Growth and Processing of Relaxed-Si1-xGex/Strained-Si Structures for Metal-Oxide Semiconductor Applications

Abstract

Epitaxial growth and processing issues related to strained-Si metal-oxide semiconductor field effect transistor (MOSFET) fabrication are discussed. The material quality of the graded Ge composition, relaxed- Si_{1- x} Ge _x buffer layers is analyzed. The ion implants used to form complementary metal-oxide semiconductor (CMOS) “wells” prior to epitaxy are found to degrade the quality of these layers by introducing a high density of misfit dislocation nucleation sites. Rough surface morphology, short misfit dislocation line lengths, and high threading defect densities are correlated with the increased nucleation site density. In addition, the oxidation of strained Si is investigated by Rutherford backscattering and Raman spectroscopy. No measurable strain relaxation is found as a result of thermal oxidation at temperatures up to 850° C.