By recessing drain and source regions, a highly stressed layer, such as a
contact etch stop layer, may be formed in the recess in order to enhance
the strain generation in the adjacent channel region of a field effect
transistor. Moreover, a strained semiconductor material may be positioned
in close proximity to the channel region by reducing or avoiding undue
relaxation effects of metal silicides, thereby also providing enhanced
efficiency for the strain generation. In some aspects, both effects may
be combined to obtain an even more efficient strain-inducing mechanism.