Multigate MOSFET in a Bulk Technology by Integrating Polysilicon-Filled Trenches

We present a new device structure consisting of a MOSFET with two additional lateral trench gates. This multigate MOSFET can be implemented and fabricated in a standard bulk CMOS technology with a few extra process steps for integrating polysilicon-filled trenches. This device is investigated for operations as lateral-gate and surface-gate transistors. Lateral-gate current-voltage characteristics exhibit multiple-threshold-voltage behavior, which may be due to nonhomogeneous doping distributions. Surface-gate characteristics are similar to those of a conventional MOSFET except that the threshold voltage is adjustable to some degree by lateral-gate bias. In effect, due to edge field effects at the corner regions between surface and lateral gates, the channel width under one gate may be modulated by its adjacent gate bias.