US20060135051A1

US20060135051A1 - Polishing pad with removal features

Info

Publication number: US20060135051A1
Application number: US11/017,339
Authority: US
Inventors: Christopher Meyer; Thomas Widman
Original assignee: Cabot Microelectronics Corp
Current assignee: CMC Materials Inc
Priority date: 2004-12-20
Filing date: 2004-12-20
Publication date: 2006-06-22

Abstract

The invention provides a polishing pad comprising a polishing element and an adhesive layer provided on the bottom surface of the polishing element for attaching the polishing element to a polishing device. To protect the adhesive layer and prevent unintentional adhering of the polishing element, the polishing pad is also provided with a protective liner adhered to and protectively covering the adhesive layer. To facilitate removal of the protective liner, the protective liner includes an extended pull tab and the polishing element includes an extended removal tab.

Description

FIELD OF THE INVENTION

This invention pertains generally to a polishing pad, and more particularly to a polishing pad for use in chemical-mechanical polishing.

BACKGROUND OF THE INVENTION

Polishing processes are used in the manufacture of microelectronic devices to form flat surfaces on semiconductor wafers, field emission displays, and many other microelectronic substrates. For example, the manufacture of semiconductor integrated circuit (IC) devices generally involves the formation of various process layers, selective removal or patterning of portions of those layers, and deposition of yet additional process layers on a semiconductor wafer. The IC process layers can include, by way of example, insulation layers, gate oxide layers, conductive layers, and layers of metal or glass, etc. It is generally desirable in certain steps of the IC wafer process that the uppermost surface of the process layers be planar, i.e., flat. Relatively flatter surfaces allow the use of more sensitive, higher density patterning on subsequent layers.
Chemical-mechanical polishing or planarization (“CMP”) is a process used to planarize IC wafer process layers wherein a deposited material, such as a conductive or insulating material, is polished to planarize the wafer for subsequent process steps. The process has been labeled “chemical-mechanical” because the surface of the wafer is subjected to mechanical abrasion combined with other more purely chemical action such as oxidation. The worked surface of the IC wafer is subjected to a rotating or otherwise moving pad in the presence of slurry. The slurry contains both abrasive particles and chemical activators, modulators or accelerants.
Most commercial applications of CMP rely on specialized machine tools that include a rotating pad platen, a wafer carrier and a slurry applicator. The rotating platen is upward facing, circular and adapted to receive a disk shaped pad. Like the pad platen, the wafer carrier is also equipped with a rotation mechanism. The wafer carrier is positioned over the pad. As both the wafer carrier and the pad rotate, the wafer carrier directs the worked surface of the wafer onto pad. The polishing composition (also referred to as a polishing slurry) generally is introduced onto the rotating polishing pad.
The disk shaped polishing pads typically have one side designated for contacting the wafer while the opposite side contacts the platen. An adhesive layer is included on the platen side of the pad to fix the pad to the plate. A protective liner can be adhered to the adhesive layer to protect the adhesive layer from contamination and to prevent unwanted sticking to other surfaces before installation. This protective liner is peeled off the pad before installion on the platen. This pealing step presents a difficulty, however, because clean room operators using CMP tools must wear protective gloves. Gloves make the first step of gripping the liner for removal difficult. Operators are known to address the gripping problem by using a knife or razor blade, which can result in damage to the pad.
Accordingly, there is a need for an adhesive-backed polishing pad that is better adapted for easy removal of the protective liner. There is also a need for a polishing pad that can be easily removed from the platen. The invention provides such a polishing pad and a method of manipulating a polishing pad that addresses these needs.

BRIEF SUMMARY OF THE INVENTION

The invention provides a polishing pad having a polishing element that defines an outer perimeter that may, for example, be circular in shape. To secure the polishing element to a platen, an adhesive layer is provided on a bottom surface of the polishing element. A protective liner is adhered to the adhesive layer so as to protectively cover the adhesive layer. The protective liner and adhesive layer interact together so that the protective liner can be removed and discarded while the adhesive layer remains on the bottom surface. To facilitate peeling of the protective liner from the polishing pad, a pull tab is connected to the protective liner and extends beyond the perimeter defined by the polishing element. Extending the pull tab beyond the perimeter improves the ability of an operator to securely grasp the protective liner.
To facilitate removal of the polishing element from the platen after a period of use, a removal tab is connected to the polishing element which also extends beyond the perimeter. The adhesive layer that is provided on the bottom surface of the polishing element is substantially absent from the removal tab. Accordingly, the removal tab can be grasped and pulled in a direction generally away from the platen to peel the polishing element from the platen. Moreover, the removal tab further facilitates peeling of the protective liner from the polishing pad by enabling an operator to simultaneously grasp the removal tab and pull tab and to pull the removal tab and pull tab in generally opposite directions.
Thus, an advantage of the invention is that it provides a polishing element with a protective liner having a pull tab attached which enhances an operator's ability to remove the protective liner. Another advantage is that the invention facilitates the removal of the polishing element from a polishing device. These and other advantages and features of the invention will be apparent from the drawings and detailed description provided herein.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a top perspective view of a polishing pad including a polishing element with a removal tab and a protective liner with a pull tab.
FIG. 2 is a side elevational view of the polishing pad of FIG. 1 illustrating the polishing element and protective liner being peeled apart.
FIG. 3 is a top perspective view of a polishing pad wherein the removal tab and the pull tab generally overlap.
FIG. 4 is a perspective view of a polishing pad element with a removal tab being peeled from the platen of a polishing device.
FIG. 5 is a top perspective view of an alternative view of a polishing pad wherein the removal tab and the pull tab include respective projection portions.
FIG. 6 is a side elevational view of the polishing pad of FIG. 5.

DETAILED DESCRIPTION OF THE INVENTION

Now referring to the drawings, wherein like reference numbers refer to like elements, there is illustrated in FIGS. 1 and 2 a polishing pad 100 designed in accordance with the teachings of the invention. The polishing pad 100 includes a polishing element 102 that generally defines a perimeter 104. In the preferred and illustrated embodiment, the perimeter 104 is circular in shape with a width designed by arrow 106. As will be appreciated, in the preferred embodiment of a circular polishing element 102, the width designated by arrow 106 corresponds to a diameter. However, in other embodiments, the perimeter 104 can have any other suitable shape such as, for example, square or octagonal. Furthermore, the width of the polishing element 102 as indicated by arrow 106 can be any suitable value, preferably between about 10 millimeters to about 200 millimeters.
The polishing element 102 also includes a top surface 110 and a parallel bottom surface 112, which provides the polishing element with a uniform thickness and a generally planar shape. The top surface 110 is adapted for motion adjacent to and polishing of a substrate, such as a semiconductor wafer, while the bottom surface 112 is adapted for attachment to a polishing device. Additionally, in an embodiment, the polishing element 102 may include a plurality of pores disposed into the top surface 110, the bottom surface 112, or both. Likewise, in an embodiment, the polishing element may include a plurality of grooves disposed into the top surface 110, the bottom surface 112, or both.
Referring to FIG. 1, the polishing pad 100 also includes a removal tab 120 connected to the polishing element 102 that extends in a radial direction beyond the perimeter 104 defined by the polishing element 102. Preferably, the removal tab 120 extends about 3 millimeters or more beyond the circular perimeter 104 and, more preferably, about 6 millimeters or more beyond the perimeter. In the illustrated embodiment, the removal tab 120 can have a generally parabolic shape. However, in other embodiments, the removal tab can have a crescent shape, a rectangular shape, or any other appropriate shape. The removal tab 120 has a thickness defined by spaced-apart top and bottom surfaces 122, 124 that, in the illustrated embodiment, are co-planar with the respective top and bottom surfaces 110, 112 of the polishing element 102.
The removal tab 120 can be formed integrally with the polishing element 102, or the removal tab can be formed separately from and later attached to the polishing element. The removal tab 120 and polishing element 102 can be made from any suitable material, and typically but not necessarily can be made from the same material. Typically, polishing elements of polishing pads are made from a polymer resin. Preferably, the polymer resin is selected from the group consisting of thermoplastic elastomers, thermoplastic polyurethanes, thermoplastic polyolefins, polycarbonates, polyvinylalcohols, nylons, elastomeric rubbers, elastomeric polyethylenes, polytetrafluoroethylenes, polyethyleneterephthalates, polyimides, polyaramides, polyarylenes, polyacrylates, polystyrenes, polymethylmethacrylates, copolymers thereof, and mixtures thereof. More preferably, the polymer resin is a thermoplastic polyurethane resin.
Referring to FIG. 2, to attach the polishing element 102 to a polishing device, there is disposed on the bottom surface 112 of the polishing element an adhesive provided in the form of an adhesive layer 128. The adhesive can be any suitable adhesive such as, for example, a pressure sensitive adhesive. Preferably, the adhesive layer 128 is disposed across the bottom surface 114 within the confines of the perimeter 104 such that it is substantially absent from the removal tab 120.
Referring to FIGS. 1 and 2, to protect the adhesive layer 128 and prevent the polishing pad 100 from unintentionally adhering to objects, the polishing pad 100 also includes a protective liner 130. The protective liner 130 has a first surface 132 and a parallel second surface 134 that desirably provide the protective liner with a uniform thickness. The first surface 132 can be adhered to the bottom surface 112 of the polishing element 102 by way of the adhesive layer 128 to protectively cover the adhesive layer. To facilitate removing the protective liner 130 from the bottom surface 112 when attaching the polishing element 102 to a polishing device, the protective liner is preferably made from a flexible thermoplastic or a thermoset polymer that demonstrates a substantial non-stick or peel-away characteristic. In an alternative embodiment, the protective liner is made from wax-coated paper. Accordingly, when the protective liner 130 is removed from the polishing element 102, the adhesive layer 128 will remain bonded to the bottom surface 112 of the polishing element 102.
Like the polishing element 102, the protective liner 130 defines a second perimeter 136. In the illustrated and preferred embodiment, the second perimeter 136 has the same circular shape as well as the same width as designated by arrow 106 as the first perimeter 104. Accordingly, the protective liner 130 and polishing element 102 are coterminous with each other. As such, the width of the protective liner indicated by arrow 106 can be any suitable value, preferably between about 10 millimeters to about 200 millimeters. In other embodiments, the shapes and widths could vary substantially between the protective liner and polishing element.
Connected to the protective liner 130 and extending beyond the second perimeter 136 in a radial direction is a pull tab 140. Preferably, the pull tab 140 extends about 3 millimeters or more beyond the circular second perimeter 136 and, more preferably, about 6 millimeters or more beyond the second perimeter. In the illustrated embodiment, the pull tab 140 has a generally parabolic shape similar to that of the removal tab 120. However, in other embodiments, the pull tab can have a crescent shape, a rectangular shape, or any other appropriate shape.
The pull tab 140 can be formed integrally with the protective liner 130 or it can be formed separately from and later attached to the protective liner. Additionally, the pull tab 140 can have a first surface 142 and a second surface 144 that, in the illustrated embodiment, are co-planar to the respective first and second surfaces 132, 134 of the protective liner 130. Preferably the pull tab 140 is made from the same flexible, non-stick thermoplastic material as the protective liner 130. Furthermore, the adhesive layer 128 adhering the protective liner 130 to the polishing element 102 is also substantially absent from the pull tab 140.
An advantage of providing a polishing pad having the foregoing structure is the simplified and enhanced removal of the protective liner from the polishing element. Referring to FIG. 1, because both the removal tab 120 and the pull tab 140 extend beyond the first and second perimeters 104, 136 defined by the polishing element 102 and the respective protective liner 130, the tabs are suitably exposed for grasping even by the rubber-gloved hands of an operator. As illustrated in FIG. 2, the removal tab 120 and the pull tab 140 can then be manually pulled in opposite directions as indicated by arrows 148. As will be appreciated, this results in peeling the protective liner 130 from the polishing element 102. Because of the non-stick or peel-away characteristic of the protective liner material, the adhesive layer 128 will remain on the bottom surface 112 of the polishing element 102.
Another advantage is realized in the embodiments wherein the adhesive layer is absent from the removal tab 120 and the pull tab 140. By providing the adhesive-free tabs for the operator to grasp, the operator's hands will not become adhered to or otherwise ensnarled with the polishing element 102 and protective liner 130. A related advantage is that the adhesive-free removal tab 120 provides the operator with a tab connected to the polishing element 102 that can be securely grasped. Specifically, the operator's hands can grasp around the top and bottom surfaces 122, 124 of the removal tab 120, thereby facilitating manipulation of the polishing element 102 during its application to the polishing device.
In the illustrated embodiment of the polishing pad 100, removal of the protective liner 120 is further enhanced by locating the removal tab 120 and the pull tab 140 at different locations. For example, referring to FIG. 1, the polishing element 102 includes a centroid 150. In the illustrated embodiment, the centroid 150 corresponds to the center of the circular perimeter 104. The removal tab 120 and the pull tab 130 are located at an angular offset from each other with respect to the centroid 150. Angularly offsetting the removal tab 120 and pull tab 140 increasingly exposes those tabs for enhanced grasping. Preferably, the angular offset is about 20° to about 40°, and more preferably is about 30°, which adequately exposes the tabs 120, 140 but continues to facilitate peeling of the protective liner 130 from the polishing element 102 by simply pulling the tabs in generally opposite directions, as would not be possible if the tabs were offset at an angle of about 180°.
Of course, the removal tab and the pull tab need not be located at an angular offset. Referring to FIG. 3, for example, an embodiment of the polishing pad 200 is illustrated having a polishing element 202 with a removal tab 220 and a protective liner 230 having a pull tab 240. The removal tab 220 and pull tab 240 have an angular offset of approximately 0° with respect to a centroid 250 of the polishing element 202 such that the removal tab and pull tab are substantially overlaying each other. An advantage of overlaying the removal tab 220 and pull tab 240 is the simplification and possible space reduction in packaging and distribution of the polishing pad.
Another advantage of providing a polishing pad having a polishing element with a removal tab is realized in the facilitated removal of the polishing element from a polishing device. For instance, referring to FIG. 4, there is illustrated some of the components of a polishing device 160. The polishing device 160 can include a polishing table or platen 162 on which the polishing pad 100 designed in accordance with the preferred embodiment of the invention is supported. Of course, other embodiments of the polishing device may work with the various embodiments of the inventive polishing pad. Also included, as part of the polishing device is a carrier 164 supported above the platen 162 and polishing pad 100. A substrate can be mounted and retained on the carrier 164.
To carryout the polishing operation, the carrier 164 can be rotated and/or orbited with respect to the platen 162, the platen rotated and/or orbited with respect to the carrier, or both can be rotated and/or orbited simultaneously. Additionally, for providing a polishing slurry or composition from a reservoir, the polishing device 160 can include a nozzle 166 communicating with the reservoir that delivers the polishing composition to the area of interaction between the polishing pad 100 and the substrate.
As will be appreciated, to secure the polishing pad 100 to the platen 162, the bottom surface 112 is adhered onto the platen via the adhesive layer 128. Due to the adhesive attachment, the polishing element 102 resists removal from the platen 162 during, for instance, replacement of a worn polishing element. However, as illustrated, the polishing element 102 and the perimeter 104 it defines are substantially of the same dimension as the platen 162. Accordingly, the removal tab 120 extends beyond the platen 162 and is exposed for grasping by an operator. This enables grasping and pulling the removal tab 120 in a direction generally away from the platen 162, as indicted by arrow 170, to peel the bottom surface from the platen. Hence, the removal tab 120 provides both a tab to grasp the polishing element 102 with and leverage for pulling the polishing element from the platen 162.
The removal tab need not extend beyond the platen to facilitate removal of the polishing element. For instance, it will be appreciated that in embodiments wherein the platen is substantially larger than the polishing element, the removal tab will lay adjacent the top surface of the platen. However, if the removal tab is substantially adhesive free, it can be readily grasped, lifted, and pulled from the platen in the above described manner to remove the polishing element.
Illustrated in FIGS. 5 and 6 is another embodiment of a polishing pad 300 adapted to further enhance and assist the removal of a protective liner from a polishing pad element. The polishing pad 300 includes a polishing element 302 having a top surface 310 and a parallel bottom surface 312 that desirably provides the polishing element with a uniform thickness. The polishing element 302 also defines a perimeter 304. The perimeter 304 may have any suitable shape including, for example, circular. Connected to the polishing element 302 and extending beyond the perimeter is a removal tab 320.
To attach the polishing element 302 to a polishing device, the polishing pad 300 also includes an adhesive layer 328 deposited onto the bottom surface 312 of the polishing element. Preferably, the removal tab 320 is substantially absent of adhesive.
To protect and isolate the adhesive layer 328, the polishing pad 300 also includes a protective liner 330 having a first surface 332 and a parallel second surface 334 that provides desirably the protective liner with a uniform thickness. The first surface 332 of the protective liner 330 is adhered to the bottom surface 312 of the polishing element 302 via the adhesive layer 328. The protective liner 330 also defines a second perimeter 336 that can be co-extensive with the first perimeter 304. To simplify removal of the protective liner 302, the polishing pad 300 is provided with a pull tab 340 connected to the protective liner and extending beyond the perimeter 336. Preferably, the pull tab 340 is also substantially absent of adhesive.
To further enhance grasping of the exposed removal tab 320 and pull tab 340, one or both tabs can be made substantially thicker than the components they are connected to. For example, the pull tab 340 includes a liner projection portion 342 that projects from a plane defined by the first surface 332 of the protective liner 330. The liner projection portion 342 may extend coextensively to a plane defined by the top surface 310 of the polishing element 302. An advantage of the liner projection portion 342 is that it substantially thickens the pull tab 340, thereby providing the operator with more to grasp when removing the protective liner 330. The liner projection portion 342 may be formed integrally with the protective liner 330 or separately from the protective liner and later attached thereto.
Similarly, the removal tab 320 can include a pad projection portion 322 that projects from a plane defined by the bottom surface 312 of the polishing element 302. The pad projection portion 322 may project coextensively to a plane defined by the second surface 334 of the protective liner 330. The pad projection portion 322 also substantially thickens the removal tab 320 to provide an operator with more to grasp when manipulating the polishing element. Like the liner projection portion 342, the pad projection portion 322 can be formed integrally with the polishing element 302 or formed separately and later attached thereto.
Accordingly, the invention provides a polishing pad having a polishing element, an adhesive layer for adhering the polishing element to a polishing device, and a protective liner adhered to the polishing element via the adhesive layer. To facilitate peeling the protective liner from the polishing element, the protective liner includes a pull tab and the polishing element includes a removal tab. Pulling the pull tab and removal tab in opposite directions peels the protective liner from the polishing element. Additionally, the removal tab facilitates subsequently peeling the polishing pad from a polishing device.
All references, including publications, patent applications, and patents, cited herein are hereby incorporated by reference to the same extent as if each reference were individually and specifically indicated to be incorporated by reference and were set forth in its entirety herein.
The use of the terms “a” and “an” and “the” and similar referents in the context of describing the invention (especially in the context of the following claims) are to be construed to cover both the singular and the plural, unless otherwise indicated herein or clearly contradicted by context. The terms “comprising,” “having,” “including,” and “containing” are to be construed as open-ended terms (i.e., meaning “including, but not limited to,”) unless otherwise noted. Recitation of ranges of values herein are merely intended to serve as a shorthand method of referring individually to each separate value falling within the range, unless otherwise indicated herein, and each separate value is incorporated into the specification as if it were individually recited herein. All methods described herein can be performed in any suitable order unless otherwise indicated herein or otherwise clearly contradicted by context. The use of any and all examples, or exemplary language (e.g., “such as”) provided herein, is intended merely to better illuminate the invention and does not pose a limitation on the scope of the invention unless otherwise claimed. No language in the specification should be construed as indicating any non-claimed element as essential to the practice of the invention.
Preferred embodiments of this invention are described herein, including the best mode known to the inventors for carrying out the invention. Variations of those preferred embodiments may become apparent to those of ordinary skill in the art upon reading the foregoing description. The inventors expect skilled artisans to employ such variations as appropriate, and the inventors intend for the invention to be practiced otherwise than as specifically described herein. Accordingly, this invention includes all modifications and equivalents of the subject matter recited in the claims appended hereto as permitted by applicable law. Moreover, any combination of the above-described elements in all possible variations thereof is encompassed by the invention unless otherwise indicated herein or otherwise clearly contradicted by context.

Claims

1. A polishing pad comprising:

(a) a polishing element having a perimeter;

(b) a removal tab connected to the polishing element and extending beyond the perimeter;

(c) a protective liner having a first surface adhered to the polishing element; and

(d) a pull tab connected to the protective liner and extending beyond the perimeter of the polishing element.

2. The polishing pad of claim 1, wherein the polishing element has a centroid located within the perimeter, and the removal tab and the pull tab are angularly offset from each other with respect to the centroid.

3. The polishing pad of claim 2, wherein the angle of offset is about 20 degrees to about 40 degrees.

4. The polishing pad of claim 2, wherein the removal tab and the pull tab extend about 3 millimeters or more beyond the perimeter.

5. The polishing pad of claim 2, wherein the removal tab is integral with the polishing element.

6. The polishing pad of claim 5, wherein the pull tab is integral with the protective liner.

7. The polishing pad of claim 6, wherein the protective liner has a second and perimeter, the second perimeter is coterminous with the perimeter of the polishing element.

8. The polishing pad of claim 7, wherein the perimeter of the polishing element and the second perimeter are circular.

9. The polishing pad of claim 8, wherein each of the polishing element and the second perimeter is about 10 millimeters to about 200 millimeters in width.

10. The polishing pad of claim 2, wherein the pad element and the removal tab comprise a polymer.

11. The polishing pad of claim 10, wherein the polymer is selected from the group consisting of thermoplastic elastomers, thermoplastic polyurethanes, thermoplastic polyethylenes, polytetrafluoroethylenes, polyethyleneterephthalates, polyimides, polyaramides, polyarylenes, polyacrylates, polystyrenes, polymethylmethacrylates, and thermoset polymers.

12. The polishing pad of claim 5, wherein the protective liner and the pull tab comprise a polymer.

13. The polishing pad of claim 1, further comprising an adhesive layer between the protective liner and the polishing element, the adhesive layer adhering the protective liner to the pad element.

14. The polishing pad of claim 13, wherein the adhesive layer comprises a pressure sensitive adhesive.

15. The polishing pad of claim 1, wherein the polishing element has a centroid located within the perimeter, and the locations of the removal tab and the pull tab angularly correspond to each other with respect to the centroid.

16. A method of manipulating a polishing pad comprising:

(i) providing a polishing pad including a polishing element having a bottom surface and a perimeter, a removal tab connected to the polishing element and extending beyond the perimeter, a protective liner adhered to the polishing element, and a pull tab connected to the protective liner and extending beyond the perimeter;

(ii) separately grasping the removal tab and the pull tab;

(iii) pulling the removal tab and the pull tab in generally opposite directions to peel the protective liner from the polishing element;

(iv) applying the bottom surface to a platen of a polishing device to adhere the polishing pad to the polishing device.

17. The method of claim 16, further comprising:

(v) releasing the removal tab.

18. The method of claim 17, wherein the polishing element has a centroid located within the perimeter, and the removal tab and the pull tab are angularly offset from each other with respect to the centroid.

19. The method of claim 18, further comprising:

(vi) re-grasping the removal tab; and

(vii) pulling the removal tab in a direction generally away from the platen to peel the bottom surface from the platen, thereby removing the polishing pad from the polishing device.

20. A polishing pad comprising:

(a) a polishing element having a perimeter, a top surface, and a bottom surface;

(b) a removal tab connected to the polishing element and extending beyond the perimeter, the removal tab including a pad projection portion projecting from the bottom surface;

(d) a pull tab connected to the protective liner and extending beyond the perimeter of the polishing element, the pull tab including a liner projection portion projecting from the first surface.