Oxidation characteristics of nonpatterned and patterned poly-SiGe layers were evaluated to confirm the feasibility for the application of poly-SiGe to the gate electrode. Characterization of poly-SiGe after oxidation was performed using atomic force microscopy, (AFM), X-ray photoelectron spectroscopy (XPS), cross-sectional transmission electron microscopy (TEM), and energy-dispersive X-ray spectroscopy (EDS). The oxide thickness on poly-SiGe layer increased with increasing Ge content, while that on poly-SiGe (Ge 20%) sample was comparable to that of poly-Si (Ge 0%). When the Ge content was mere than 40%, two different oxide layers were observed on poly-SiGe. Intensive analyses revealed that the oxide layers were composed of SiO2-rich mixed oxide (SiO2(GeO2)) and GeO2-rich mixed oxide (GeO2(SiO2)). For the patterned poly-SiGe sample, the oxidation characteristics were similar to those of nonpatterned sample. The best sidewall oxide profile was obtained in poly-SiGe (Ge 20%) sample. Because the sidewall oxide thickness is too thick for poly-SiGe sample with more than 40% of Ge, poly-SiGe (Ge 20%) is believed to be the most suitable candidate for gate electrode material. (C) 2001 The Electrochemical Society. All rights reserved.