Investigation of SOI Substrates Incorporated with Buried MoSi₂ for High Frequency SiGe HBTs

Highly arsenic-doped Si-on-insulator (SOI) substrate incorporated with buried MoSi₂ layers is fabricated aiming at decreasing the collector series resistance of SiGe heterojunction bipolar transistors (HBTs) on SOI, thereby enhancing cutoff frequency (f_T) performance and increasing the maximum value of f_T (f_TMAX). The f_T performance at medium current is enhanced and current required for f_T=15GHz is reduced by half. The value of f_TMAX is improved by 30%.