a semiconductor device has recesses formed in the substrate during removal of the anti - reflective coating because these recess locations are exposed during the etching of the arc . although the etchant is chosen to be selective between the arc material and the substrate material , this selectivity is limited so that recesses do occur . a problem associated with the formation of these recesses is that the source / drains have further to diffuse to become overlapped with the gate . the result is that the transistors may have reduced current drive . the problem is avoided by waiting to perform the arc removal until at least after formation of a sidewall spacer around the gate . the consequent recess formation thus occurs further from the gate , which results in reducing or eliminating the impediment this recess can cause to the source / drain diffusion that desirably extends to overlap with the gate .