Sige Layers Defect of 28nm Node PMOSFETS In Advanced CMOS Technology

Embedded SiGe as locally strained Si technology has been used to improve pMOSFET device performance through hole mobility enhancement. Embedded SiGe is achieved by selectively growing epitaxial SiGe film in recessed Si pMOSFET source and drain areas. However, selective epitaxy of SiGe will be increasingly challenging as germanium concentrations increase. The emerging problems include poly line SiGe residue, poly top SiGe residue and NMOS area SiGe residue, which are three major killers for device yield. In this paper, these three defects are detailed investigated, the formation mechanisms are discussed and the proper solutions are suggested.