Mobility enhancement by strained channel CMOSFET with single workfunction metal-gate and fabrication method thereof

A method of forming a complementary MOSFET consisting of a PMOSFET and an NMOSFET, comprising:

• providing a semiconductor substrate with regions of a PMOSFET and an NMOSFET;
• forming a compressively strained film overlying the PMOSFET channel;
• forming gate dielectric layers on the NMOSFET region and the compressively strained film, respectively;
• forming gate electrodes on the gate dielectric layers;
• and
• forming a cap layer overlying the NMOSFET region for producing a local tensile stress on a channel of the NMOSFET;
• wherein formation of the compressively strained film overlying the PMOSFET region comprises:
• forming an amorphous layer overlying the semiconductor substrate, including the PMOSFET and the NMOSFET regions;
• removing the amorphous layer overlying the PMOSFET region;
• and
• forming the compressively strained film overlying the PMOSFET region by selective epitaxy.