The mechanism of mobility degradation in MISFETs with Al/sub 2/O/sub 3/ gate dielectric

We believe that the most important task in the development of high-/spl kappa/ gate dielectrics is to engineer the interface to assure high enough mobility and reliability. Considering the 100-nm node, Al/sub 2/O/sub 3/ would appear to be the most promising candidate in terms of chemical and thermal stability, barrier offset, and compatibility with the conventional CMOS process. The integration of Al/sub 2/O/sub 3/ gate dielectrics in sub-100 nm-FETs has already been demonstrated; however, the resulting electron mobility was only a quarter the value for a FET with SiO/sub 2/ gate dielectric (D. Buchanan et al., Tech. Digest IEDM, p. 223, 2000; J.H. Lee et al., ibid., p. 645, 2000). We have clarified the mechanism by which mobility is thus degraded, both experimentally and theoretically.