Radio-frequency performance of a sub-100 nm metal-oxide field-effect transistor with high-k gate dielectric

Radio-frequency (rf) performances of a sub-100 nm MOSFET with two different gate dielectrics have been characterized. A 59 nm gate-length field-effect transistor (FET) with a SiON gate dielectric exhibited a cut-off frequency (f_T) and a maximum oscillation frequency (f_max) of 178 and 127 GHz, respectively. However, an FET with a HfSiON gate dielectric exhibited 148 and 122 GHz, respectively. The reduction in f_T has been found to be attributed to the degradation in the mobility and not to the dielectric relaxation of the HfSiON film. It has been confirmed that the high dielectric constant of HfSiON films can be utilized for future rf CMOS circuits at least up to 40 GHz.