Performance dependence of CMOS on silicon substrate orientation for ultrathin oxynitride and HfO₂ gate dielectrics

Abstract

Dependence of CMOS performance on silicon crystal orientation of (100), (111), and (110) has been investigated with the equivalent gate dielectric thickness less than 3 nm. Hole mobility enhancement of ≥ 160% has been observed for both oxynitride and HfO2 gate dielectrics on (110) surfaces compared with (100). CMOS drive current is nearly symmetric on (110) orientation without any degradation of subthreshold slope. For HfO2 gate dielectrics, an approximately 68% enhancement of pMOSFET drive current has been demonstrated on (110) substrates at Lpoly = 0.12 μm, while current reduction in nMOS is around 26%.