DEVICE PERFORMANCE CONSIDERATIONS OF NPN HBTS DUE TO ELEVATED OXYGEN IN SUB-50 NM SIGE AND SIGEC BASE LAYERS GROWN BY LPCVD

摘要

Process related device performance issues are identified, which result from elevated oxygen in boron doped SiGe and SiGeC base layers of NPN HBTs (heterojunction bipolar transistors). Oxygen is shown to affect film parameters such as boron incorporation, sheet resistance, and minority carrier lifetime, all of which impact device performance. From these studies an "oxygen threshold" for minimizing adverse effects to device performance is suggested. Oxygen levels were determined with secondary ion mass spectrometry (SIMS) and sheet resistance by four-point probe (FPP). The sub-50nm SiGe and SiGeC films were grown by LPCVD (low pressure chemical vapor deposition) in an AMAT 5200 Centura epi reactor.