CMP, automation, other hurdles still confront 300-mm transition, conference hears
By Jack Robertson
Semiconductor Business News
(12/02/99, 11:45:09 AM EDT)
TOKYO -- As global 300-mm wafer development heads into the home stretch, a gaggle of technical issues -- from chemical mechanical planarization (CMP) to fab automation -- remain to be solved, the Semicon Japan technical symposium heard here Wednesday.
Kenichi Kawashima, director of manufacturing technology for Selete, Japan's 300-mm consortium, believed the remaining technical problems will be resolved by the time the first 300-mm fabs are constructed in the next few years.
Semiconductor 300, the Infineon Technologies-Motorola joint pilot line in Dresden, Germany, has already produced limited production quantities of 64-megabit DRAMs, but officials said some process areas need improvement before full-scale production can begin.
Karl Mautz, a member of Motorola Semiconductor Products Sector's technical staff at Semiconductor 300, also said in a prepared paper that the remaining problems present no major barrier to ramping up 300-mm wafer production.
Among the thorny 300-mm process areas identified at the Semicon Japan session is the issue of CMP tools. Officials at both Selete and Semiconductor 300 said that 300-mm CMP tools were "very late in development" and currently trail other 300-mm equipment in maturity. Selete's Kawashima said "CMP has lower performance results than targeted and great development efforts are being made to catch up with target specifications."
Front owning unified pods (FOUPs) have experienced problems with door openings and sealings, particles generated by door latch movement, and slot spacing uniformity, Mautz said. "Transport of wafers into and out of the FOUP is a key challenge," he added.
Factory automation standards for all 300-mm processes are still not complete, which is presenting major difficulties on Selete's and Semiconductor 300's test lines. Selete and International Sematech have been working to come up with common standards in factory automation handling systems and software. The two groups met again at Semicon Japan to discuss how joint standards activities could be expanded.
Diffusion of 300-mm wafers still has some problems in across-boat film deposition and temperature non-uniformity, according to Motorola's Mautz. n ion implant, wafer loading has been a concern, he added.
Backside wafer contamination is getting increased attention in many process areas. Selete said lithography operations "face a major challenge to eliminate backside particle contamination affecting the chuck.” A similar backside contamination problem affects CVD/PVD operations.
Ion implant is also a concern in wafer handling and FOUP stockers, due to mechanical and software limitations, researchers reported.
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