Novel Process Development for Bilayer Embedded SiGe Source/Drain Formation

We have developed a new technique of bilayer embedded SiGe epitaxy in order to suppress the degradation of short channel characteristics in PFETs. We have found that the SiGe growth rate near the recess side wall increased when using a high SiH 2 Cl 2 flow at high pressure. It enabled 1st conformal undoped SiGe layer growth for the recess shape. For the 2nd SiGe layer, we used an appropriate B 2 H 6 flow rate for good morphology. XAFS revealed that the 2nd nearest neighbors of Ge became distorted when the incorporated amount of B increased. In addition, we developed a Simultaneous condition switching technique for forming bilayer embedded SiGe.