US Patent 7696578 Selective CESL structure for CMOS application

A PMOS device less affected by negative bias time instability (NBTI) and a method for forming the same are provided. The PMOS device includes a barrier layer over at least a portion of a gate structure, a gate spacer, and source/drain regions of a PMOS device. A stressed layer is then formed over the barrier layer. The barrier layer is preferably an oxide layer and is preferably not formed for NMOS devices.