BACKGROUND

As microelectronic technology advances for higher performance, integration of high performance transistor devices, such as CMOS transistors devices, becomes increasingly important. CMOS transistor improvement may involve controlling the strain state of the transistor channel. Within a CMOS device, an NMOS transistor portion and a PMOS transistor portion may require differing types of channel strain requirements. For example, the NMOS channel may require a tensile strain in the channel region, while the PMOS channel may require a compressive strain in the channel region.

