Throughput and production data on the GSD-HE using the continuous variable aperture

Chained implants are becoming increasingly prevalent on Axcelis' GSD-HE series implanters. Chain implants can offer a number of advantages over traditional single implants including reduced particle counts, increased operator efficiency, and increased throughput. When performing chain implants the tune times, rather than the wafer handling times, limit tool throughput. Therefore, the Continuous Variable Aperture (CVA) upgrade was introduced to decrease tune times in chain implants. When using the CVA in a chain the extraction conditions are kept constant and the CVA controls the beam current by attenuating the beam. This reduces average tune times between recipes from over two minutes to less than fifty seconds. Production data has been collected for a four month period before, and a two month period after, the installation of a CVA on an GSD-HE implanter running >75% chained implants. The evaluation demonstrated that the CVA has no negative impact on any measurable parameter including source life, particle counts, tool availability or yield. Data collected during two weeks of marathon throughput testing show that, on average, a chain using the CVA will operate 20% faster than the same chain without the CVA. In addition, the throughput improvement from unchained implants to a chain with the CVA can be >50%.