Strain balanced structure with a tensile strained silicon channel and a compressive strained silicon-germanium channel for CMOS performance enhancement

摘要

A method of fabricating a CMOS device wherein mobility enhancement of both the NMOS and PMOS elements is realized via strain induced band structure modification, has been developed. The NMOS element is formed featuring a silicon channel region under biaxial strain while the PMOS element is simultaneously formed featuring a SiGe channel region under biaxial compressive strain. A novel process sequence allowing formation of a thicker silicon layer overlying a SiGe layer, allows the NMOS channel region to exist in the silicon layer which is under biaxial tensile stain enhancing electron mobility. The same novel process sequence results in the presence of a thinner silicon layer, overlying the same SiGe layer in the PMOS region, allowing the PMOS channel region to exist in the biaxial compressively strained SiGe layer, resulting in hole mobility enhancement.