A novel strained Si/sub 0.7/Ge/sub 0.3/ surface-channel pMOSFET with an ALD TiN/Al/sub 2/O/sub 3//HfAlO/sub x//Al/sub 2/O₃ gate stack

Abstract

Proof-of-concept pMOSFETs with a strained-Si/sub 0.7/Ge/sub 0.3/ surface-channel deposited by selective epitaxy and a TiN/Al/sub 2/O/sub 3//HfAlO/sub x//Al/sub 2/O/sub 3/ gate stack grown by atomic layer chemical vapor deposition (ALD) techniques were fabricated. The Si/sub 0.7/Ge/sub 0.3/ pMOSFETs exhibited more than 30% higher current drive and peak transconductance than reference Si pMOSFETs with the same gate stack. The effective mobility for the Si reference coincided with the universal hole mobility curve for Si. The presence of a relatively low density of interface states, determined as 3.3 /spl times/ 10/sup 11/ cm/sup -2/ eV/sup -1/, yielded a subthreshold slope of 75 mV/dec. for the Si reference. For the Si/sub 0.7/Ge/sub 0.3/ pMOSFETs, these values were 1.6 /spl times/ 10/sup 12/ cm/sup -2/ eV/sup -1/ and 110 mV/dec., respectively.