Bulk Material Analysis of Wafers Processed in RIP Round Robin

Abstract

The Greater Silicon Valley Implant Users' Group (GSVIUG) has conducted several round robins to determine the uniformity and repeatability of modern rapid thermal processing (RTP) equipment. High-dose ion implants (5E15 As, 80keV) of 150mm wafers were used to monitor temperature distribution. Sheet resistance maps were then used to compare the uniformity and repeatability of each vendor's equipment. The results of the initial round robin evaluation showed that uniformity varied significantly with RTP vendor and implant conditions, ranging from 0.5% (one sigma/mean) to 14.0%. Vendors' RTP equipment shows a characteristics fingerprint on their sheet resistance maps, similar to the early maps of ion implant equipment. Maps from several round robins are presented that demonstrate problems with temperature distribution, chamber thermal memory, rapid edge cooling, and heat sink effects at wafer supports. Recent literature has focused on the importance of the RTP time-temperature profile. The short duration and high temperature of RTP make temperature and temperature distribution critical parameters that affect both the nature of the bulk defects as well as the final results of the implant-anneal process. This paper describes the material analysis of implanted wafers processed by various RTP equipment vendors. Results provided by spreading resistance probe (SRP) and secondary ion mass spectroscopy (SIMS) are compared with sheet resistance results. Conclusions about the time-temperature profile of RTP equipment will be made.