7 ', 18' closed.

FIG. 6 shows a further MEMS according to the invention, which largely corresponds to the MEMS from FIG. 4. It contains the features of the MEMS from FIG. 4, for which reference is made to the corresponding part of the description. However, the electrode 9 of the first micro-element 1 is specially designed here. The electrode 9 has an (optionally step-shaped) recess. The electrode 9 comprises a gap-forming surface 12, which is set back in a step-like manner with respect to the first surface 3 of the first micro-element 1. This electrode 9 can be referred to as a stepped electrode 9. This MEMS uses attractive electrostatic forces to switch from the switch-off position A 'to the switch-on position B'. If the first micro-element 1 is in the working position B and the second micro-element 2 is in the switch-on position B ', the gap-forming surface 12 and the second micro-element 2, or more precisely: the movable part 11 of the second micro, close -Elementes 2, a gap 13 a. As a result, the size of a contact force that is exerted by the second micro-element 2 on the fixed contacts 1, 7.18 can be selected. In particular, a very good, reliable contact and a large contact force can be achieved. The choice of the geometry of the gap allows a targeted predetermination and choice of the contact force. In particular, the length of the gap and the width of the gap (ie the distance between the movable part 11 of the second micro-element 2 and the gap-forming surface 12) and, if appropriate, the course of the width of the gap can be selected for this purpose. Typically the length of the gap about an order of magnitude, preferably about two orders of magnitude larger than the width of the gap. A (roughly) uniformly wide gap is advantageously chosen, and the first surface 3 contacts the second surface 4 over the entire surface. The relative arrangement of the micro-elements 1, 2 and the fixed contacts 17, 18 on the substrate has to be done carefully.

Furthermore, such a MEMS has the advantage that any problems that occur when switching from the switch-on position B 'to the switch-off position A', which are caused by a slow or poor detachment of the movable part 11 of the second micro-element 2 from the electrode 9 (that is more precisely: can occur from the first surface 3), for example due to surface effects, can be reduced. The (air) gap 13 allows a rapid detachment of the movable part 11 of the second micro-element 2 from the electrode 9 when switching from the switch-on position B 'to the switch-off position A', while in the switch-on position B 'large electrostatic attractive forces between the first micro-element 1 and the second micro-element 2 act if the gap width has been chosen to be correspondingly small.

7 shows a further advantageous embodiment of the invention. It largely corresponds to the embodiment shown in FIG. 6 and is described on the basis thereof. The movable part 11 of the second micro element 2 is specially designed here. It has a first region 14 and a second region 15, the first region 14 being less rigid, that is to say more easily deformable, than the second region 15 and the first region is between the fixed first end 10 of the second micro Element 2 and the second region 1 5 arranged. The contact ^¬ region 16 is advantageously arranged in the second region 1 5, in particular in the area of the first region 1 5 opposite end of the second portion 16. Preferably, the second region 15 at least nevertheless that area of the movable part 1 1 in which the movable part 1 1 and the second micro-element 2 do not face each other. A (slight) overlap of the second region 15 with the region of the movable part 11 in which the movable part 11 and the second micro-element 2 face each other is particularly advantageous. In the exemplary embodiment shown in FIG. 7 with a stepped electrode 9, the second region 15 advantageously also comprises at least that region of the movable part 11 in which the movable part 11 and the gap-forming surface 12 face each other. In this case, it is particularly advantageous if the second region 15 also also has a (slight) overlap with the first surface 3. In the switched-on state B ', there is advantageously full-area contact between the first surface 3 and a part of the second surface 4, this part of the second surface 4 lying completely in the first region 14.

The greater stiffness of the second area 15 compared to the first area 14 is achieved in the exemplary embodiment from FIG. 7 in that the second area 15 is made thicker or wider than the first area 14. It is also possible for the second area 15 to be more difficult to bend to do, for example by applying a coating there; for example on a base of the straight prismatic body that forms the second region 15, or on at least one of the side surfaces. This could be achieved by means of a correspondingly (large, long) contact area which is designed as a coating.

The two differently stiff regions 14, ¹⁵ enable the second micro-element 2 to be switched from the switch-off position A 'to the switch-on position B' even at low switching voltages and attractive forces between the two micro ^¬ elements 1, 2; the movable part 1 1 (more precisely: the first region 14) of the second micro element 2 clings to the electrode 9, rolling, even with low attractive forces. This, while no or only a slight deformation of the second micro-element 2 is to be expected in the second area and preferably in the contact area 16. In this way, a secure electrical contact can be established by means of the contact area 16 between the fixed contacts 17, 18.

The features mentioned can of course also be applied analogously to the exemplary embodiments described above and to the exemplary embodiments described below (FIGS. 1 to 6 and 8 to 11 b).

8 shows a further advantageous embodiment of the invention, namely a two-way switching relay which, in addition to a normally open connection (NO connection), also additionally comprises a normally closed connection (NC connection). NO connection means that the connection is open when a suitable switching voltage is not applied (open when de-energized), as is the case in the exemplary embodiments listed above (FIGS. 4 to 7). NC terminals which are closed when not concern a suitable switching voltage (energized closed), however, are difficult to realize and are realized but in the ^¬ ser embodiment. In particular, an NC connection is implemented here in a MEMS structured using DRIE.

The MEMS in FIG. 8 is constructed in mirror image and includes a first Mi ^¬ kro element 1, a third micro-element T, a fourth micro-element 19 and a fifth micro-element 20, all of which are capable of bistable switching and ei ^¬ ne stable initial position a (drawn-through line) and have a stable Ar ^¬ beitsposition B (shown in phantom). They are designed here as bistable micro-elements of the type described in more detail in connection with FIG. 1 (two parallel, cosine-shaped, bound spring tongues). The position in which these micro-elements are structured by means of DRIE is the initial position A. The first micro-element 1 and the third micro-element T largely correspond to one another in their function. They consist of only one switching part 5. The fourth micro-element 19 and the fifth micro-element 20 likewise largely correspond to one another in their function. They each have a contacting electrode D, D '(for applying a signal to be switched, for example an electrical current) and an electrically conductive contact electrode 21, 22. The conductivity of the contact electrodes 21, 22 is preferably generated by a metallic coating. The contact electrodes 21, 22 are elongated, finger-shaped and fastened to the respective micro-element 19, 20 approximately in the middle 8 between the two ends of the respective micro-element 19, 20. Furthermore, the MEMS also has two fixed electrodes 17, 18 fixedly connected to the substrate S (for applying a further electrical current to be switched).

The MEMS in FIG. 8 further comprises a second micro-element 2. The second micro-element 2 is a monostable switchable micro-element; so it only has a stable position. It comprises a first fixed end 10 and a second fixed end 10 ', which ends 10, 10' are fixed on the substrate s, and a movable part 11 arranged between these two fixed ends 10, 10 '. The movable part 11 is formed as a, preferably ^¬ vibration-bellied, curved structure which is fastened to the two fixed ends 10, 10 'of the second micro-element 2 and has an electrically conductive contact area 16. The movable part 1 1 further comprises a second surface 4 which is formed by an optional second coating 4b, and which second Oberflä ^¬ surface 4 of a first surface 3 of the first micro-element 1 faces. The situation is similar with a fourth surface 4 'of the second micro-element 2 and a third surface 3' of the third micro-element V. The second surface 4 is arranged between the first fixed end 10 and the contact region 16. Analogously, the fourth surface 4 'is arranged between the second fixed end 10' and the contact area 16. After structuring of the second micro-element 2, the movable part 11 is in the switch-off position A ', the stable position of the second micro-element 2.

Due to the existence of the above-mentioned minimum distance between two micro-elements or surfaces generated by DRIE, the bistable micro-elements 1, 1 ', 19, 20 are spaced from the second micro-element 2 with at least one such minimum distance. After the application of the optional non-conductive coatings 3b, 3b 'of the first and third micro-elements 1, 1' and the optional electrically conductive coatings of the contact electrodes 21, 22, the bistable micro-elements 1, 1 ', 19, 20 switched from the initial position A to the working position B. As a result, the distance between the micro-elements or surfaces becomes smaller than the minimum distance mentioned; in Fig. 8 the micro-elements even touch. In particular, both contact electrodes 21, 22 touch the contact area 16. This creates an electrically conductive connection between the two contact electrodes 21, 22 and thus the NC connection. In this way, a voltage-free closed but detachable contact is realized. The surfaces 3, 4 and the surfaces 3 ″, 4 ′ also touch each other. As a result, only relatively low switching voltages can be applied between the second micro-element 2 and the first micro-element 1 and between the second micro-element 2 and the third micro Element T sufficiently large electrostatic attractive forces between the second micro-element 2 and the micro-elements 1, 1 'are generated, which for switching the second micro-element 2 from the switch-off position A' to the switch-on position B ' to lead. In the switch-on position B ', the NC connection is now open while the NO connection is closed. Due to its monostability, the second micro-element 2 automatically switches back to the switch-off position when a suitable switching voltage is not applied: NC connection closed, NO connection opened.

Numerous modifications of the embodiment of FIG. 8 are conceivable and advantageous: Here are a few examples:

- It is possible not to set up the MEMS with mirror symmetry.

- You can do without the fixed contacts 1 7.18 and then have an NC connection micro-relay.

- You can do without the micro elements 19, 20 and then have a NO connection micro relay.

If the fixed contacts 1 7.1 8 or the micro elements 1 9.20 are dispensed with, it is sufficient if the contact area 16 of the second micro element 2 is only electrically conductive on one side.

- The micro-elements 1, 1 'can be provided with (adapted, optionally: stepped) electrodes 9 (see FIGS. 3 to 7).

- The contacting electrodes 21, 22 can be designed differently; or do without them entirely and then contact the contact part 16 of the second micro-element 2 by means of the preferably electrically conductive coated switching part.

- It is possible to arrange the micro-elements 1, 1 'on the other side of the second micro-element 2, that is to say in the region of the substrate S which is on the side of the second micro-element 2 facing away from the fixed contacts 1, 7.1, 8 , Then the micro relay can be switched by electrostatic repulsive forces.

- It is also possible to arrange the first micro-element 1 in a different area (of the substrate S, with respect to the second micro-element 2) than the third micro-element 1 '. - You can do without the third micro-element T and only use the first micro-element 1 as an electrostatic counter electrode to the second micro-element 2 as a movable electrode. The features mentioned can be advantageous together or individually or in any combination.

9 shows a two-way switching relay which, in addition to a normally open connection (NO connection), also additionally comprises a normally closed connection (NC connection). The MEMS has a very similar structure to that described in FIG. 8; for corresponding features, reference is made to the text above. However, the second micro-element 2 is not monostable here, but rather bistable. In particular, it has a structure with two parallel, cosine-shaped spring tongues connected in the middle, as described in detail in connection with FIG. 1. The two stable positions of the second micro-element 2 are the switch-off position A 'and the switch-on position B'. A major advantage of the bistability of the second micro-element 2 is that no switching voltage is required to hold the second micro-element 2 in the switch-off position A 'or the switch-on position B'. After a suitable switching voltage has been applied and the switching operation caused thereby into the other state A ', B', the second micro-element 2 automatically remains in this state A ', B'. As a result, each of the two contact pairs on which a signal to be switched is present (fixed electrodes 17, 18 or micro elements 19, 20) can be an NO connection or an NC connection.

In addition, the MEMS in FIG. 9 has two further bistably switchable micro ^¬ elements: the sixth micro element 23 and the seventh micro ^¬ element 24. These are also constructed here with two parallel, cosine-shaped spring tongues connected in the middle and each have an (adapted) electrode 9. They are arranged in the area of the substrate S. net, which is on the side of the second micro-element 2 which faces away from the micro-elements 1, 1 '. The micro elements 23, 24 interact in an analogous manner with the second micro element 2 like the micro elements 1, 1 '. For this purpose, for example, the second micro-element 2 has a sixth surface 26a and an eighth surface 26a ', which have a fifth surface 25a (the sixth micro-element 23) and a seventh surface 25a' (the seventh micro-element 24). interact. By means of electrostatic attraction forces between the second micro-element 2 and the sixth micro-element 23 (more precisely: between the corresponding surfaces or surfaces) or the seventh micro-element 24 (more precisely: between the corresponding surfaces or surfaces), the second micro-element 2 can the switch-on state B 'are switched to the switch-off state A'.

Several advantageous modifications of this embodiment are conceivable:

- It is possible not to set up the MEMS with mirror symmetry.

- One can do without the fixed contacts 17, 18.

- You can do without the micro elements 19.20.

If the fixed contacts 1, 7.18 or the micro-elements 19, 20 are dispensed with, it is sufficient if the contact area 16 of the second micro-element 2 is only electrically conductive on one side.

- The micro elements 23, 24 can be used without adapted electrodes 9.

- The contacting electrodes of the micro elements 19, 20 can be designed differently; or dispense with them entirely and then contact the contact part 16 of the second micro-element 2 by means of the preferably electrically conductive coated switching part. - It is possible to switch the micro relay by electrostatic repulsive forces; or to switch it by means of electrostatic repulsive forces and electrostatic attractive forces.

- One, two or three of the micro-elements 1, 1 ', 23, 24 can be omitted; in particular to the diagonally opposite micro-elements 1, 24 or the micro-elements 1 ', 23.

If a switching process is generated by the interaction of at least two micro-elements 1, T, 23, 24 with the second micro-element 2, it is particularly advantageous if at least one of the corresponding switching voltages with a time delay relative to at least one of the other switching voltages is created. As a result, the movement which the movable part 11 of the second micro-element 2 makes during the switching process can be supported. In particular, the asymmetrical movement of the two parallel, cosine-shaped spring tongues of the second micro-element 2 can be carried out. Correspondingly adapted switching voltage profiles over time can also be used.

If, instead of a cosine-shaped bistable second micro-element 2, an antinode is used, the fixed contacts 1, 7, 8 or the fourth and / or fifth micro-element 19, 20 are advantageously arranged such that at least one of them is used for the asymmetrical design of the antinode.

The features mentioned can be advantageous together or individually or in any combination.

10a to 10c show a further advantageous embodiment of the invention in different positions. This MEMS is a micro relay with an NC connection, which is generally difficult to implement. The MEMS is starting from the Darge in Fig. 4 ^¬ presented embodiment described, since it is the same ingredients having. 10 a shows the MEMS, in the state it has after structuring by means of DRIE: the first micro element 1 is in the initial position A. FIG. 10 b shows the MEMS in a state in which the first micro Element 1 is in the working position B, and the second micro-element 2 is in the off state A '. 10c shows the MEMS in a state in which the first micro-element 1 is in the working position B and the second micro-element 2 is in the switched-on state B '.

In contrast to the embodiments discussed above, it is the case here that the first micro-element 1 after switching from the initial position A to the working position B does not simply come closer to the second micro-element 2 than the minimum distance given by DRIE and the second micro -Element 2 only touches (lightly). Rather, the arrangement of the micro-elements 1, 2 on the substrate s and the configuration of the micro-elements 1, 2 is selected such that the first micro-element 1 in the working position B exerts a force on the movable part 11 of the second MicroElementes 2, which leads to a (clear) elastic deformation of the movable part 1 1 of the second micro-element 2 (see Fig. 10b). The movable part 11 of the second micro-element 2 is deformed in such a way that the electrically conductive contact area 16 of the second micro-element 2 conductively connects the fixed contacts 17, 18: the NC connection is closed. A voltage-free closed but detachable contact is realized; in a MEMS structured using DRIE. In other words, by switching the first micro-element 1 from the initial position A to B Arbeitspositon a switching operation of the second micro ^¬ element 2 is caused. Since no switching voltage is required for this, the second micro-element 2 is in the switch-off position A \ after this switching operation. In order to open the NC connection again, a suitable switching voltage must be between the first micro-element 1 and the second micro-element 2 can be created. The NC connection is opened by means of electrostatic attractive forces, and the second microelement 2 goes into the switch-on state B '(see FIG. 10c).

In combination with features mentioned above, further advantageous embodiments can be created on the basis of FIGS. In particular, the electrode 9 can be omitted. Or the electrode 9 can be designed differently. In particular, one can advantageously design the electrode 9 and arrange the micro-elements 1, 2 relative to one another such that the points of contact between the two micro-elements 1, 2 (when the first micro-element 1 is in the working position A and the second micro- Element 2 in the switch-off position A 'is) essentially on a straight line with the center 8 in the initial position A and the center 8 in the working position. As a result, a low mechanical load on the first micro-element 1 can be achieved, and at the same time large contact forces can be exerted on the fixed contacts 1, 7.18 (secure contacts).

It is also advantageous, in analogy to the embodiment shown in FIG. 5, to provide a second pair of fixed contacts 17 ', 1 8' (not shown in FIG. 10), these fixed contacts 1 7 ', 1 8' being arranged in such a way that that the contact area 1 6 of the second micro-element 2 connects these fixed contacts 1 7 ', 18' to one another in an electrically conductive manner when the second micro-element 2 is in the switch-on position B '. Thus, similarly receives an alternating switching relay, which in FIG. 5, but with only a bistable Mi ^¬ kro element 1. Advantageously, moreover, the movable part 1 1 of the second micro-element 2 are formed in two parts (as in the embodiment of Fig. 7). Only laterally operating MEMS were discussed in the above explanations. However, it is also possible to construct the MEMS described (in a similar form) as horizontally operating MEMS. DRIE is typically not used for the production, but rather other methods known from MEMS or semiconductor technology are used, such as are mentioned, for example, in the already mentioned patents US Pat. No. 5,638,946, US Pat. No. 5,677,823 or DE 42 05 029 CI , The disclosure content of these patents is therefore hereby incorporated into the present description.

Fig. 1 1 a and Fig. 1 1 b show a possible embodiment in which the moving parts of the MEMS are essentially horizontally movable. Fig. 1 1 a is a sectional side view of the MEMS shown in supervision in Fig. 1 1 b. In Fig. 1 1 b with XIa-Xla the line of the section of Fig. 1 l a is shown. The MEMS is a micro relay with an NC connection.

The first micro-element 1 is designed here as a bistable, elastically switchable micro-element in the form of an antinode, analogous to the first micro-element 1 shown in FIG. 2. In the initial position A, the symmetrical antinode is arched away from the substrate S. The second end 7 of the first micro-element 1 is designed here as a bridge. As a result, the second micro-element 2 arranged below the antinode can extend to outside the area between the first end 6 and the second end 7 of the first micro-element 1. The first fixed end 10 of the second micro-element 2 serves here as a stop for the formation of the asymmetrical antinode of the first micro-element 1 in the working position B.

The movable part 11 of the second micro-element 2 initially runs (after the structuring) essentially parallel to the main surface of the Substrates S. After switching the first micro-element 1 from the initial position A to the working position B, the first micro-element 1 exerts a compressive force on the movable part 11 of the second micro-element 2. The second micro-element 2 is elastically deformed. It reaches its switch-off position A ', in which a movable contact electrode E fixedly attached to the movable part 11 contacts a fixed electrode 17 fixed on the substrate S. This creates an NC connection between the movable contact electrode E and the fixed electrode 17. This generation of an NC connection is quite analogous to the method described in connection with FIGS. 10a to 10c.

If suitable switching voltages are applied between the two micro-elements 1, 2, the second micro-element 2 changes to the switch-on state B ', in which the movable part 11 of the second micro-element 2 is bent away from the substrate and the NC connection is open , The contacting electrodes C, C are used to apply switching voltages. Contacting electrodes D, D 'are used to apply a signal to be switched. The contacting electrode D, which is electrically connected to the movable contact electrode E, is arranged here on the first fixed end 10 of the second micro-element 2. The contacting electrode D ′, which is electrically connected to the fixed contact 17, is arranged on the substrate S.

Other MEMS according to the invention, such as the MEMS described above, can also be implemented as horizontally operating MEMS.

An arrangement with a Fixelektrode 1 7 and a movable contact ^¬ lektrode E, as shown in Fig. 1, 1 a and 1 1 b, is also advantageous in the above MEMS described, which are described with a contact area 16 and two fixed electrodes 17, 18, can be implemented.

1 a a, b is that the distance in the open state between the movable contact electrode E of the second micro-element 2 and the fixed contact 17 can be selected and can be reproduced very well in terms of production technology. The same also applies to the embodiments discussed above, provided that they are carried out analogously to FIGS. 1 a, b with a movable contact electrode E.

A MEMS according to the invention can not only be implemented as a switch or relay, as in the examples above. A wide variety of micro-actuators can be implemented. For example, MEMS according to the invention can represent or actuate micro-valves or micro-pumps.

The substrate S used to produce a MEMS according to the invention is preferably flat. It typically has a main surface that is structured to produce the MEMS, the movement of the moving parts of the MEMS being movable essentially parallel or perpendicular to this main surface. Preferably, the substrate S from a semiconductor material, especially silicon, is the preferred way of monocrystalline ^¬ and particularly advantageous (for a sufficient electrical conductivity) also doped. When single-crystal silicon in under mechanical stress bistable switchable micro is ^¬ elements 1, 1 ', 2 1 9, 20, 23, 24 advantageously no or only very slowly SUC ^¬ constricting relaxation expected.

In particular, an SOI wafer (silicon-on-insulator) can be used which consists of three layers of silicon-silicon oxide-silicon which are parallel to the substrate. Since ^¬ at the silicon oxide layer serves as a sacrificial layer. The structuring method mentioned is typically a material-removing method, preferably an etching method. The LIGA technique or in particular the reactive ion etching and particularly advantageously the ion deep etching (DRIE) come into question here. The DRIE method has the advantage of being very well suited for the production of surfaces which are closely spaced (relative to their height perpendicular to the substrate) and are practically perpendicular to the main surface of the substrate S. DRIE is well suited for the production of laterally operating MEMS. However, methods which apply material are also conceivable, for example if surfaces facing one another in this way have a minimum distance as a result of the method. For example, rapid prototyping processes using photopolymerization.

In addition to actuators that can be actuated electrostatically, actuators that can be actuated electromagnetically or piezo-electrically can also be implemented according to the invention. The actuating forces can be repulsive or attractive.

A bistable micro-element according to the invention can also be tri-stable or otherwise multi-stable. It is for some appli ^¬ also not necessary applications that the micro-elements 1, 1, 19,20,23,24 are also 'after the first switch from the initial position A to working position B again zurückschalbar in the initial position A. One can also consider a one-time, for example plastic, deformation. The micro-elements 1, 1 ', 1 9, 20, 23, 24 but are preferably bistable ela ^¬ cally switchable and again zurückschaltbar in the initial position A. It is particularly advantageous to use the bistable micro-elements 1, 1 ', 2, 19, 20, 23, 24 as the described cosine-shaped or as the described oscillatory to form bulbous micro-elements, which can also be implemented in a modified form and combined within a MEMS.

Depending on the purpose, the micro elements can optionally be coated in an electrically conductive or electrically non-conductive manner. A non-conductive coating is preferably used to prevent discharges between electrostatic electrodes touching one another. For example, as an alternative or additional protection against such discharges, stoppers or springs can be used, as are known from DE 198 00 189 AI already cited. The contacting electrodes CC'.D.D 'can be produced in a known manner (for example by sputtering) and can be contacted for example by bonding.

Regarding the manufacturing process for the MEMS according to the invention, it should be noted that the first switching of the first micro-element 1 and also of the other bistable switchable micro-elements 1 ', 1 9, 20, 23, 24 from the initial position A to the working position B is still belongs to the manufacturing process of the MEMS. This initial switching process can take place mechanically. However, this switching operation is preferably carried out as part of a quality or functional test (burn-in) of the MEMS, it being possible for other units connected to the substrate to be tested or initialized in the process. The initial switching process can then preferably take place by generating an attractive force between the bistable micro-element 1, 1 ', 19, 20, 23, 24 and the second micro-element 2, this force advantageously being achieved by applying a switching voltage. Such a switching voltage is typically higher than a switching voltage that is used to switch the second micro-element 2 between the switch-off position A 'and the switch-on position B'. The features mentioned can be advantageous together or individually or in any combination.

The linear expansion of the MEMS described is typically between 0.2 mm and 5 mm, preferably 0.8 mm to 2 mm. For DRIE as a structuring method, the minimum distance mentioned (minimum trench width) is approximately 5 μm to 15 μm; it shows little dependence on the depth of the structured trench. The depth of the structured trench is typically 300 μm to 550 μm. By switching from the initial position A to the working position B, the corresponding distance is reduced to typically zero or 0.1 μm to 1 μm. Layer thicknesses of the electrically non-conductive coatings 3b, 3b ', 4b, 4b' are typically 50 nm to 500 nm

The switching voltages for the MEMS described (switching between switch-off position A 'and switch-on position B') are typically 10 V to 80 V, preferably 25 V to 50 V. When the first switching of the bistable micro-elements from the initial position A to the working position by electrostatic If there are attractive forces, switching voltages between 70 V and 300 V, preferably between 100 V and 200 V, are typically used for this.

LIST OF REFERENCE NUMBERS

1 first micro element T third micro element

2 second micro element

3 first surface (of the first micro-element); facing the second surface

3a first surface (of the first micro-element); facing the second surface

3b first coating (of the first surface)

3 'third surface (of the third micro-element); facing the fourth surface

3a 'third surface (of the third micro-element); facing the fourth surface

3b 'third coating (the third surface)

4 second surface (of the second micro-element); facing the first surface

4a second surface (of the second micro-element); facing the first surface

4b second coating (of the second surface)

4 'fourth surface (of the second micro-element); the third upper surface facing ^¬

4a 'fourth surface (of the second micro-element); ^facing the third surface

4b 'fourth coating (the fourth surface)

5 switching part of the first micro-element

6 first end of the first micro-element

7 second end of the first micro-element 8 middle between the first and the second end of the first micro-element

9 (adapted) electrode of the first micro-element

10 first fixed end of the second micro-element

10 'second fixed end of the second micro-element

1 1 movable part of the second micro-element

12 gap-forming surface

13 gap

14 first area of the movable part of the second micro-element

1 5 second area of the movable part of the second micro ^¬ element

16, 16 'contact area of the movable part of the second micro-element

17.18 fixed contacts

1 7 ', 1 8' fixed contacts

19 fourth micro element

20 fifth micro-element 21, 22 contact electrode

23 sixth micro element

24 seventh micro-element

25a fifth surface (of the sixth micro-element); facing the sixth surface

25a 'seventh surface (of the seventh micro-element); facing the eighth area

26a sixth surface (of the second micro-element); facing the fifth surface

26a 'eighth surface (of the second micro-element); facing the fifth surface

A Initial position

B working position A 'switch-off position (of the second micro-element)

B 'switch-on position (of the second micro-element)

C, C contacting electrodes

D, D 'contacting electrodes

E movable contact electrode (of the second micro-element)

S substrate

Claims

PATENT CLAIMS

1 . Micro-electromechanical system comprising a substrate (S) and a first micro-element (1) and a second micro-element (2), wherein

(a) the first micro-element (1) and the second micro-element (2) are connected to the substrate (S) and

(b) the first micro-element (1) has a first surface (3a) and the second micro-element (2) has a second surface (4a), which surfaces (3a, 4a) face each other and are produced by a structuring method are characterized by

(d) that the first micro-element (1) contains a switching part (5) by means of which it can be switched bistably between an initial position (A) and a working position (B), and

(e) that the distance between the first surface (3a) and the second surface (4a) in the working position (B) of the first micro-element (1) is smaller than a minimum distance that can be generated by the structuring method between the first surface (3a) and the second surface (4a).

2. Micro-electromechanical system according to claim 1, characterized by ^¬

(a) that the first micro-element (1) has a first surface (3) which is the same as the first surface (3a) or, if the first surface (3a) is provided with a first coating (3b), is the same Surface of this coating (3b), and

(b) that the second micro-element (2) has a second surface (4) on ^¬ which is equal to the second surface (4a) or if the second area- before (4a) is provided with a second coating (4b) is equal to the surface of this coating (4b).

3. Micro-electromechanical system according to claim 2, wherein

(a) the second micro-element (2) has a first fixed end (10) firmly connected to the substrate (S) and a movable part (1 1), characterized in that

(b) that the first surface (3) and the second surface (4) are electrically non-conductive, and

(c) that the first surface (3) and the second surface (4) have contact points in the working position (B), and

(d) that the second micro-element (2) can be switched from a switch-off position (A ') to a switch-on position (B') in that in the working position (B) of the first micro-element (1) the movable part (1 1) of the second micro element (2) can be moved between the first micro element (1) and the second micro element (2) by electrostatic forces.

4. Micro-electromechanical system according to claim 3, characterized in that

(a) that the first micro-element (1) comprises an electrode (9), which electrode (9) contains the first surface (3), and

(b) that the electrode (9) and the second micro-element (2) are designed such that in the switch-on position (B ') of the second micro-element (2) the first surface (3) and the second surface (4) touch completely.

5. Micro-electromechanical system according to claim 4, characterized in that the electrode (9) has a gap-forming surface (12) which is designed such that it is step-like with respect to the first surface (3) is set back and includes a gap (1 3) with the second micro-element (2) when the first micro-element (1) is in the working position (B) and the second micro-element (2) is in the switch-on position (B ') is located.

6. Micro-electromechanical system according to one of claims 3 to 5, characterized in that the movable part (1 1) of the second micro-element (2) has a first area (14) and a second area (1 5), wherein the first area (14)

- Is arranged between the second region (1 5) and the first fixed end (10) of the second micro-element (2),

- Part of the second surface (4), and

- Is less rigid than the second region (1 5).

7. Micro-electromechanical system according to one of claims 3 to 5, characterized in that

(a) that the micro-electromechanical system has two fixed contacts (17, 18) firmly connected to the substrate, and

(b) that the movable part (1 1) of the second micro-element (2) has an electrically conductive contact area (16),

- Which contact area (16) is arranged in the area of an end of the second micro-element (2) opposite the first fixed end (10) of the second micro-element (2), and

- Through which contact area (16) in the switch-on position (B ') of the second micro-element (2) the two fixed contacts (1, 7.1, 8) are conductively connected to one another.

8. Micro-electromechanical system according to claim 7, characterized by ge ^¬

(a) that the micro-electromechanical system is a third micro- Comprises element (l ¹ ),

- which is bistable switchable,

- Which is connected to the substrate (S), and

- Which is arranged in a region which is on the side of the second micro-element (2) facing away from the first micro-element (1), and

(b) that the micro-electromechanical system has two further fixed contacts (1 7 ', 18'), which further fixed contacts (1 7 ', 18') are firmly connected to the substrate (S) and are arranged in an area which on the side of the second micro-element (2) facing away from the fixed contacts (17, 1, 8),

(c) that the movable part (1 1) of the second micro-element (2) has a further electrically conductive contact area (16 '), which in the area of an end opposite the first fixed end (10) of the second micro-element (2) second micro-element (2), on the side of the second micro-element (2) facing away from the contact area (16), and

(d) wherein the third micro-element (V) interacts in an analogous manner with the second micro-element (2) and with the further fixed contacts (17 ', 18') like the first micro-element (1) with the second micro-element (2) and cooperates with the fixed contacts (1 7.1 8).

9. Micro-electromechanical system according to claim 6 and 7 or according to claim 6 and 8, characterized in that the contact area (16) in the second area (1 5) of the movable part (1 1) of the second micro-element (2) is arranged is.

10. Micro-electromechanical system according to claim 1, characterized by ^¬

(a) that the micro-electromechanical system is a third micro- Element (T) includes that

- Is connected to the substrate (S) and

- has a third surface (3a '),

(b) that the second micro-element (2) includes a switching part which

- a first fixed end (10) firmly connected to the substrate (S),

a second fixed end (10 ') firmly connected to the substrate (S),

- A movable part (11) arranged between these two fixed ends (10, 10 ')

- has a fourth surface (4a '), and

(c) by which switching part the second micro-element (2) can be switched between a switch-off position (A ') and a switch-on position (B ¹ ), whereby

(d) the movable part (1 1) of the second micro-element (2) comprises an electrically conductive contact area (16),

(e) the second surface (4a) is arranged between the first fixed end (10) and the contact region (16), and

(f) the fourth surface (4a ¹ ) is arranged between the second fixed end (10 ') and the contact area (16),

(g) the third surface (3a ') and the fourth surface (4a') are generated by the structuring method and face each other, and

(h) that the third micro-element (V) contains a switching part by which it can be switched bistably between an initial position (A) and a working position (B), and

(i) that the distance between the third surface (3a ') and the fourth surface (4a') in the working position (B) of the third micro-element (V) is smaller than a minimum distance between the third surface (3a ') and the fourth surface (4a').

1 1. Micro-electromechanical system according to claim 10, characterized in that

(a) that the third micro-element (V) has a third surface (3 ') which is equal to the third surface (3a ¹ ) or if the third surface (3a') is provided with a third coating (3b ') is equal to the surface of this coating (3b '), and

(b) that the second micro-element (2) has a fourth surface (4 ¹ ) which is equal to the fourth surface (4a ') or if the fourth surface (4a') is provided with a fourth coating (4b ¹ ) is equal to the surface of this coating (4b ').

12. Micro-electromechanical system according to claim 1 1, characterized in

(a) that the micro-electromechanical system contains two fixed contacts (17, 18) firmly connected to the substrate (S),

(b) that the second micro-element (2) can be switched from its switch-off position (A ') to its switch-on position (B') by the fact that in the working position (B) the first micro-element (1) and the third micro-element ( V) the movable part (1 1) of the second micro-element (2) by electrostatic forces between the first micro-element (1) and the second micro-element (2) and between the third micro-element (T) and the second micro -Element (2) is elastically movable, and

(c) that the second micro-element (2), the two Fixkontakte are (1 7,18) connected through the contact region (16) conductively connected ^¬ each other in the on position (B ^1).

1 3. micro-electromechanical system according to claim 12, characterized ge ^¬ ,

(a) that the micro-electromechanical system - A fourth micro element (19) and

comprises a fifth micro-element (20),

(b) which micro elements (19, 20)

are connected to the substrate (S) in a region which is on the side of the second micro-element (2) facing away from the fixed contacts (17, 18),

- Include switching parts by means of which they can be switched bistably between an initial position (A) and a working position (B), and

- Each have a contact electrode (21, 22) provided with an electrically conductive coating, and

(c) that in the switch-off position (A ') of the second micro-element (2) in the working position (B) of the fourth micro-element (19) and the fifth micro-element (20), the two contact electrodes (21, 22) are electrically conductively connected to one another through the contact region (16).

14. Micro-electromechanical system according to one of claims 10 to 13, characterized in that the second micro-element (2) can be switched bistably and elastically between its switch-off position (A ') and its switch-on position (B').

1 5. Micro-electromechanical system according to claim 14, characterized in that

(a) that the micro-electromechanical system

- A sixth micro element (23) and

- comprises a seventh micro-element (24),

(b) which micro elements (23, 24)

- are connected to the substrate (S),

- Are arranged on the side of the second micro-element (2) facing away from the second surface (4) and fourth surface (4 '), - include switching parts by means of which they can be switched bistably between an initial position (A) and a working position (B),

(c) that the sixth micro-element (23) has a fifth surface (25a),

(d) that the second micro-element (2) comprises a sixth surface (26a) which, on the side of the second micro-element (2) facing away from the second surface (4), between the first fixed end (10) and the contact area (16) is arranged,

(e) the fifth surface (25a) and the sixth surface (26a) facing each other and being produced by the structuring method,

(f) that the seventh micro-element (24) has a seventh surface (25a '),

(g) that the second micro-element (2) comprises an eighth surface (26a '), the side of the second micro-element (2) facing away from the fourth surface (4') between the second fixed end (10 ') and the contact area (16) is arranged,

(h) the seventh surface (25a ') and the eighth surface (26a') facing each other and being produced by the structuring method, and

(i) that the distance between the fifth surface (25a) and the sixth surface (26a) in the working position (B) of the sixth micro-element (23) is smaller than a minimum distance that can be generated by the structuring method between the fifth surface (25a) and the sixth surface (26a), and

(i) that the distance between the seventh surface (25a ') and the eighth surface (26a ") in the working position (B) of the seventh micro-element (24) is smaller than a minimum distance between the seventh surface (25a ') and the eighth surface (25a', 26a '), and 0) that the second micro-element (2) thereby from its switch-on position on (B ") can be switched into its switch-off position (A ') such that in the working position (B) of the sixth micro-element (23) and the seventh micro-element (24) the movable part (11) of the second micro-element ( 2) can be moved elastically by electrostatic forces between the sixth micro element (23) and the second micro element (2) and between the seventh micro element (24) and the second micro element (2).

16. Micro-electromechanical system according to one of claims 14 or 15, wherein

(a) the substrate (S) is designed as a flat solid with a main surface, and

(b) the micro-elements (1, 1 ', 2,19,20,23,24) are designed as straight prismatic bodies, the base surfaces of which are aligned parallel to the main surface, characterized in that

(c) that the movable part (1 1) of the second micro-element (2)

- is designed as a straight prismatic body and

- is laterally movable, and

(d) that the base of the straight prismatic body forming the movable part (1 1) either

- In the switch-off position (A ') the shape of a symmetrical antinode and

- In the switch-on position (B ") has the shape of an asymmetrical antinode, or

- Describes two parallel cosine-shaped lines which are connected to one another in the ^middle (8) between their two ends (6, 7).

1 7. Micro-electromechanical system according to one of claims 1 to 16, wherein (a) the substrate (S) is designed as a flat solid with a main surface, and

(b) the micro-elements (1, 1 ', 2, 19, 20, 23, 24) are designed as straight prismatic bodies, the base surfaces of which are aligned parallel to the main surface, characterized in that

(c) that there is at least one micro-element (1, 1 ", 2,19,20,23,24) switchable between an initial position (A) and a working position (B), the switching part of which

a first fixed end fixedly connected to the substrate (S),

- A second fixed end connected to the substrate (S) and

includes a movable part located between these two fixed ends,

(d) which moving part

- is designed as a straight prismatic body and

- is laterally movable, and

(e) that the base of the straight prismatic body forming the movable part is either

- In the switch-off position (A ') the shape of a symmetrical antinode and

- In the switch-on position (B ') has the shape of an asymmetrical antinode or

- describes two parallel cosine-shaped lines which are connected in the middle between their two ends.

8. Micro-electromechanical system according to claim 3, characterized ge ^¬ indicates that the movable part (1 1) of the second micro-element (2) by switching of the first micro-element (1) from the initial position A in the working position A is elastically deformable.

1 9. Micro-electromechanical system according to claim 1 8, characterized in that

(a) that the micro-electromechanical system has two fixed contacts (1 7, 18) firmly connected to the substrate, and

- Through which contact area (16) in the switch-off position (A ') of the second micro-element (2) the two fixed contacts (1, 7.1, 8) are conductively connected to one another.

20. Micro-electromechanical system according to one of claims 1 to 9 or 18 or 19, wherein

(a) the substrate (S) is in the form of a solid with a major surface, characterized in that

(b) that the switching part (5) of the first micro-element (1) is horizontally movable, and

(c) that the movable part (1 1) of the second micro-element (2) is horizontally movable.

21. Process for producing a micro-electromechanical system, in which process

(a) of a substrate (S) a first generated with the substrate connected Mi ^¬ kro element (1), and (b) a second microelement (2) connected to the substrate is produced from a substrate, and

(c) using a structuring method, a first surface (3a) of the first micro-element (1) and a second surface (4a) of the second micro-element (2) are formed, which surfaces (3a, 4a) face each other and from each other are spaced, characterized,

(d) that the first micro-element (1) is shaped such that

- it is in an initial position (A),

- It is bistable from the initial position (A) to a working position (B) and

- The distance of the first surface (3a) from the second surface (4a) in the working position (B) is smaller than a minimum distance that can be generated by the structuring method between the first surface (3a) and the second surface (4a), and

(e) that after the first surface (3a) and the second surface (4a) have been formed by the structuring method, the first micro-element (1) is switched to the working position (B).

22. The manufacturing method according to claim 21, characterized in that before switching the first micro-element (1) into the working position (B), the first surface (3a) of the first micro-element (1) with a first electrically conductive or electrically non-conductive Coating (3b) is provided, and / or the second surface (4a) of the second micro-element (2) is provided with a second electrically conductive or electrically non-conductive coating (4b).

3. Manufacturing method according to one of claims 21 to 22, characterized in that one of the micro-electromechanical systems according to one of claims 1 to 20 is manufactured.