Study of direct-tunneling gate oxides for CMOS applications

Progress in MOS LSIs has continued for over 25 years through a process of MOSFET downsizing. Along with downsizing of MOSFETs, gate oxide thickness continues to be reduced. Recently proposed direct tunneling gate oxide MOSFETs show a good possibility for achieving extremely high drive currents (Momose et al., 1994, 1996, 1997; Lo et al., 1997; Timp et al., 1997). In this paper, it is shown that ultra-thin gate oxides beyond the tunneling limit can be applicable to MOSFETs and that extremely high DC and AC performances are realized. The hot-carrier reliability and oxide breakdown voltage of these MOSFETs are also compared with those of thicker oxide cases.