According to US 5,593,344, a known polishing fixture includes a continuous belt, a polishing pad adhered to the belt, and multiple rollers over which the belt revolves in a continuous belt movement. The polishing pad is comprised of a single piece pad or, alternatively, multiple, individual pad sections that are positioned adjacent to one another across an outer surface of the belt. As the belt revolves, the polishing pad moves to polish and planarize one or more semiconductor wafers that are held against the polishing pad.

Unfortunately as the belt revolves over the curved surface on each the rollers, each pad section bends to correspond to the curvature of the belt rollers. Repeated bending of the pad sections places a significant amount of stress on the pad. This stress results in stretching and bunching up of an adhesive layer between the belt and each of the pad sections, which can lead to delamination of the pad sections from the belt. Consequently, a need exists for a polishing belt with a polishing pad that is less likely to stretch, bunch up, and/or delaminate when curved around rollers or other non-planar features of a semiconductor polishing fixture.

According to the invention, a polishing pad adapted for mounting on a belt is provided with a seam joint between opposed edge portions of the pad, which decreases the likelihood of stretching, bunching up, and/or delaminating of an adhesive layer between the belt and the pad.

Embodiments of the invention will now be described by way of example with reference to the accompanying drawings, according to which: Figure 1 is a perspective view representative of a polishing belt fixture that includes a known polishing pad; Figure 2 is a top plan view of a known polishing pad adhered to a polishing belt; Figure 3 is a side plan view of a known polishing pad adhered to a polishing belt.

Figure 4 is a side plan view of a known polishing pad of which polishing pad sections have become delaminated from the belt; Figure 5 is a side plan view of an exemplary polishing pad fixture that includes an exemplary polishing pad and belt;

Figures 6-8 are respective side plan views of reinforced seam joints between pad sections or between pad ends of exemplary embodiments of the polishing pad and belt of the present invention.

Figures 9 and 10 are respective side plan views of alternative configurations of seam joints for exemplary embodiments of the polishing pad; Figure 11 is representative of a side plan view of an exemplary embodiment of a polishing pad that includes parallel stress relief grooves.

Figure 1 discloses that integrated circuits are typically fabricated from semiconductor substrates or semiconductor wafers 18. The surfaces of semiconductor wafers 18 are finely polished and planarized using chemical mechanical polishing (CMP) processes. Many of these polishing CMP processes use a polishing fixture 10 that includes a polishing belt 14. Figure 1 discloses a polishing fixture 10 that includes a polishing belt 14 that is configured to revolve over a plurality of belt rollers 16. The belt 14 includes a polishing pad 12 adhered thereto. The polishing pad 12 has individual pad sections 20 that are adjacent to each other across the outer surface of the belt 14. As the belt 14 moves, each of the sections 20 is operative to polish and planarize one or more semiconductor wafers 18 that are held adjacent the polishing pad 12.

Figure 2 discloses a known polishing belt 14 with a polishing pad 12 adhered thereto. The polishing pad 12 includes independent sections 20. Figure 3 discloses that each prior art polishing pad section 20 includes a corresponding independent adhesive layer 32 that is operative to adhere the polishing pad section 20 to the surface of the belt 14. Unfortunately the revolving configuration of the belt 14 over belt rollers 16 requires that each of the pad sections 20 periodically bend to correspond to the curvature of the belt rollers 16. Bending of the pad 12 and of the pad sections 20 places a significant amount of stress on the pad 12. This stress results in stretching and bunching up of the adhesive layers 32 between the pad 12 and the belt 14 which can lead to delamination of the sections 20 of the pad 12 from the belt 14.

Figure 4 discloses the belt 14 curving around a roller 16, which has caused delamination. The opposed edge portions 38 and 40 of the sections 20 have lost their adhesive connection with the belt 14. Such delamination can significantly reduce the expected operational lifetime of the polishing pad 12 and can degrade the polishing performance of the pad 12. Consequently, there exists a need for an improved polishing

belt 14 with a polishing pad 12 that is less likely to stretch, bunch up, and/or delaminate when curved around rollers 16 or other non-planar features of a semiconductor polishing fixture 10.

The invention provides a polishing pad 12 and belt 14 for polishing semiconductor wafers 18, which includes features for maintaining a strong bond with the polishing pad 12 and belt 14. Further, features of the invention are operative to reduce the likelihood of stretching the adhesive layer 32 between the polishing pad 12 and the belt 14. Further, features of the invention reduce the likelihood of bunching up of an adhesive layer 32 between the polishing pad 12 and the belt 14. Further, features of the invention reduce the likelihood of delamination of portions of the polishing pad 12 from the belt 14. Further, features of the invention maintain adhesion between the polishing pad 12 and the belt 14, as the belt 14 and polishing pad 12 bend around a belt roller 16.

An exemplary embodiment includes, a semiconductor polishing belt 14 that includes a delamination resistant polishing pad 12 bonded thereto. In one exemplary embodiment the polishing pad 12 includes a plurality of adjacent polishing pad sections 20 that are bonded to the outer surface of the belt 14. In an alternative exemplary embodiment the polishing pad 12 is comprised of a single polishing pad section 20 that is bonded to the outer surface of the belt 14. Such a single polishing pad section 20 has a length that corresponds to the outer circumference of the belt 14.

In another exemplary embodiment the belt 14 is comprised of a stainless steel mesh in the shape of a continuous loop that is operatively flexible for traveling around rollers 16 of a polishing pad fixture. The polishing pad sections 20 in the exemplary embodiment are comprised of a flexible and elastic polymer such as a polyurethane. The polishing pad sections 20 are machine laminated to the outer surface of the belt 14 with an adhesive layer 32 comprised of an adhesive such as a flexible double-sided pressure sensitive or contact adhesive. In the exemplary embodiment with multiple pad sections 20 bonded to the belt 14, the seam joints 56 between adjacent pad sections 20, include features which decrease the likelihood of the adhesive layer 32 stretching, bunching up, and/or delaminating. In the exemplary embodiment of the present invention with a single polishing pad 12 bonded to the belt 14, the seam joint 56 between adjacent ends of the pad 12, include features which decrease the likelihood of the adhesive layer 32 stretching, bunching up, and/or delaminating

In one exemplary embodiment these features include a polishing pad 12 with adjacent edges of pad sections 20 or pad ends that are cooperatively beveled or dovetailed to interlock and/or overlap with each other. In other exemplary embodiments the seam joints 56 between adjacent pad sections 20 or pad ends are reinforced with a caulking material such as an elastic polymer. By reinforcing the seam joints 56, with interlocking or overlapping seams and/or caulking the present exemplary invention is operative to prevent the adhesive layer 32 from stretching and/or delaminating from the belt 14 as the polishing pad 12 of the belt 14 curves around belt rollers 16 or other non-planar features of a polishing fixture 10.

In other exemplary embodiments of the present invention, the polishing pad 12 includes a plurality of parallel grooves spaced across the width of the pad 12 in a transverse direction with respect to the direction of movement of the polishing belt 14.

The grooves are operative to further relieve stress on the polishing pad 12 and minimize the occurrence of pad 12 delamination as the polishing pad 12 bends responsive to the curvature of a belt roller 16.

Referring now to the drawings and particularly to Figure 5, there is shown therein a side plan view representative of an exemplary semiconductor polishing fixture 10 that includes an exemplary polishing pad 12 and belt 14 of the present invention. This described polishing fixture 10 is representative of a polishing pad apparatus, which includes two belt rollers 16. However, alternative exemplary embodiments of the pad 12 and belt 14 may be used with other polishing fixtures with a plurality of belt rollers 16 of various sizes, configurations, and orientations, including the polishing fixture 10 shown in Figure 1.

The polishing fixture 10 further includes a semiconductor support 208, that is operative to place a semiconductor wafer 18 adjacent the polishing pad 12 and belt 14 of the present invention. The exemplary polishing fixture 10 further includes a base 212 on the opposite side of the pad 12 and belt 14 as the semiconductor wafer 18. The base 212 is operative to prevent the relatively planer surface of the pad 12 and belt 14 that is adjacent the semiconductor wafer 18 from being deformed by the downward force of the semiconductor support 208.

The exemplary embodiment of the polishing pad 12 and belt 14 for use with the polishing fixture 10 has an inner circumference of between 90 and 110 inches. The

exemplary width of the belt 14 is between 20 and 40 inches. However, it is to be understood that alternative embodiments of the pad 12 and belt 14 may have other sizes based on the relative dimensions of the polishing fixture 10 that the pad 12 and belt 14 is installed thereon. For example the exemplary polishing fixture 10 is shown with one semiconductor support 208; however, alternative embodiments of the exemplary pad 12 and belt 14 may have sufficient width and length to be mounted on a polishing fixture 10 that is operative to simultaneously polish a plurality of semiconductor wafers 18.

Figure 6 shows an exemplary embodiment of a polishing pad 12. The polishing pad 12 includes pad portions 20 that are adhesively bonded to a belt 14. In one exemplary embodiment the pad portions 20 are representative of discrete pad sections 20 that are placed adjacent to one another along the outer surface of the belt 14. Such pad sections 20 have lengths between 20 and 40 inches. In another exemplary embodiment the pad portions 20 are representative of opposite ends of a single polishing pad section 20 that is bonded to the outer surface of the belt 14. Such a single polishing pad section 20 has a length that corresponds to the outer circumference of the belt 14.

The exemplary belt 14 is constructed of a flexible stainless steel mesh that is operative to rotate about the belt rollers 16 at a rate of between 400 and 1000 linear feet per minute. However, alternative embodiments of the belt 14 may be comprised of other flexible materials that are resistant to stretching. The exemplary polishing pad 12 is comprised of a polyurethane, however, alternative embodiments of the polishing pad 12 may be comprised of other elastic polymer materials.

In the exemplary embodiment of the present invention a seam joint 56 between the polishing pad portions 20 is reinforced with a caulking material 58. The caulking material 58 is operative to create a flexible bond between polishing pad portions 20, which reinforces the seam joint 56. In the exemplary embodiment the caulking material 58 is comprised of an elastic polymer such as polyurethane or a uv-urethane. However, it is to be understood that the present invention encompasses any flexible caulking material 58 that is operative to bind pad portions 52 and 54 of the polishing pad 12.

By caulking the seam joints 56 between two or more polishing pad sections 20, the polishing pad 12 may be manufactured as a continuous sheet which subsequently is bonded to the belt 14, rather than bonding multiple independent pad sections 20 to the belt 14 as is done in the prior art. In one exemplary embodiment the polishing pad 12 is

machine laminated with an adhesive layer 32 that spans two or more pad sections 20 of the polishing pad 12. The adhesive layer 32 is comprised of a flexible double sided pressure sensitive or contact adhesive that is operative to bond the polishing pad 12 to the belt 14.

To provide sufficient surface area for the caulking material 58 to reinforce the seam joint 56, the pad edge portions 40 and 38 are manufactured with contours which provide a channel 68 for receiving the caulking material 58. As shown in Figure 6, one exemplary embodiment of the present invention includes a channel 68 that is rectangular in shape. In this described exemplary embodiment the width of the rectangular channel 68 is between 30 and 100 mils. Also in this described exemplary embodiment the depth of the channel 68 is between 20 and 30 mils, which is generally half the thickness of the pad 12. However, it is to be understood that the present invention encompasses any suitable dimensions for the channel 68 that are operative to provide sufficient surface area for the caulking material 58 to reinforce the seam joint 56.

Figure 7 shows an alternative exemplary embodiment of a polishing pad 12 with pad edge portions 38 and 40 that are partially beveled or angled. These exemplary contours of the pad edge portions 38 and 40 form a triangular shaped channel 68 between the upper surface 81 of the polishing pad 12 and the adhesive layer 32, which is operative to receive a caulking material 58 for reinforcing seam joint 56. Figure 8 shows another alternative exemplary embodiment of a polishing pad 12 with pad edge portions 38 and 40 that are beveled or angled between the upper surface 81 of the polishing pad 12 and the adhesive layer 32.

Although rectangular and triangular channels 68 have been described, it is to be understood that the present invention encompasses any other shape or contour of channels 68 between pad sections 20 which are operative to receive a caulking material 58 for reinforcing the section joints of polishing pads 12. Alternative embodiments of the present invention may have channels 68 with other shapes and contours including convex and concave curvatures, or any other shape that is operative to provide sufficient surface area for a caulking material 58 to provide a strong and flexible bond between pad edge portions 38 and 40 of a seam joint 56.

For the exemplary embodiment of the polishing pad 12 that is comprised of multiple polishing pad sections 20, each of the seam joints 56 between polishing pad sections 20 may be reinforced as previously described. For the exemplary polishing pad

12 that is comprised of a single polishing pad section 20 bonded to the outer circumference of the belt 14, the seam joint 56 between the opposed ends of the polishing pad 12 may be reinforced as previously described.

Figures 9 and 10 show alternative exemplary embodiments of a reinforced polishing pad 12. In these exemplary embodiments, the polishing pad 12 includes pad edge portions 38 and 40 that are cooperatively contoured to mate in an interlocking and/or overlapping relation with each other. For example in Figure 9, polishing pad 12 includes two pad portions 20 with corresponding pad edge portions 38 and 40 which are cooperatively beveled or angled to interlock or overlap. Such an exemplary configuration is operative to reinforce the seam joint 56 between pad portions 20 and prevent the polishing pad 12 from delaminating from the belt 14.

Figure 10 is representative of another exemplary embodiment of a polishing pad 12 with pad edge portions 38 and 40 which are cooperatively dovetailed. Each of these described exemplary interlocking and/or overlapping features of the present invention are operative to reinforce the seam joints 56 between adjacent pad sections 20 or pad ends which minimizes the stretching, bunching up and delamination of the polishing pad 12.

In these described exemplary interlocking and/or overlapping seam joint 56 embodiments an adhesive layer 32 may not only be used to bond the polishing pad 12 to the belt 14, but may further be applied between adjacent pad edge portions 38 and 40 of the seam joints 56. Also as previously described a caulking material 58 comprised of an elastic polymer such as a polyurethane for example may also be applied between the adjacent pad edge portions 38 and 40 of each interlocking and/or overlapping seam joint 56. In addition, the present invention further comprises other configurations and contours of interlocking and/or overlapping edge portions 38 and 40 including cooperatively concave and convex curved contours and shapes.

Figure 11 is representative of another exemplary embodiment of a polishing pad 12 bonded to a belt 14 of the present invention. Here the polishing pad 12 includes a polishing layer 118 with a plurality of parallel grooves 122 in an upper surface 124 of the polishing layer 118. As with the previously described embodiments, the polishing pad 12 includes an adhesive layer 32 that is operative to bond the polishing pad 12 to a belt 14..

In the exemplary embodiment each of the grooves 122 are orientated transversely with respect to the direction of movement 130 of the belt 14. However alternative exemplary

embodiments of the polishing pad 12 may include grooves that are orientated along the surface 124 of the polishing pad 12 at other angles. As the polishing pad 12 curves around a belt roller 16, the grooves 122 enable the polishing pad 12 to relieve stresses on the adhesive bond between the polishing pad 12 and belt 14. Relief of this stress minimizes the stretching, bunching up and delamination of the adhesive layer 32 that occurs in prior art designs.

In the exemplary embodiment the grooves range between about 5 and 45 mils in depth. The width of the grooves range between about 5 and 60 mils and each groove is spaced every 50 to 500 mils along the top surface 124 of the polishing pad 12. In this described exemplary embodiment the grooves have planar vertical side walls that are normal to the top surface of the pad 12. However, alternative embodiments may have angled and/or curved walls depending on the dimensions of the pad 12 and the expected amount of curvature that the pad 12 will undergo when moving over a belt roller 16.