Multiple polymer belt used as a carrier in a linear belt polishing system

#1. Field of the Invention

#The present invention regards a polishing pad and belt for polishing and planarizing semiconductor substrate surfaces.

#2. Discussion of the Related Art

#FIG. 1 is a side view of a known polishing system that uses a known polishing belt;

#FIG. 2 is a schematic side view of a first embodiment of a polishing belt with polishing material according to the present invention to be used with the polishing system of FIG. 1; and

#FIG. 3 is schematic exploded view of a portion of a second embodiment of a polishing belt with polishing material according to the present invention to be used with the polishing system of FIG. 1.

#As shown in FIG. 2, one embodiment of a support belt 200 according to the present invention includes an interior layer 202 made of a polymer, such as Mylar, and an exterior layer 204 made of a polymer also, such as Mylar. The interior and exterior layers 202 and 204 are preferably identical in shape defining a rectangle having a length of approximately 93.25″, a width of approximately 13″ and a thickness ranging from 7 mil to 14 mil, preferably approximately 14 mil. The polymers used for the layers 202, 204 preferably have a high tensile modulus and have a stretch resistance such that they do not require reinforced internal layers, such as fibers, metal wires or woven carcass, that are often used in conventional molded polymeric belt polishing pads. Note that while it is preferred that the polishing belt does not use reinforcing materials, it is possible to adapt the polishing belt so that one or both of the layers 202, 204 are steel reinforced such as by using metal wire. Such reinforcement would make the polishing belt stretch resistant during stress situations and would also require layers 202, 204 to be thickened.

#The polishing belt is formed by placing the two free ends 206, 208 of the interior layer 202 adjacent to one another as shown in FIG. 2. The free ends 206, 208 abut one another so as to define a linear “butted” seam 210. Such a butted seam includes the cases where the free ends 206, 208 touch one another or the free ends 206, 208 are separated from one another by a gap that ranges from zero to a maximum of 3/32″. At this stage, an adhesive 212 is placed over the entire exterior surface 214 of the interior layer 202. The adhesive 212 is a high shear adhesive preferably in the form of a roll, such as the adhesives known by the trade names Adchem 7332, Adchem 1666-2, Adchem 732, Adchem 728, PSA5, PSA12 and VHB. After the adhesive 212 is attached to the interior layer 202, a surface 215 of the exterior layer 204 is placed on the surface of the adhesive 212 facing away from the exterior surface 214 of the interior layer 202 so that the exterior layer 204 is attached to the adhesive 212. The adhesive 212 covers the entirety of the surface 215. The free ends 216, 218 of the exterior layer 204 abut one another to form a linear butted seam 220 that is similar in structure to the butted seam 210 described previously. As shown in FIG. 2, the seams 210 and 220 are opposite one another in that the seams 210 and 220 are displaced by 180° relative to one another. The displacing of the seams 210 and 220 in this manner allows for the full amount of shear to take place for the support belt 200. Note that other displacements of the seams 210 and 220 are possible where the displacements range from 180° to a minimum displacement. Preferably, the minimum displacement between the seams is approximately 4″ or 15.4°. The larger the displacement becomes with respect to the minimum displacement of 4″ the less likely the seams will move at the same time.

#Besides providing a full amount of shear, the support belt 200 provides other advantages. For example, the use of butted seams that are opposite one another allows for a uniformly thick belt even at the seams 210 and 220, where the free ends of the layers 202, 204 are not directly attached to one another and do not form raised areas, and so acts as a seamless belt. Another advantage is having the adhesive 212 cover the entire exterior surface 214 dramatically increases the shear strength of the belt when compared with the case of when the adhesive was applied only at the seams 210 and 220. Another advantage of the support belt 200 is that it does not require any altering of the belt material as far as cutting or grinding the areas around the seam in order to achieve a more uniform belt. The lack of cutting and grinding eliminates extra preparatory steps, which results in a simple design for the belt and a belt that is inexpensive to manufacture.