New Graded Ge Condensation Method for Formation of Ge-on-Insulator Layer

Ge-on-insulator (GOI) metal oxide semiconductor field-effect transistors (MOSFETs) have recently re-attracted public attention as one of the candidates to replace conventional silicon devices because a germanium substrate has a higher hole and a higher electron mobility than silicon does. We propose a novel formation technique modulating the gas ratio (Si2H6/GeH4) for full depleted (FD) GOI metal insulator semiconductor field-effect transistors (MISFETs). The ratio Si2H6/GeH4 increases gradually with the growth time. Consequently, a Ge layer is successfully formed by thermally oxidizing a SiGe layer grown on a silicon-on-insulator (SOI) wafer. With this technique, the thickness of the 0fabricated Ge layer is 30 nm, which can be adjusted by using the growth time. As results, the roughness of the GOI layer had a root-mean-square (RMS) value of 0.84 nm. Furthermore, pure germanium could be found in the secondary ion mass spectroscopy (SIMS) profile. Therefore, this technique is confirmed to be extremely useful as one method to form a germanium layer, which is needed to form GOI devices. KCI Citation Count: 5