The present disclosure provides a method of fabricating that includes 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 an first etching to form a recess in the substrate, where the first etching removes a portion of the doped region; performing a second etching to expand the recess in the substrate, where the second etching includes an etchant and a catalyst that enhances an etching rate at a remaining portion of the doped region; and filling the recess with a semiconductor material.