Patent ID: 8247850
Filing Date: 2012-08-21
Classification: H01L

Abstract:
1. A method for making a semiconductor device, the method comprising: providing a substrate having a first gate structure and a second gate structure thereon; forming an underlayer over the first gate structure and the second gate structure; removing the underlayer from the first gate structure; forming a first stressor layer over the first gate structure and the second gate structure wherein the first stressor layer is in contact with the first gate structure and in contact with the underlayer over the second gate structure; removing the first stressor layer from the second gate structure with a first etch that uses the underlayer as an etch stop layer; removing the underlayer from the second gate structure; forming a second stressor layer in contact with the first stressor layer over the first gate structure and in contact with the second gate structure; wherein the underlayer comprises a first sub-layer of a first material and a second sub-layer of a second material, wherein the first material and the second material are distinct materials.