Rohm and Haas introduces polyurethane polishing pads

By Liz White, UT staffCMP Technologies, a unit of Rohm and Haas Electronic Materials, has introduced a new polishing pad, based on a proprietary polyurethane formulation, which it describes as "the industry's first … to combine the benefits of hard and soft pads for advanced CMP (chemical mechanical planarisation) applications."CMP is a process used in the microelectronics sector for finishing, or smoothing, the surface of devices such as silicone chips or, in this case, copper wafers. CMP materials are used to, "create the flawless surfaces required to make faster and more powerful integrated circuits and electronic substrates," according to a company statement. Flat, completely planar surfaces are vital in this sector, and are getting harder to achieve as wafer size and the number of metal layers increases. The new product, called VisionPad VP3100, provides "excellent planarisation capability and low defectivity during volume production of copper wafers," claims Rohm and Haas. This raises throughput and reduces costs, the group added. VisionPad VP3100's polyurethane formulation gives a softer surface than a traditional hard pad. This reduces defects but also maintains "the rigidity needed to deliver good planarisation during CMP in copper barrier processes," the firm's press release said. Beyond stating that the pad uses "a new group of polymer chemistries, Rohm and Haas revealed no furter details of the PU formulation, but stated that this advanced pad technology "improves die yields through minimisation of scratches and chatter marks across the wafer." Pad life is equivalent to the industry standard hard pad and surpasses that of the industry standard soft pad, Rohm and Haas claims. The new pad is in production at Asian foundries and at a European device manufacturer and will be commercially available in January 2006."As customers move toward 65nm node device production, they're experiencing yield losses from defects that were once tolerable. The VisionPad VP3100 polishing pad responds to this challenge by offering a low defectivity pad with superb planarisation characteristics in the copper barrier step," said Cathie Markham, vice president, Technology, Rohm and Haas Electronic Materials, CMP Technologies. As a result of our improved manufacturing process, we are able to deliver a highly consistent product to our logic, IDM and foundry customers that allow them to integrate the VP3100 pad into existing processes with few modifications," Markham added. As a final bonus, Rohm and Haas said that, unlike other soft pads used, VisionPad VP3100 CMP can also be re-conditioned. Pad surface regeneration will give "optimal polishing results that are constant throughout the pad's life as well as from pad to pad." Although targeted for 65nm applications, the new pad can be used for current 130nm and 90nm processes."