Fabrication and characterization of vertical-type double-gate metal-oxide-semiconductor field-effect transistor with ultrathin Si channel and self-aligned source and drain

A fabrication technique for a vertical double-gate metal-oxide-semiconductor field-effect transistor (DG MOSFET) with a standing-up ultrathin channel (UTC) and self-aligned source and drain (S/D) is proposed. A $20\mathrm{nm}$ thick vertical UTC with low channel thickness fluctuation was formed on a (110)-oriented Si substrate using orientation-dependent wet etching. The top and bottom S/D were self-aligned to the DGs by using a combination of ion implantation and solid-phase diffusion. The fabricated vertical DG MOSFETs revealed that the channel thickness less influences the threshold voltage. Furthermore, a low sub-threshold slope of $68.8\mathrm{mV}$ /decade was achieved with a channel thickness of $20\mathrm{nm}$ .