Defect Reduction for Formation of Epitaxial Layer in Source and Drain Regions

摘要

The embodiments of mechanisms for forming source/drain (S/D) regions of field effect transistors (FETs) described enable forming an epitaxially grown silicon-containing layer with reduced number of particles on surface of recesses. The described mechanisms also reduce the effect of the residual particles on the epitaxial growth. The mechanisms include controlled etch of a native oxide layer on the surfaces of recesses to reduce creation of particles, and pre-CDE etch to remove particles from surface. The mechanisms also include reduced etch/deposition ratio(s) of initial CDE unit cycle(s) of CDE process to reduce the effect of residual particles on the formation of the epitaxially grown silicon-containing layer. With the application of one or more of the mechanisms, the quality of the epitaxial layer is improved.

主权项

1. A method of forming a semiconductor device, the method comprising:
forming a gate structure over a substrate; removing portions of the substrate to form recesses adjacent to the gate structure; and performing an asymmetric cyclic deposition and etching (CDE) process to form an epitaxial layer in the recesses, wherein initial CDE unit cycles have a lower etch to deposition ratio than one or more subsequent CDE unit cycles.