Patent ID: 7378308

Claim:
A method of forming a semiconductor structure, the method comprising: providing a semiconductor substrate comprising a first region and a second region; forming a first gate stack over the first region and a second gate stack over the second region; implanting the semiconductor substrate to form a lightly doped source/drain (LDD) region; after the step of implanting the semiconductor substrate, blanket forming a spacer liner layer; blanket forming a spacer layer on the spacer liner layer; patterning the spacer liner layer to form a first and a second spacer liner having L-shapes; patterning the spacer layer to form a first spacer over the first spacer liner and a second spacer over the second spacer liner; removing the first and the second spacers; and forming a contact etch stop layer (CESL) having a first portion over the first region and a second portion over the second region, wherein the CESL is directly on the first and the second spacer liners, and wherein the first portion has a first thickness substantially greater than a second thickness of the second portion.