Vacuum-insulated-gate field-effect transistor

A vacuum-insulated-gate field-effect transistor (VIGFET) is fabricated using a modified polysilicon-gate MOS process. The vacuum insulation is formed by first selectively etching the initial SiO₂ layer under the polysilicon gate in HF and then depositing LPCVD SiO₂ (LTO) to seal the evacuated cavity under the gate. Initial measurements of n-channel FET drain characteristics result in an effective value for the channel-electron mobility*gate capacitance product of k´= mu _nC´=21 mu A V^-2, comparable to that of conventional MOSFETs.