A novel super-junction lateral double-diffused metal-oxide-semiconductor field effect transistor with n-type step doping buffer layer

A novel super-junction lateral double-diffused metal-oxide semiconductor field effect transistor (SJ-LDMOSFET) with n-type step doping buffer layer is proposed. The step doping buffer layer almost completely eliminates the substrate-assisted depletion effect, modulates lateral electric field and achieves nearly uniform surface field. On the other hand, the buffer layer also provides another conductive path and reduces on-state resistance. In short, the proposed LDMOSFET improves trade-off performance between breakdown voltage (BV) and specific on-state resistance R-on,R-sp. Compared with the conventional SJ-LDMOSFET, the simulation results indicate that the BV of the SSJ-LDMOSFET is increased from saturation voltage 121.7 V to 644.9 V; at the same time, the specific on-state resistance is decreased from 0.314 Omega.cm(2) to 0.14 Omega.cm(2) by virtue of 3D numerical simulations using ISE when the drift region length and the step number are taken as 48 mu m and 3, respectively.