ALD metal-gate/high-/spl kappa/ gate stack for Si and Si/sub 0.7/Ge/sub 0.3/ surface-channel pMOSFETs

ALD high-/spl kappa/ dielectrics and TiN metal-gate were successfully incorporated in both Si and Si/sub 0.7/Ge/sub 0.3/ surface-channel pMOSFETs. The high-/spl kappa/ gate dielectrics used included Al/sub 2/O/sub 3//HfAlO/sub x//Al/sub 2/O/sub 3/, Al/sub 2/O/sub 3//HfO/sub 2//Al/sub 2/O/sub 3/ and Al/sub 2/O/sub 3/. The Si transistors with Al/sub 2/O/sub 3//HfAlO/sub x//Al/sub 2/O/sub 3/ showed a sub-threshold slope of 75 mV/dec. and a density of interface states of 3/spl times/10/sup 11/ cm/sup -2/ eV/sup -1/. No obvious degradation of the Si channel hole mobility was observed. The Si/sub 0.7/Ge/sub 0.3/ pMOSFETs with the various high-/spl kappa/ gate dielectrics demonstrated enhanced transconductance, drive current and channel hole mobility compared with the Si reference.