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,sp. Compared with the conventional SJ-LDMOSFET, the simulation results indicate that the BV of the
SSJ-LDMOSFET is increased from saturation voltage 121.7V to 644.9V; at the same time, the specific on-state resistance is decreased from 0.314Ω•cm² to
0.14Ω•cm² by virtue of 3D numerical simulations using ISE when the drift region length and the step number are taken as 48μm and 3, respectively.