Simulation and Design of Vertical Power MOSFETs utilizing Silvaco’s ATLASTM

This paper reports on the design and simulation of 3C-SiC low-doped drain power MOSFETs,
including key parameters such as the avalanche impact ionization model and its relation to the
breakdown voltage, the doping dependence of the bulk mobility, and the relationship between the onresistance
and breakdown voltage. A set of MOSFETs with different blocking layer doping were
designed while scaling the parasitic JFET. A stepped doping profile is used to minimize localized
breakdown at the p-well/n-type drift layer interface. The characteristics of the MOSFETs were
obtained using a commercially available 2D simulation program. Comparisons made with a 1D
analytical model reveal good agreement of the on-state resistance, current-voltage characteristics,
sub-threshold slope and the overall validity of the simulation models developed, as long as the body
effect is properly included. Simulation results indicate that, for the chosen material parameters, a 600
V, 3C-SiC MOSFET with a thinned substrate, containing a drift-layer of 7 m and a blocking layer
doping density of 1x1016 cm-3, can have an on-state resistance of 0.8 mW-cm2.