Achieving a SiGe HBT epitaxial emitter with novel low thermal budget technique

Abstract

Studies of low frequency 1/ f noise show that the key to reduce 1/ f noise is to reduce/eliminate interfacial oxides at the base–emitter interface. It was reported that an epitaxial silicon emitter has led to record 1/ f noise performance due to the lack of noise inducing oxide at the base–emitter interface. In addition, epitaxial emitter also has the advantage of lowering the emitter resistance improving the transistor drivability. We report, to our best knowledge, for the first time that an epitaxial emitter with interfacial oxygen and carbon levels below the SIMS detection limit (<5×10 17 cm −3) was achieved with interruption between the SiGe base–emitter using production proven single wafer epitaxy reactor. The novelty of this process is ASM’s proprietary E 3 Solution™, which enables extremely low thermal budget treatment immediately prior to emitter deposition. Using this novel technique, the underlying metastable SiGe base layer remains completely strained and the boron profile unchanged (as determined by SIMS).