High performance characteristics in trench dual-gate MOSFET (TDMOS)

It is experimentally shown that there is high current drivability and high reliability in a TDMOS, compared with those in the conventional trench transistor. The authors explain the high performance mechanism of TDMOS by using experimental data and two-dimensional device simulation. It has recently been observed that drain currents of the TDMOS are enhanced compared to those of a conventional trench transistor. The higher current in TDMOS is due to the increase of electron charge density in the inversion layer, resulting from reduced depletion layer charge caused by the gate bias. However, impact ionization of the TDMOS is much smaller than that of a single-gate trench transistor, resulting in a higher reliability in the TDMOS. Moreover, the substrate bias sensitivity of V_th is very low in the TDMOS structure. These effects are caused by the reduction in the depletion layer charge in the TDMOS, compared to that in the single-gate trench transistor