A new recessed gate MOSFET structure with the graded source/drain

A gate recessed MOS (GR-MOS) structure with the selectively halo-doped channel by boron implantation carried out after graded (source/drain) (S/D) formation is proposed. The S/D is formed without n/sup +/ counter-doping to the channel doping. Initial characterization results of GR-MOSFETs having a 0.25 mu m channel length are presented in comparison with the conventional lightly doped drain (LDD)-MOSFETs. It was verified that the new concept gives improved device characteristics over the LDD structure for a wide range of bias conditions and channel lengths, and renders the device design window wider in deep submicron devices.