Patent ID: 8536001

Claim:
A method for forming a semiconductor device, comprising: providing a substrate having a gate structure and first spacers on both sidewalls of the gate structure formed on a top surface of the substrate; forming first openings in the substrate by using the first spacers as a mask, wherein the first openings are located on both sides of the gate structure; forming second openings by etching a sidewall of the first openings in a direction toward the gate structure with an etching gas, wherein each of the second openings is an extension of a corresponding one of the first openings underneath an adjacent first spacer of the first spacers; performing an annealing process to the first openings and the second openings; and forming epitaxial layers in the first openings and the second openings, wherein each of the first openings and the second openings has a size and a location to determine a stress and a distance between the epitaxial layers in the second openings and subsequently-formed source/drain regions.