Patent ID: 9601574
Date: 2017-03-21
CPC Classifications: H01L

Claim:
1. A method comprising: forming a recess in a source/drain (S/D) region of a semiconductor substrate, wherein the semiconductor substrate is formed of a first semiconductor material; epitaxially growing a second semiconductor material, a third semiconductor material, and a fourth semiconductor material within the recess to form a S/D feature in the recess, wherein the fourth semiconductor material is disposed over the third semiconductor material in the recess and the third semiconductor material is disposed over the second semiconductor material in recess, wherein the second semiconductor material includes a dopant at a first concentration, the third semiconductor material includes the dopant at a second concentration, and the fourth semiconductor material includes the dopant at a third concentration, wherein the first concentration is less than the second concentration and the second concentration is greater than the third concentration; and removing a portion of the S/D feature to form a valley extending into the S/D feature.