Patent ID: 8343872

Claim:
A method of fabricating a semiconductor device, comprising: providing a semiconductor substrate; forming a gate structure on the substrate; performing an implantation process to form a doped region in the substrate; forming spacers on sidewalls of the gate structure; performing a first etching to form a recess in the substrate, wherein the first etching removes a portion of the doped region; performing a second etching to expand the recess in the substrate, wherein the second etching includes an etchant and a catalyst that enhances an etching rate at a remaining portion of the doped region and results in a profile of the recess that includes two adjacent sidewalls, the two adjacent sidewalls including a first sidewall and a second sidewall and having different angles as measured with respect to an axis parallel to a surface of the substrate, neither of the two adjacent sidewalls being parallel to the axis, the first sidewall being closer to the surface of the substrate and having an angle that does not exceed 90 degrees as measured with respect to the axis; and filling the recess with a semiconductor material.