Method of fabricating semiconductor devices

Abstract

A method of fabricating a semiconductor device is provided. The method includes forming a gate having a first material on a substrate and a layer of a second material overlaying the gate. Sidewall spacers are formed on opposite sides of the gate. A characteristic of a portion of the substrate between adjacent sidewall spacers is changed using the layer of second material and the sidewall spacers as a mask. An isotropic wet etch process is performed to remove the substrate portion with a changed characteristic to form a recess in the substrate. An orientation selective wet etching process is performed on the recess to shape the inner walls of the recess into sigma-shape. Changing a substrate characteristic in conjunction with isotropic wet etching prevents the substrate from being damaged, and therefore can obtain defect free epitaxial SiGe growth performance.