Characterization of the ultrathin vertical channel CMOS technology

In this paper, an ultrathin vertical channel (UTVC) CMOS with self-aligned asymmetric lightly doped drain is experimentally demonstrated. In the structure, the UTVC was obtained using solid phase epitaxy, and the midgap material, boron-doped poly-Si_0.5Ge_0.5, was used as the gate electrode to obtain symmetrical threshold voltages for both the NMOS and PMOS devices. Due to the ultrathin channel, the fabricated CMOS devices offer good immunity to short channel effects, and the typical subthreshold slopes of the 80 nm NMOS and PMOS are 102 mV/dec and 120 mV/dec, respectively. The fabricated CMOS inverters also show reasonable transfer characteristics. The UTVC CMOS technology provides a simple way to implement sub-100 nm devices for ULSI applications.