| 主权项 |
1. An insulated gate type switching device, comprising:
a first region being of a first conductivity type; a body region being of a second conductivity type and in contact with the first region; a second region being of the first conductivity type and separated from the first region by the body region; an insulating film being in contact with the first region, the body region and the second region; and a gate electrode facing the body region via the insulating film, wherein the body region comprises a first body region and a second body region, in a region being in contact with the insulating film, the first body region is in contact with the first region and separated from the second region by the second body region, in the region being in contact with the insulating film, the second body region is in contact with the second region and separated from the first region by the first body region, and the first body region has a theoretical threshold level Vth larger than that of the second body region, wherein
Vth=φMS−QB/Cox+2φFB, where φMS is a value obtained by subtracting a work function of the body region from a work function of the gate electrode, Cox is a capacitance per unit area between the body region and the gate electrode,
φFB=kT ln(NA/ni), k is a Boltzmann constant, T is a temperature of the body region, NA is a concentration of impurities in the body region, ni is a concentration of carriers in an intrinsic semiconductor made of a material of the body region, and wherein
QB=qNAxd, where q is an elementary charge of an electron,xd-(4ɛkTln(NAni)q2NA)12,and
∈ is a dielectric constant of the material of the insulating film. |
