US3584847A

US3584847A - Advancing workpieces through a sputtering chamber

Info

Publication number: US3584847A
Application number: US733553A
Authority: US
Inventors: Charles S Hammond Jr J Tribble; Robert M Tribble; Paul M Johnson Jr
Original assignee: Western Electric Co Inc
Current assignee: AT&T Corp
Priority date: 1968-05-31
Filing date: 1968-05-31
Publication date: 1971-06-15
Anticipated expiration: 1988-06-15

Abstract

An apparatus for depositing a thin film of tantalum to workpieces includes a sputtering chamber and entrance and exit chambers located at opposite ends of and communicating with the sputtering chamber. Sealing devices are provided for isolating the sputtering chamber from the entrance and exit chambers. A reciprocating conveyor having a central conveyor section located within the sputtering chamber, and first and second conveyor sections, located in the entrance and exit chambers, respectively, and which sections may all be connected together, is provided for advancing workpieces from a first magazine in the entrance chamber, through the sputtering chamber, to a second magazine in the exit chamber.

Description

United States Patent [72] Inventors Charles S. Hammond, Jr.; [56] References Cited Joseph C. Tribble; Robert M. Tribble; Paul UNITED STATES PATENTS 21 A I N #2522? 2,583,968 1/1952 Rosseau 263/6 f 3 1968 3,294,670 12/1966 Charschan etal. 214/174 f ml 3,314,873 4/1967 Lunsford 214/17.4

9 [73] Assignee Western Electric Company, Inc. Primary Examiner.l0hn J. Camby New York, N.Y. Artomeysl-l. J. Winegar, R. P. Miller and S. Gundersen ABSTRACT: An apparatus for depositing a thin film of tantalum to workpieces includes a sputtering chamber and entrance and exit chambers located at opposite ends of and communicating with the sputtering chamber. Sealing devices are [54] ES THROUGHA provided for isolating the sputtering chamber from the en- 18 Claims 6 Drawi Fi trance and exit chambers. A reciprocating conveyor having a central conveyor section located within the sputtering [52] U.S.Cl. 263/6, chamber, and first and second conveyor sections, located in 263/36 the entrance and exit chambers, respectively, and which sec- [51 Int. Cl F27b 9/02, tions may all be connected together, is provided for advancing F27b 9/24 workpieces from a first magazine in the entrance chamber, [50] Field of Search 263/6, 36; through the s utterin chamber, to a second ma azine in the P 8 8 2 14/ l 7.4 exit chamber.

I 1. i l 1 1 ea Me e9 Z Z4 56 A M 1'1 1 l 1 a I f0 I 32 PATENTEUJUNISIEIYI I 3,584,847

sum 2 or 4 PATENTED JUN] 5 I97! sum 3 n; 4

PATENTEU JUN 1 5 I97! SHEET W BF 4 ADVANCING WORKPIECES THROUGH A SPUTTERING CHAMBER BACKGROUND OF THE INVENTION I. Field of the Invention In the manufacture of electrical devices, such as tantalum thin film resistors, it is desirable to apply a thin film of tan talum to a workpiece by cathode-sputtering techniques. In order that the sputtering operation be commercially practicable, workpieces to which the thin film of tantalum is applied should be processed continuously through an apparatus capable of performing the sputtering operation. Thus, a sputtering apparatus which is designed to continuously advance workpieces through a sputtering chamber is commercially desirable.

In addition to being designed for continuous processing, the sputtering apparatus should also prevent the ambient atmosphere from affecting the atmosphere inside the sputtering chamber. Thus, a sputtering machine which may be completely isolated from the ambient atmosphere is also commercially desirable. The sputtering machine should be capable of adequately preheating the workpieces before advancement thereof into the sputtering chamber. It is also desirable that the speed of advancement of the workpieces through the apparatus be controllable.

2. Description of the Prior Art In the prior art, various sputtering arrangements have been used to apply a thin film of tantalum to a workpiece. The earliest apparatus used for sputtering included a bell jar into which workpieces to be coated with a tantalum film were inserted. The bell jar apparatus had two primary disadvantages: First, it was not designed for continuous processing of workpieces; and second, the bell jar had to be completely evacuated each time a new batch of workpieces were placed inside.

After development of the bell jar sputtering apparatus, sputtering machines were designed which were capable of continuously processing workpieces through a sputtering chamber. Some machines utilized a sputtering chamber which was, at all times, completely isolated from the ambient atmosphere. Such sputtering machines utilized airlocks located at opposite ends of the machine for feeding workpieces, one at a time, into the sputtering apparatus and for removing workpieces from the sputtering chamber in the same fashion. Other sputtering machines employed a sputtering chamber which was continuously in communication with the ambient atmosphere through restricted openings in opposite ends of the sputtering chamber. In such a machine workpieces could be continuously advanced through the sputtering chamber on a conveyor which extended between the openings in the opposite ends of the chamber. The restricted openings were designed such that the ambient atmosphere had a minimal affect upon the atmosphere maintained in the sputtering chamber.

Another type of sputtering machine, which utilized a sputtering chamber completely isolated from the ambient atmosphere, employed a conveying arrangement in which magazines were fed into the sputtering chamber through airlocks located at entrance and exit sides of the chamber. Once the magazines were located within the sputtering chamber, workpieces were advanced, one at a time, from the magazine at the entrance side of the chamber to the magazine at the exit side of the chamber.

Thus, prior art machines capable of continuously processing workpieces through a sputtering chamber completely isolated from the ambient atmosphere require specially designed airlocks located at opposite ends of the chamber and feeding mechanisms associated with the airlocks for advancing workpieces to and from the exit and entrance locks, respectively. In view of the prior art, a sputtering machine, capable of continuously processing workpieces through a sputtering chamber completely isolated from the ambient atmosphere, utilizing a single conveyor for advancing articles therethrough is desirable. Such an apparatus would eliminate the necessity of providing special handling mechanisms associated with the entrance and exit airlocks to assist a conveyor located within the sputtering chamber to advance workpieces through the apparatus.

SUMMARY OF THE INVENTION The present invention contemplates an apparatus for moving articles through a treating chamber having a controlled atmosphere, such as a sputtering chamber. The apparatus includes a central conveyor section and first and second con veyor sections extending to and from respective entrance and exit openings of the treating chamber. When the conveyor sections are connected together, they may be reciprocated to advance articles into and out of the treating chamber. When the conveyor sections are disconnected, sealing facilities at the respective entrance and exit openings may be operated to seal the treating chamber from the ambient atmosphere.

Additionally, the apparatus includes entrance and exit chambers at the respective entrance and exit openings of the treating chamber. The entrance and exit chambers may themselves be isolated from the ambient atmosphere and provided with respective controlled atmospheres. The first and second conveyor sections are located within the respective entrance and exit chambers. Articles may be subjected to preconditioning and post conditioning in the respective entrance and exit chambers, such as heating and outgassing in the entrance chamber and cooling in the exit chamber, for any desired lengths of time before and after treatment in the treating chamber.

Further, the apparatus is provided with first and second magazines which are mounted within the entrance and exit chambers, respectively. In the operation of the apparatus, the first magazine is loaded with workpieces to be advanced through the sputtering chamber. The second magazine is provided for receiving workpieces which have been advanced through the sputtering chamber. The first conveyor section is designed to remove workpieces from the first magazine and to advance the workpieces to the central section of the conveyor. The second conveyor section receives workpieces advanced along the central conveyor section and inserts the workpieces into the second magazine. When the first magazine is completely exhausted and the second magazine is completely filled, the conveyor sections are disconnected and the sputtering chamber is sealed. Then the entrance and exit chambers are opened to permit the processed workpieces to be removed from the second magazine and unprocessed workpieces to be loaded into the first magazine.

BRIEF DESCRIPTION OF THE DRAWING FIG. 1 is an elevation view, partially in section, of a sputtering apparatus which operates in accordance with the principles of the present invention.

FIG. 2 illustrates schematically first and second magazines located in entrance and exit chambers, respectively, of the sputtering apparatus, and a conveyor along which workpieces are advanced from the first magazine through a sputtering chamber to the second magazine.

FIG. 3 is an enlarged view of a portion of the conveyor shown in FIG. 2.

FIG. 4 is an elevation view, partially in section, of the-entrance chamber and a first section of the conveyor located therein.

FIG. 5 is a sectional view of the first section of the conveyor taken along line 55 of FIG. 4.

FIG. 6 is an elevation view, partially in section, of the exit chamber and a second section of the conveyor located therein.

DETAILED DESCRIPTION In FIG. 1, a sputtering apparatus which incorporates the principles of the present invention is shown. The apparatus ineludes an entrance chamber 19, a sputtering chamber 21, and an exit chamber 23. The sputtering chamber 21 contains a sputtering cathode for applying a metallic coating, such as tantalum, to workpieces advanced through the chamber 21. A first magazine Ml, located in the entrance chamber 19, is provided for receiving unprocessed workpieces to be advanced through the sputtering apparatus. Surrounding the magazine MI is a plurality of heating elements 20-20. The heating elements 20-20 are utilized to raise the temperature of workpieces in the magazine Ml prior to advancement of the workpieces through the apparatus. A second magazine M2 is mounted in the exit chamber 23 for receiving processed workpieces.

An auxiliary heating chamber 24 is located between the entrance chamber 19 and the sputtering chamber 21 and communicates with the entrance chamber 19 through a first sealing device 26. The chamber 24 contains a heating element 22 which is used to maintain workpiece temperature at the level to which the temperature is raised in the entrance chamber 19. Similarly, a chamber 28 is located between the sputtering chamber 21 and the exit chamber 23 and communicates with the exit chamber through a second sealing device 29. The chamber 28 provides for initial cooling of the workpieces after advancement through the sputtering chamber 21. The primary cooling operation is, however, conducted in the exit chamber 23. The

chambers

24 and 28 also serve as buffers for the sputtering chamber 21 to protect the atmosphere in chamber 21 from being contaminated by the atmosphere in the entrance and

exit chambers

19 and 23, respectively.

As shown in FIG. 4, the first sealing device 26 is provided with a slide 26' which may be moved between the entrance chamber 19 and the chamber 24 to seal the

chambers

19 and 24 from each other. In similar fashion, the second sealing device 29 (FIG. 6) is provided with slide 29' which may be moved between the chamber 28 and exit chamber 23 to seal the

chambers

23 and 28 from each other.

CONVEYOR Referring to FIGS. 1 and 2, a conveyor 30 is utilized to advance articles from the entrance chamber 19 through the sputtering chamber 21 to the exit chamber 23. The conveyor 30 comprises three separate portions: (1) a central conveyor section 31 which extends through the sputtering chamber 21 and through the

buffer chambers

24 and 28, respectively; (2) a first conveyor section 32 located within the entrance chamber 19 and extending toward the chamber 24; and (3) a second conveyor section 33 located in the exit chamber 23 and extending toward the chamber 28.

In general, the conveyor 30 includes a pair of stationary parallel guide rails along which workpieces are advanced by a reciprocating advancing mechanism located between the guide rails. As shown in FIGS. 2 and 3, the first section 32 of the conveyor 30 includes a pair of stationary parallel guide rails 42-42. The guide rails 42-42 have longitudinal grooves 42-42a% ,fig. 5) formed on the inner sides thereof for receiving and supporting a workpiece for sliding movement along the guide rails 42-42. Between the guide rails 42-42, a workpiece-advancing mechanism is located. The workpiece-advancing mechanism includes a bar 43 (FIG. 3) mounted for reciprocating movement along a path parallel to the guide rails 42-42. The bar 43 comprises a pair of parallel strips 39-39 which are fastened together by a set of spacers 41-41 located at equal distances along the strips 39-39.

The guide rails 42-42 (FIG. 4) are supported by wall 19 of the entrance chamber 19 and by a yoke 34 mounted within a tubular section 35 of the apparatus located between the chamber 19 and the sealing device 26. As shown in FIG. 5, the yoke 34 includes a pair of

plates

36 and 36 which are fitted together about the guide rails 42-42. Projecting from the sides of the plates 36 and 36' are a set of adjustable arms 37-37 which are used to support the yoke 34 within the tubular section 35. The plate 36 is provided with an opening for receiving the bar 43. At the bottom of the opening, a bead 38 of wear-resistant material, such as hard steel, is provided to support the bar 43 for reciprocating movement. A similar bead 38' (FIG. 4) is mounted on the wall 19 of chamber 19 to support the bar 43. The yoke 34 also supports a pair of roller bearings 40-40 for engaging the sides of bar 43 and guiding the bar 43 in its reciprocating movement. In addition, a pair of guide plates 40'-40' (FIG. 5) are mounted on the yoke 34 above the bar 43 to confine the bar 43 in a desired location in the opening formed in plate 36'.

Referring to FIG. 3, the bar 43 supports a plurality of workpiece-engaging fingers 44-44 which are pivotally mounted within slots 45-45 located between the spacers 41-41. The fingers 44-44 are mounted on pivot pins 44'-44 such that each finger 44, under the effect of gravity, is normally pivoted into a position where one end of the finger 44 rests upon a stop 46 and the other end projects above the bar 43 to engage workpieces to be advanced. When the bar 43 is moved to the left, as viewed in FIG. 3, the fingers 44-44 engage the edges of the workpieces located in the path of movement defined by the guide rails 42-42 to advance the workpieces along the guide rails 42-42.

In order to impart reciprocating movement to the bar 43, a rack 47 and pinion 48 (FIG. 4) are provided. The rack 47 is secured to the bar 43. The pinion 48 engages the rack 47 and is driven by a motor 49 (FIG. 4) to impart movement to the bar 43.

The second section 33 (FIGS. 2 and 6) of conveyor 30 also includes a pair of parallel stationary guide rails 52-52 having longitudinal grooves 52'-52' formed on the inner sides thereof to receive workpieces advanced along the conveyor 30. The guide rails 52-52 are supported by wall 23' of the exit chamber 23 and by a yoke 57 (FIG. 6) which is similar to yoke 34 shown in FIG. 5. A bar 53, which supports a plurality of workpiece engaging fingers 54-54, is mounted for reciprocating movement in a path parallel to the guide rails 52-52. The bar 53 is supported for reciprocating movement by a wear-resistant bead 58' mounted on wall 23' of chamber 23 and by a similar bead (not shown) mounted on the yoke 57. The fingers 54-54 are pivotally mounted to the bar 53 within slots 55-55 formed in the bar 54 at equal distances therealong. The fingers 54-54 are arranged to be normally pivoted upward into positions to engage workpieces supported by the guide rails 52-52.

The central section 31 (FIG. 2) of the conveyor 30 includes a pair of parallel guide rails 62-62 having longitudinal grooves 62-62a% ,figs. 4 and 6) formed on the inner sides thereof for receiving and supporting workpieces. As indicated in FIG. 2, the guide rails 62-62 are divided into a series of rail sections to allow for longitudinal expansion thereof resulting from the heat generated during the operation of the apparatus. Referring to FIG. 1, the guide rail sections are supported by the chamber walls through which the rail sections are inserted and by flexible supports located in the center of each of the

chambers

21, 24, and 28. A pair of yokes 67 and 68 (FIGS. 4 and 6, respectively) are also provided for supporting the guide rails 62-62.

A bar 63 is mounted between the guide rails 62-62 for reciprocating movement in the path parallel to the guide rails 62-62. The bar 63 is supported for reciprocating movement by wear-resistant beads formed on the yokes 67 and 68 and by similar beads located in the walls of

chambers

21, 24, and 28. The bar 63 also supports a plurality of workpiece-engaging fingers 64-64 which are pivotally mounted within slots 65-65 formed at equal distances along the bar 63. The fingers 64-64 are mounted on the bar 63 in such fashion that, under the action of gravity, the fingers 64-64 are normally pivoted upward into workpiece engaging positions.

Referring to FIG. 4, the guide rails 42-42 are aligned with and spaced from the center guide rails 62-62 to permit the slide 26 of the sealing device 26 to move therebetween to seal the entrance chamber 19 from the heating chamber 24. Similarly, as shown in FIG. 6, the guide rails 52-52 are aligned with and spaced from the center guide rails 62-62 to permit the slide 29' of the sealing device 29 to move therebetween and seal the exit chamber 23 from the cooling chamber 28.

As shown in FIGS. 1 and 2, the chamber 24 is provided with a pair of devices 50-50 for establishing restricted openings through which workpieces are advanced during movement along conveyor 30. The devices 50-50 are mounted over the guide rails of conveyor 30 and located at opposite sides of the chamber 24. The purpose of the devices 50-50 is to isolate, as effectively as possible, the

chambers

19 and 24 from the sputtering chamber 21. Similarly, the chamber 28 is also provided with a pair of devices 50-50' for isolating the sputtering chamber 21 from the

chambers

23 and 28.

WORKPIECE-ADVANCING MECHANISM The reciprocating mechanism for advancing workpieces along the guide rails 42-42, 52-52, and 62-62 of the conveyor 30, consists of three separate portions; i.e., the reciprocating bars 43, 53, and 63 and the associated workpiece-engaging fingers 44-44, 54-54, and 64-64, described above. Referring to FIG. 4, the bar 63 is provided at the end thereof adjacent to the sealing device 26 with a latch 71 pivotally mounted thereon. The latch 71 has a notch 71' formed therein for engaging a projection 72 extending from the bar 43. A stationary air cylinder 73, located outside the sealing device 26, is provided for operating the latch 71. A piston rod 74 extending from the air cylinder 73 through a tubular section 75 of the sputtering apparatus supports a member 76 having a projection 76"for engaging an arm 77 extending from the latch 71. When the air cylinder 73 is operated to move the piston rod 74 downward, the projection 76' moves into engagement with the arm 77 to pivot the latch 71.

In the operation of the apparatus, when the pinion 48 is rotated to move the bar 43 leftward, as viewed in FIG. 4, the projection 72 on the bar 43 moves to a position where it is engaged by the latch 71 to couple the bars 43 and 63 together. Thereafter, reciprocating movement may be imparted to the coupled bars 43 and 63 through the rack 47 and pinion 48. The bars 43 and 63 may be uncoupled by returning the bar 63 to its initial position (FIG. 4) and operating the air cylinder 73 to pivot the latch 71 which disengages the projection 72. The bar 43 may be returned to its initial position without moving the bar 63.

A similar coupling arrangement (FIG. 6) is provided for connecting the bar 53 to the other end of the bar 63. A latch 81, pivotally mounted on the bar 53, has a notch 81' formed therein for engaging a projection 82 formed on the bar 63. A stationary air cylinder 83, having a piston rod 84 extending through an outer wall of the sputtering apparatus, is provided for operating the latch 81. A member 86 is mounted on the piston rod 84 and is provided with a projection 86' for engaging an arm 87 extending from the latch 81. The coupling and uncoupling of the bars 53 and 63 byoperation of the latch 81 to engage and disengage the projection 82 is similar to the operation of the latch 71 and projection 72 described above.

Thus, both bars 43 and 53 may be connected to the bar 63 by operation of the latches 71 and 81. Workpieces may be then advanced along the path defined by guide rails 42-42, 52-52, and 62-62 by imparting reciprocating movement to the coupled bars 43, 53 and 63 through the rack 47 and pinion 48 mechanism. When the advancing mechanism, i.e., the coupled bars 43, 53 and 63, is moved to the left, as viewed in FIGS. 4 and 6, the workpiece-engaging fingers 44-44, 54-54 and 64-64 engage the edges of workpieces supported by the guide rails 42-42, 52-52, and 62-62, and advance the workpieces to the left. When the leftward stroke of the advancing mechanism is completed, the motion of the coupled bars 43, 53 and 63 is reversed.

Upon movement of the advancing mechanism to the right, the workpiece-engaging fingers 44-44, 54-54 and 64-64 pivot into horizontal positions to bypass the advanced workpieces. Thus, the workpieces remain in their advanced positions while the advancing mechanism is moved to the right, as viewed in FIGS. 4 and 6. When the rightward stroke of the advancing mechanism is completed, the fingers 44-44, 54-54, and 64-64 are moved into positions located between the workpieces. The fingers 44-44, 54-54 and 64-64 are then able to pivot into the spaces between adjacent workpieces by virtue of gravitational forces exerted thereon. Then leftward movement may be imparted to the advancing mechanism to repeat the advancing sequence. In this manner, workpieces are conveyed in step-bystep fashion along the conveyor 30.

ENTRANCE AND EXIT MAGAZINES Referring to FIG. 2, the magazine M1 for receiving unprocessed workpieces includes a plurality of vertical support members 20'-20' having grooves or notches (FIG. 4) formed on the inner sides thereof for receiving and supporting unprocessed workpieces. The workpieces may be in the form of rectangular plates to which a thin film of tantalum is to be applied. Alternatively, the support members 20'-20' of the magazine M1 may be utilized to receive a plurality of rectangular pallets upon which small workpieces, such as ceramic bodies, may be supported during advancement through the sputtering apparatus.

An elevating mechanism is provided for raising and lowering the magazine M1 relative to the first section 32 of the conveyor 30. As shown in FIGS. 2 and 4, the elevating mechanism may comprise a screw which is threaded into an opening formed in the bottom of the magazine M1. A motor (not illustrated) may be provided to turn the screw thereby raising or lowering the magazine M1.

In preparing the apparatus for a sputtering operation, the magazine M1 is initially located in a raised position relative to the conveyor section 32. With the sealing device 26 operated to seal the chamber 24, the entrance chamber 19 may be opened in order to allow the magazine M1 to be loaded with unprocessed workpieces. During the sputtering operation of the apparatus, the elevating mechanism is operated to lower the magazine M1 to feed the workpieces, one at a time, to the conveyor section 32.

At the opposite end of the sputtering machine, a second magazine M2 is located within the exit chamber 23. The magazine M2 also includes a plurality of vertical support members 18-18 having grooves or notches (FIG. 6) for receiving and supporting workpieces which have been advanced through the sputtering apparatus. An elevating mechanism, similar to that shown in FIG. 4, is provided for raising and lowering the magazine M2 relative to the conveyor section 33. Prior to the initiation of the sputtering operation, the magazine M2, as indicated in FIG. 2, is located in a lowered position relative to the conveyor section 32. During the advancement of workpieces through the sputtering apparatus, the magazine M2 is raised relative to the conveyor section 32 to receive processed workpieces, one at a time, from the sputtering section of the apparatus. When the sputtering operation is completed, the magazine M2 is located in a raised position relativeto the conveyor section 32 and is completely filled with workpieces. In order to facilitate the unloading of the magazine M2, the sealing device 29 is operated to seal the exit chamber 23 from the cooling chamber 28. Then the exit chamber 23 may be opened to allow the processed workpieces to be unloaded from the magazine M2.

OPERATION In the operation of the sputtering apparatus of the present invention, the sputtering chamber 21 is maintained at a high level of evacuation. The

buffer chambers

24 and 28 are maintained at levels of evacuation which are higher than the evacuation level of the sputtering chamber 21, i.e., the pressures in the

chambers

24 and 28 is less than the pressure in the chamber 21. A predetermined mixture of nitrogen and argon is supplied to the sputtering chamber 21.

Since it is desirable to maintain the atmosphere in the sputtering chamber 21 at a constant level of evacuation and to prevent contamination of the nitrogen and argon mixture, it is necessary to isolate the

chambers

21, 24 and 28 from the ambient atmosphere at all times. For this reason, the sealing

devices

26 and 29 are provided to prevent the ambient atmosphere from entering the

chambers

21, 24 and 28 when the entrance chamber 19 and the exit chamber 23 are exposed to the ambient atmosphere.

Prior to initiation of a sputtering operation, the slides 26 and 29' of the

sealing devices

26 and 29, respectively, are closed to isolate the sputtering chamber 21 from the entrance chamber 19 and the exit chamber 23. At this time, the entrance chamber 19 may be opened to allow workpieces to be loaded into the magazine M1. The exit chamber 23 may also be opened to allow processed workpieces to be removed from the magazine M2.

At the beginning of a sputtering operation, the magazine M1 is located in a raised position (FIG. 4) relative to the conveyor section 32 and is completely filled with workpieces. The magazine M2 is located in a lowered position relative to the conveyor section 33 (FIG. 6).

The entrance chamber 19 and the exit chamber 23 are closed and then evacuated until the level of pressure therein is equal to the pressures maintained in the

chambers

24 and 28. The temperature of the workpieces is raised to a desired level by the heating elements -20. The slides 26' and 29' of the

sealing devices

26 and 29, respectively, are then opened. The entrance chamber 19 is thus in communication with the chamber 24 and the exit chamber 23 is in communication with the chamber 28.

At this point, the bar 43 is advanced to the left, as viewed in FIG. 4, by rotating the pinion 48 in a counterclockwise direction. When the bar 43 moves a sufiicient distance to the left, the projection 72 formed on the bar 43 moves into the notch 71 formed in the latch 71 on the bar 63. The bars 43 and 63 are thus connected by the latch 71. Upon continued rotation of the pinion 48 to move the bar 43 to the left, the bar 63 which is coupled to the bar 43 also moves in this direction. When the bar 63 is moved a sufficient distance, the projection 82 formed on the bar 63 moves into the notch 81' formed in the latch 81 on the bar 53 (FIG. 6). The bar 63 is thus connected to the bar 53 by the latch 81.

Since the bars 43, 53 and 63 are connected together, reciprocating motion imparted to the bar 43 through the rack 47 and pinion 48 is also transmitted to the bars 53 and 63. It is by virtue of this reciprocating movement that workpieces are advanced from the magazine M1 through the sputtering apparatus to the magazine M2. During a leftward stroke of the workpiece advancing mechanism, the fingers 44-44, 54-54, and 64-64 engage and advance workpieces along the guide rails 42-42, 52-52 and 62-62 of the conveyor 30. The fingers 44-44 mounted on the bar 43 advance workpieces from the magazine M1 along the guide rails 42-42. After the workpieces are advanced through the sealing device 26, the workpieces are received by the guide rails 62-62 and are further advanced by the fingers 64-64 mounted on the reciprocating bar 63.

The workpieces are then advanced through the chamber 24 beneath the heating element 22 which maintains the workpieces of the desired temperature. Continued reciprocation of the bar 63 and the fingers 64-64 advances the workpieces through the sputtering chamber 21 past a sputtering cathode which applies a thin film of tantalum to the workpieces. Next, the coated workpieces are advanced through the chamber 28, beneath a cooling panel 28, where initial cooling of the workpieces takes place. Upon advancement through the second sealing device 29, the workpieces are moved to the guide rails 52-52. The workpieces are then advanced along the guide rails 52-52 by the operation of the reciprocating bar 53 and the fingers 54-54 mounted thereon. The bar 53 and fingers 54-54 advance the workpieces to the magazine M2.

During the reciprocation of the workpiece-advancing mechanism, the magazine M1 is lowered by the elevating mechanism located in the entrance chamber 19 to present workpieces, supported by the magazine M1, one at a time, to the conveyor section 32. At the same time, the magazine M2 is raised by the elevating mechanism located in the exit chamber 23, by one step at a time, to permit workpieces advanced along the conveyor section 33 to be received in the magazine M2.

The reciprocation of the workpiece-advancing mechanism is continued until all the workpieces originally located in the magazine M1 are advanced through the sputtering apparatus and received in the magazine M2. After the magazine M2 is completely filled with workpieces, the bar 53 is returned to its initial position, as shown in FIG. 6, and the air cylinder 83 is operated to pivot the latch 81 to disconnect the bar 53 from the bar 63.

Then the bar 63 is returned to its initial position, as shown in FIG. 4, to locate the arm 77 of the latch 71 adjacent to the member 76 supported by the piston rod 74. At this point, the air cylinder 73 is operated to pivot the latch 71 to disconnect the bar 43 from the bar 63. Then the bar 43 is returned to its initial position without affecting the position of the bar 63.

After the bars 43, 53 and 63 are disconnected and located in their original positions, the slides 26 and 29' of the first and

second sealing devices

26 and 29, respectively, are closed to seal the entrance chamber 19 from the chamber 24 and to seal the exit chamber 23 from the chamber 28. The processed workpieces are then allowed to cool in the exit chamber 23.

After the

sealing devices

26 and 29 are closed and the workpieces are cooled, the pressure in the exit chamber is raised to atmospheric level and the exit chamber 23 is opened to permit the processed workpieces to be unloaded from the magazine M2. It should be noted that the magazine M2, at this time, is located in a raised position relative to the conveyor section 33.

When the processed workpieces have been unloaded from the magazine M2, the sputtering apparatus may then be prepared for a subsequent sputtering operation. The magazine M2 is moved to its original lowered position relative to the conveyor section 33. The exit chamber 23 is closed. The entrance chamber 19 is opened and the magazine M1 is moved to its initial raised position relative to the conveyor section 32.

Then as described above, the magazine Ml, may be loaded with unprocessed workpieces to be advanced through the sputtering apparatus. The entrance chamber 19 is then closed and the sputtering operation described above may be repeated to advance the workpieces from the magazine Ml through the sputtering apparatus to the magazine M2.

In order to regulate the amount of tantalum deposited on the workpieces in the sputtering chamber 21, the speed of reciprocation of the workpiece-advancing mechanism is made variable by providing a control device (not shown) for varying the speed of motor 49 (FIG. 4). By adjusting the speed ofthe motor 49 to a desired value, the thickness of the thin film coating of tantalum applied to the workpieces may be controlled.

In the operation of the sputtering apparatus, it may be desirable to further limit communication between the sputtering chamber 21 and

buffer chambers

24 and 28 by positioning workpieces within the

devices

50 and 50 located adjacent to chamber 21 for the time during which the

chambers

19 and 23 are exposed to the ambient atmosphere. This result may be accomplished by removing two of the fingers 64-64 from the bar 63, a first finger 64 which reciprocates through the device 50 located at the exit side of chamber 24 and a second finger 64 which reciprocates through the device 50 located at the entrance side of chamber 28. With these two fingers 64-64 removed, the conveyor 30, in advancing the final two workpieces from the magazine Ml, will operate to advance the first of the workpieces into the device 50 and the last of the workpieces into the device 50. The workpieces will then remain in these positions until another group of workpieces is loaded into the magazine M1 and advanced through the apparatus. It

should be noted that the final two workpieces in the magazine M1 will only be advanced as far as the

devices

50 and 50 located adjacent to the sputtering chamber 21.

It should be noted that the above-described apparatus is merely illustrative of the principles of the present invention. The conveying system described herein is not limited to utilization with an apparatus capable of performing only sputtering operations. The system may be incorporated in any apparatus where it is desirable to advance workpieces through a treating chamber which is isolated from the ambient atmosphere. In addition, the structure of the apparatus and its mode of operation may be modified by persons having ordinary skill in the art without departing from the scope of this invention.

What we claim is:

1. An apparatus for moving articles through a treating chamber having a controlled atmosphere maintained therein, which comprises:

a reciprocating conveyor for advancing articles through the treating chamber, said conveyor including (l) a central conveyor section mounted for reciprocating movement in the treating chamber and (2) first and second conveyor sections, mounted for reciprocating movement at opposite ends of the treating chamber, detachably connected to said central conveyor section; and

means for sealing the treating chamber from the outside atmosphere when said conveyor sections are disconnected.

2. An apparatus for moving articles through a treating chamber having entrance and exit openings formed in opposite sides thereof and having a controlled atmosphere maintained therein, which comprises:

a reciprocating conveyor for advancing articles through the treating chamber, said conveyor including (1) a central conveyor section extending through the treating chamber and mounted for reciprocating movement along a path extending between the entrance and exit openings formed -in the chamber, (2) first and second conveyor sections located outside the treating chamber at opposite ends of and aligned with said central conveyor section and mounted for reciprocating movement along paths parallel to the path of reciprocation of said central conveyor section;

means selectively operable for coupling said first and second conveyor sections together;

means for imparting reciprocating movement to the coupled conveyor sections to advance articles through the treating chamber during forward movement of the con-' veyor sections; and means for sealing the entrance and .exit openings of the treating chamber to seal the interior of the chamber from the ambient atmosphere when said conveyor sections are uncoupled.

3. An apparatus for moving articles through a treating chamber having entrance and exit openings formed in opposite sides thereof and having a controlled atmosphere maintained therein, as set forth in claim 2, which includes:

means on said conveyor sections for engaging articles to be advanced during the forward movement of the conveyor sections and for disengaging the articles during backward movement of said conveyor sections.

4. An apparatus for moving articles through a treating chamber having entrance and exit openings formed in opposite sides thereof and having a controlled atmosphere maintained therein, as set forth in claim 3, wherein:

said article-engaging means comprises a plurality of gravityoperated fingers, pivotally mounted to the conveyor sections at equal distances along said conveyor sections, said fingers being normally urged into article-engaging positions by gravity during forward movement of the conveyor sections and being pivoted to bypass the articles during backward movement of said conveyor sections.

5. In an apparatus for moving articles through a treating chamber having entrance and exit openings formed in opposite sides thereof and having a controlled atmosphere maintained therein:

entrance and exit chambers located at opposite ends of and communicating with the treating chamber through the entrance and exit openings, respectively; a conveyor for advancing articles from said entrance 5 chamber, through said treating chamber to said exit chamber, said conveyor including 1) a central conveyor section mounted in said treating chamber for reciprocating movement in a path extending from the entrance opening to the exit opening, and (2) first and second conveyor sections, mounted in said entrance and exit chambers, respectively, for reciprocating movement in paths parallel to the path of reciprocation of said central conveyor section; means selectively operable for connecting said first and second conveyor sections to said central conveyor section; means for imparting reciprocating movement to the connected conveyor sections to advance articles through said treating chamber during forward movement of said conveyor sections; and

means operable when said conveyor sections are disconnected for sealing said entrance and exit chambers from said treating chamber. 6. In an apparatus for conveying articles through a treating 4 chamber having a controlled atmosphere maintained therein:

entrance and exit chambers located at opposite ends of and communicating with the treating chamber;

a conveyor track having a center track section extending through the treating chamber for receiving and guiding articles in movement through that chamber, a first track section extending from said entrance chamber toward said center track section and a second track section extending from said exit chamber toward said center track 3 section;

first means located between said entrance chamber and the treating chamber and mounted to move between said first and center track sections for sealing the treating chamber from said entrance chamber;

second means located between said exit chamber and the treating chamber mounted to move between said center and second track sections for sealing the treating chamber from said exit chamber; and

article-engaging means mounted for reciprocating movement along said track sections to move articles from said entrance chamber through the treating chamber to said exit chamber, said engaging means including a central portion for engaging articles on said center track section and first and second portions separable from said central portion for engaging articles on said first and second track sections, respectively.

7. An apparatus for advancing workpieces through a sputtering chamber having entrance and exit openings formed in opposite sides thereof and having a controlled atmosphere maintained therein, which comprises:

entrance and exit chambers located at opposite ends of and communicating with the sputtering chamber through the entrance and exit openings, respectively;

central guide means extending through the sputtering chamber for receiving and guiding workpieces in movement through that chamber;

first and second guide means located in said entrance and exit chambers, respectively, and aligned with said central guide means in the sputtering chamber;

workpiece-advancing means mounted for reciprocating movement along said guide means to engage and move workpieces along said guide means to engage and move workpieces along said first guide means in said entrance chamber to said central guide means in the sputtering chamber and then to said second guide means in said exit chamber, said advancing means including a central port on for engaging workpieces on said central guide means and first and second portions, which may be coupled to said central portion for engaging workpieces on said first and second guide means, respectively;

means for imparting reciprocating movement to said workpiece-advancing means after the portions thereof are coupled together to advance workpieces along said guide means during forward movement of said workpiece-advancing means in a direction extending from said entrance chamber toward said exit chamber;

a first sealing device located between said entrance chamber and the sputtering chamber for sealing the sputtering chamber from said entrance chamber when said first and central portions of said workpiece-engaging means are uncoupled; and

a second sealing device located between said exit chamber and the sputtering chamber for sealing the sputtering chamber from said exit chamber when the central and second portions of said workpiece-engaging means are uncoupled.

8. An apparatus for advancing workpieces through a sputtering chamber having entrance and exit openings formed in opposite sides thereof and having a controlled atmosphere maintained therein, as set forth in claim 7, which includes:

a plurality of fingers, pivotally mounted on the portions of said workpiece-advancing means at equal distances therealong, for engaging workpieces on said guide means during forward movement of said workpiece-advancing means and for disengaging the workpieces during backward movement of said workpiece-advancing means.

9. An apparatus for advancing workpieces through a sputtering chamber having entrance and exit openings formed in opposite sides thereof and having a controlled atmosphere maintained therein, as set forth in claim 8, wherein:

said fingers are normally urged into workpiece-engaging positions by gravity during forward movement of said workpiece-advancing means and are pivoted to bypass the advanced workpieces during backward movement of said workpiece-advancing means.

10. An apparatus for advancing workpieces through a sputtering chamber having entrance and exit openings formed in opposite sides thereof and having a controlled atmosphere maintained therein, as set forth in claim 7, which includes:

heating means mounted in said entrance chamber for raising the temperature of workpieces located in said entrance chamber to a desired level prior to advancement of the workpieces into the sputtering chamber.

11. An apparatus for advancing workpieces through a sputtering chamber having entrance and exit openings formed in opposite sides thereof and having a controlled atmosphere maintained therein, as set forth in claim 7, which includes:

a first magazine located within said entrance chamber for receiving a plurality of workpieces to be advanced through the sputtering chamber, said first magazine being mounted to move relative to the first portion of said workpiece-advancing mechanism to feed the workpieces, one at a time, to said first portion of said workpiece-advancing mechanism;

a second magazine located with said exit chamber for receiving workpieces after advancement thereof through the sputtering chamber, said second magazine being mounted to move relative to the second portion of said workpiece advancing mechanism to remove workpieces, one at a time, from said second portion of said workpieceadvancing mechanism; and

means for moving said first and second magazines relative to said first and second portions of said workpiece-advancing mechanism, respectively, to feed workpieces to said workpiece-advancing mechanism in said entrance chamber and to remove workpieces from said advancing mechanism in said exit chamber.

12. An apparatus for moving articles into a treating chamber having an entrance opening formed therein and having a controlled atmosphere maintained therein, which comprises:

a conveyor for advancing articles through the entrance opening into the treating chamber, said conveyor inc|uding 1) an internal conveyor section located inside the treating chamber with one end thereof adjacent to the entrance opening, said internal section being mounted for reciprocating movement and (2) an external conveyor section located outside the treating chamber with one end thereof adjacent to the entrance opening, said external conveyor section also mounted for reciprocating movement;

means selectively operable for connecting said external conveyor section to said internal conveyor section;

means for imparting reciprocating movement to the connected conveyor sections to advance articles from said external conveyor section to said internal conveyor section; and

means for sealing the treating chamber from the ambient atmosphere when said internal and external conveyor sections are disconnected.

13. In an apparatus for moving articles into a treating chamber having an entrance opening formed therein and having a controlled atmosphere maintained therein:

an entrance chamber located at one end of and communicating with the treating chamber through the entrance opening;

a conveyor for advancing articles from said entrance chamber through the entrance opening into said treating chamber, said conveyor including (1) an internal conveyor section located inside the treating chamber with one end thereof adjacent to the entrance opening, said internal conveyor section mounted for reciprocating movement along a path extending from the entrance opening into the treating chamber, and (2) an external conveyor section located in the entrance chamber with one end thereof adjacent to the entrance opening, said external conveyor section being mounted for reciprocating movement along a path parallel to the path of reciprocation of said internal conveyor section;

means selectively operable for coupling said external conveyor section to said internal conveyor section;

means for imparting reciprocating movement to the coupled conveyor sections to advance articles from said entrance chamber into the treating chamber; and

means for sealing said treating chamber from said entrance chamber when said internal and external conveyor sections are disconnected.

14. An apparatus for conveying articles, which comprises:

a central conveyor section mounted for reciprocating movement along a path through which articles are to be conveyed;

first and second conveyor sections located adjacent to opposite ends of the central conveyor section and mounted for reciprocating movement along said path;

means selectively operable for connecting said first and second conveyor sections to said central conveyor section; and

means for imparting reciprocating movement to the connected conveyor sections to advance articles, during forward movement of the conveyor sections, from said first conveyor section along said central conveyor section to said second conveyor section.

15. An apparatus for conveying articles, as set forth in claim 14, which includes:

means on said conveyor sections for engaging articles to be advanced during forward movement of said conveyor sections and for disengaging the advanced articles during backward movement of said conveyor sections.

16. An apparatus for conveying articles, as set forth in claim 15, wherein:

said article-engagin g means comprises a plurality of gravityoperated fingers located at equal distances along said conveyor sections which are urged into article engaging positions by gravity during forward movement of the conveyor sections and pivot to bypass the advanced articles during backward movement ofsaid conveyor sections.

17. In an apparatus for conveying articles:

a first conveyor section mounted for reciprocating movement along a path in which articles are to be conveyed;

a second conveyor section mounted for reciprocating movement along said path and located adjacent to said first conveyor section;

connecting means operated upon movement of said first conveyor section into engagement with said second conveyor section for connecting said first and second conveyor sections; and

means for imparting reciprocating movement to said first

Claims

1. An apparatus for moving articles through a treating chamber having a controlled atmosphere maintained therein, which comprises: a reciprocating conveyor for advancing articles through the treating chamber, said conveyor including (1) a central conveyor section mounted for reciprocating movement in the treating chamber and (2) first and second conveyor sections, mounted for reciprocating movement at opposite ends of the treating chamber, detachably connected to said central conveyor section; and means for sealing the treating chamber from the outside atmosphere when said conveyor sections are disconnected.

2. An apparatus for moving articles through a treating chamber having entrance and exit openings formed in opposite sides thereof and having a controlled atmosphere maintained therein, which comprises: a reciprocating conveyor for advancing articles through the treating chamber, said conveyor incluDing (1) a central conveyor section extending through the treating chamber and mounted for reciprocating movement along a path extending between the entrance and exit openings formed in the chamber, (2) first and second conveyor sections located outside the treating chamber at opposite ends of and aligned with said central conveyor section and mounted for reciprocating movement along paths parallel to the path of reciprocation of said central conveyor section; means selectively operable for coupling said first and second conveyor sections together; means for imparting reciprocating movement to the coupled conveyor sections to advance articles through the treating chamber during forward movement of the conveyor sections; and means for sealing the entrance and exit openings of the treating chamber to seal the interior of the chamber from the ambient atmosphere when said conveyor sections are uncoupled.

3. An apparatus for moving articles through a treating chamber having entrance and exit openings formed in opposite sides thereof and having a controlled atmosphere maintained therein, as set forth in claim 2, which includes: means on said conveyor sections for engaging articles to be advanced during the forward movement of the conveyor sections and for disengaging the articles during backward movement of said conveyor sections.

4. An apparatus for moving articles through a treating chamber having entrance and exit openings formed in opposite sides thereof and having a controlled atmosphere maintained therein, as set forth in claim 3, wherein: said article-engaging means comprises a plurality of gravity-operated fingers, pivotally mounted to the conveyor sections at equal distances along said conveyor sections, said fingers being normally urged into article-engaging positions by gravity during forward movement of the conveyor sections and being pivoted to bypass the articles during backward movement of said conveyor sections.

5. In an apparatus for moving articles through a treating chamber having entrance and exit openings formed in opposite sides thereof and having a controlled atmosphere maintained therein: entrance and exit chambers located at opposite ends of and communicating with the treating chamber through the entrance and exit openings, respectively; a conveyor for advancing articles from said entrance chamber, through said treating chamber to said exit chamber, said conveyor including (1) a central conveyor section mounted in said treating chamber for reciprocating movement in a path extending from the entrance opening to the exit opening, and (2) first and second conveyor sections, mounted in said entrance and exit chambers, respectively, for reciprocating movement in paths parallel to the path of reciprocation of said central conveyor section; means selectively operable for connecting said first and second conveyor sections to said central conveyor section; means for imparting reciprocating movement to the connected conveyor sections to advance articles through said treating chamber during forward movement of said conveyor sections; and means operable when said conveyor sections are disconnected for sealing said entrance and exit chambers from said treating chamber.

6. In an apparatus for conveying articles through a treating chamber having a controlled atmosphere maintained therein: entrance and exit chambers located at opposite ends of and communicating with the treating chamber; a conveyor track having a center track section extending through the treating chamber for receiving and guiding articles in movement through that chamber, a first track section extending from said entrance chamber toward said center track section and a second track section extending from said exit chamber toward said center track section; first means located between said entrance chamber and the treating chamber and mounted to move between said first and center track sections for sealing tHe treating chamber from said entrance chamber; second means located between said exit chamber and the treating chamber mounted to move between said center and second track sections for sealing the treating chamber from said exit chamber; and article-engaging means mounted for reciprocating movement along said track sections to move articles from said entrance chamber through the treating chamber to said exit chamber, said engaging means including a central portion for engaging articles on said center track section and first and second portions separable from said central portion for engaging articles on said first and second track sections, respectively.

7. An apparatus for advancing workpieces through a sputtering chamber having entrance and exit openings formed in opposite sides thereof and having a controlled atmosphere maintained therein, which comprises: entrance and exit chambers located at opposite ends of and communicating with the sputtering chamber through the entrance and exit openings, respectively; central guide means extending through the sputtering chamber for receiving and guiding workpieces in movement through that chamber; first and second guide means located in said entrance and exit chambers, respectively, and aligned with said central guide means in the sputtering chamber; workpiece-advancing means mounted for reciprocating movement along said guide means to engage and move workpieces along said guide means to engage and move workpieces along said first guide means in said entrance chamber to said central guide means in the sputtering chamber and then to said second guide means in said exit chamber, said advancing means including a central portion for engaging workpieces on said central guide means and first and second portions, which may be coupled to said central portion for engaging workpieces on said first and second guide means, respectively; means for imparting reciprocating movement to said workpiece-advancing means after the portions thereof are coupled together to advance workpieces along said guide means during forward movement of said workpiece-advancing means in a direction extending from said entrance chamber toward said exit chamber; a first sealing device located between said entrance chamber and the sputtering chamber for sealing the sputtering chamber from said entrance chamber when said first and central portions of said workpiece-engaging means are uncoupled; and a second sealing device located between said exit chamber and the sputtering chamber for sealing the sputtering chamber from said exit chamber when the central and second portions of said workpiece-engaging means are uncoupled.

8. An apparatus for advancing workpieces through a sputtering chamber having entrance and exit openings formed in opposite sides thereof and having a controlled atmosphere maintained therein, as set forth in claim 7, which includes: a plurality of fingers, pivotally mounted on the portions of said workpiece-advancing means at equal distances therealong, for engaging workpieces on said guide means during forward movement of said workpiece-advancing means and for disengaging the workpieces during backward movement of said workpiece-advancing means.

9. An apparatus for advancing workpieces through a sputtering chamber having entrance and exit openings formed in opposite sides thereof and having a controlled atmosphere maintained therein, as set forth in claim 8, wherein: said fingers are normally urged into workpiece-engaging positions by gravity during forward movement of said workpiece-advancing means and are pivoted to bypass the advanced workpieces during backward movement of said workpiece-advancing means.

10. An apparatus for advancing workpieces through a sputtering chamber having entrance and exit openings formed in opposite sides thereof and having a controlled atmosphere maintained therein, as set forth in claim 7, which includes: heating means mounted in said entrancE chamber for raising the temperature of workpieces located in said entrance chamber to a desired level prior to advancement of the workpieces into the sputtering chamber.

11. An apparatus for advancing workpieces through a sputtering chamber having entrance and exit openings formed in opposite sides thereof and having a controlled atmosphere maintained therein, as set forth in claim 7, which includes: a first magazine located within said entrance chamber for receiving a plurality of workpieces to be advanced through the sputtering chamber, said first magazine being mounted to move relative to the first portion of said workpiece-advancing mechanism to feed the workpieces, one at a time, to said first portion of said workpiece-advancing mechanism; a second magazine located with said exit chamber for receiving workpieces after advancement thereof through the sputtering chamber, said second magazine being mounted to move relative to the second portion of said workpiece advancing mechanism to remove workpieces, one at a time, from said second portion of said workpiece-advancing mechanism; and means for moving said first and second magazines relative to said first and second portions of said workpiece-advancing mechanism, respectively, to feed workpieces to said workpiece-advancing mechanism in said entrance chamber and to remove workpieces from said advancing mechanism in said exit chamber.

12. An apparatus for moving articles into a treating chamber having an entrance opening formed therein and having a controlled atmosphere maintained therein, which comprises: a conveyor for advancing articles through the entrance opening into the treating chamber, said conveyor including (1) an internal conveyor section located inside the treating chamber with one end thereof adjacent to the entrance opening, said internal section being mounted for reciprocating movement and (2) an external conveyor section located outside the treating chamber with one end thereof adjacent to the entrance opening, said external conveyor section also mounted for reciprocating movement; means selectively operable for connecting said external conveyor section to said internal conveyor section; means for imparting reciprocating movement to the connected conveyor sections to advance articles from said external conveyor section to said internal conveyor section; and means for sealing the treating chamber from the ambient atmosphere when said internal and external conveyor sections are disconnected.

13. In an apparatus for moving articles into a treating chamber having an entrance opening formed therein and having a controlled atmosphere maintained therein: an entrance chamber located at one end of and communicating with the treating chamber through the entrance opening; a conveyor for advancing articles from said entrance chamber through the entrance opening into said treating chamber, said conveyor including (1) an internal conveyor section located inside the treating chamber with one end thereof adjacent to the entrance opening, said internal conveyor section mounted for reciprocating movement along a path extending from the entrance opening into the treating chamber, and (2) an external conveyor section located in the entrance chamber with one end thereof adjacent to the entrance opening, said external conveyor section being mounted for reciprocating movement along a path parallel to the path of reciprocation of said internal conveyor section; means selectively operable for coupling said external conveyor section to said internal conveyor section; means for imparting reciprocating movement to the coupled conveyor sections to advance articles from said entrance chamber into the treating chamber; and means for sealing said treating chamber from said entrance chamber when said internal and external conveyor sections are disconnected.

14. An apparatus for conveying articles, which comprises: a central conveyor section mounted for reciprocating movement along a path through which articles are to be conveyed; first and second conveyor sections located adjacent to opposite ends of the central conveyor section and mounted for reciprocating movement along said path; means selectively operable for connecting said first and second conveyor sections to said central conveyor section; and means for imparting reciprocating movement to the connected conveyor sections to advance articles, during forward movement of the conveyor sections, from said first conveyor section along said central conveyor section to said second conveyor section.

15. An apparatus for conveying articles, as set forth in claim 14, which includes: means on said conveyor sections for engaging articles to be advanced during forward movement of said conveyor sections and for disengaging the advanced articles during backward movement of said conveyor sections.

16. An apparatus for conveying articles, as set forth in claim 15, wherein: said article-engaging means comprises a plurality of gravity-operated fingers located at equal distances along said conveyor sections which are urged into article engaging positions by gravity during forward movement of the conveyor sections and pivot to bypass the advanced articles during backward movement of said conveyor sections.

17. In an apparatus for conveying articles: a first conveyor section mounted for reciprocating movement along a path in which articles are to be conveyed; a second conveyor section mounted for reciprocating movement along said path and located adjacent to said first conveyor section; connecting means operated upon movement of said first conveyor section into engagement with said second conveyor section for connecting said first and second conveyor sections; and means for imparting reciprocating movement to said first conveyor section to (1) move said first conveyor section into engagement with the second conveyor section to connect said sections together and (2) to advance articles from said first conveyor section along said second conveyor section.

18. In apparatus for conveying articles, as set forth in claim 17: means for disabling said connecting means to allow said first and second conveyor sections to be separated.