High-frequency response of 100 nm integrated CMOS transistors with high-K gate dielectrics

Abstract

This paper reports, for the first time, the high-frequency response of NMOS and PMOS transistors in an integrated CMOS technology with 100 nm physical gate length and alternative gate dielectrics such as ZrO/sub 2/ and HfO/sub 2/ with TiN/PolySi gate electrode. It is shown that the dielectric constants of ZrO/sub 2/, HfO/sub 2/ and SiO/sub 2/ are invariant with respect to operating frequency at least up to 20 GHz. In addition, the cutoff frequency f/sub t/ of the 100 nm CMOS transistor test structures with ZrO/sub 2/ gate dielectric was measured to be equal to 46 GHz for NMOS and 47 GHz for PMOS. The corresponding f/sub t/ values for HfO/sub 2/ were 45 GHz for NMOS and 35 GHz for PMOS. High-K film transistors with 80 nm physical gate lengths, 7 /spl mu/m gate width and layout optimized for high frequency testing were also fabricated. The NMOS devices achieved an f/sub t/ of 83 GHz and an f/sub max/ of 35 GHz, while the PMOS yielded 41 GHz and 25 GHz respectively. These results are very similar to those of CMOS transistors with SiO/sub 2/ gate dielectric at similar physical gate lengths and widths. These results are very encouraging and suggest that high-K gate dielectrics can be used for high-frequency logic applications.