Study of High-Ge-Content Si0.16Ge0.84 Gate Stack by Low Pressure Oxidation

Abstract

In this study, we employed low-pressure oxidation (LPO) to achieve a high-quality dielectric gate stack on high-Ge-content (HGC) Si0.16Ge0.84. According to X-ray photoelectron spectroscopy depth-profiling results, lowering the oxidation pressure can drive out-diffusion of Si atoms from the HGC SiGe surface, resulting in the suppression of GeOx formation. A nearly GeOx-free interfacial layer detected at an O-2 pressure of 0.01 torr at 600 degrees C was used. Consequently, the formation of stable SiOx resulted in the improvement of D-it and gate leakage current, which in accumulation (V-FB-1V) was also considerably reduced with an equivalent oxide thickness of 1.5 nm. Finally, by applying the LPO process and optimized process conditions, the interface trap density (D-it) was reduced to 2 x 10(12) eV(-1) cm(-2). (C) 2018 The Electrochemical Society.