Method of fabricating semiconductor devices including PMOS devices having embedded SiGe

摘要

A method of fabricating semiconductor device is provided. First, a recess having a substantially rectangular cross section is formed in a substrate. Then, oxide layers are formed on sidewalls and bottom of the recess by oxygen ion implantation process, wherein oxide layer on sidewalls of recess is thinner than oxide layer on bottom of recess. Thereafter, oxide layer on sidewalls of recess is completely removed, and only a portion of oxide layer on bottom of recess remains. Then, sidewalls of recess are shaped into Σ form by orientation selective wet etching using oxide layer remained on bottom of recess as a stop layer. Finally, oxide layer on bottom of recess is removed. By forming oxide layer on bottom of recess and using it as stop layer in subsequent orientation selective wet etching, the disclosed method can prevent a Σ-shaped recess with a cuspate bottom.

主权项

1. A method of fabricating a semiconductor device, the method comprising:
forming a gate medium layer on a substrate; forming a gate on a top side of the gate medium layer; forming a mask layer on the gate; forming sidewall spacers on two sides of the gate and on the top side of the gate medium layer; and performing a dry etching process on the substrate using the mask layer and the sidewall spacers as a mask to form a first recess in the substrate; performing an oxygen ion implantation process to form side oxide layers on sidewalls of the first recess and to form a bottom oxide layer on a bottom of the first recess; performing a first isotropic wet etching process to completely remove the side oxide layers and to partially remove the bottom oxide layer to form a remaining oxide layer; performing orientation selective wet etching using the remaining oxide layer as a stop layer, so as to form a shaped recess in a remaining substrate; and performing a second isotropic wet etching process to remove the remaining oxide layer.