RPCVD를 이용한 실리콘 게르마늄 이종 접합 바이폴라 트랜지스터 제작 및 특성 분석

Abstract

In this paper, non-self-aligned SiGe HBTs with <TEX>${f}_\tau$</TEX> and<TEX>${f}_max $</TEX>above 50 GHz have been fabricated using an RPCVD(Reduced Pressure Chemical Vapor Deposition) system for wireless applications. In the proposed structure, in-situ boron doped selective epitaxial growth(BDSEG) and TiSi<TEX>$_2$</TEX> were used for the base electrode to reduce base resistance and in-situ phosphorus doped polysilicon was used for the emitter electrode to reduce emitter resistance. SiGe base profiles and collector design methodology to increase <TEX>${f}_\tau$</TEX> and<TEX>${f}_max $</TEX> are discussed in detail. Two SiGe HBTs with the collector-emitter breakdown voltages <TEX>${BV}_CEO$</TEX> of 3 V and 6 V were fabricated using SIC(selective ion-implanted collector) implantation. Fabricated SiGe HBTs have a current gain of 265 ∼ 285 and Early voltage of 102 ∼ 120 V, respectively. For the <TEX>$1\times{8}_\mu{m}^2$</TEX> emitter, a SiGe HBT with <TEX>${BV}_CEO$</TEX>= 6 V shows a cut-off frequency, <TEX>${f}_\tau$</TEX>of 24.3 GHz and a maximum oscillation frequency, <TEX>${f}_max $</TEX>of 47.6 GHz at <TEX>$I_c$</TEX>of 3.7 mA and<TEX>$V_CE$</TEX> of 4 V. A SiGe HBT with <TEX>${BV}_CEO$</TEX> = 3 V shows <TEX>${f}_\tau$</TEX>of 50.8 GHz and <TEX>${f}_max $</TEX> of 52.2 GHz at <TEX>$I_c$</TEX> of 14.7 mA and <TEX>$V_CE$</TEX> of 2 V.