The Design Of The Structure Of The Power VDMOS Device

VDMOS (Vertical Conduction Double-diffused Metal Oxide Semiconductor) is a widely used power semiconductor device in mobile communication, radar, switched-model power converters, automotive electronics, motor control; lamps ballasts, and so forth, because it offers better performance in input impedance, switching speed, safety operating area and thermal stability than bipolar power transistor.This article introduces the basic structure and the on-state characteristics of the VDMOS, including the main parameters and the characteristic curves. RF performance, capacitance characteristics and transconductance has been discussed in detail with ISE. Also we study the split gate VDMOS structure (SG) and the dummy-gated VDMOS (DG) structure. When the size of the device and the doping concentration are the same, the breakdown voltage of the split gate VDMOS and the dummy-gated VDMOS are 60V and 85V, 29% improving. The Parasitic Capacitance C_rss of the dummy-gated VDMOS are smaller compared with the split gate VDMOS' in the same F_ds. With the V_ds increasing, the C_rss of the dummy-gated VDMOS is nearly OF.The characteristics of the breakdown voltage are concluded and simulated with ISE, analyzing the influences of the surface charge, doping concentration of the substrate, junction depths and the thickness of epitaxial layer for the breakdown voltage. Two styles for improving breakdown voltage are proposed: field limiting rings (FLR) and field plate termination (FPT) structures, mainly discussing the field limiting rings structure in detail.By comprehending kinds of structure with excellent characteristic, a novel Dummy-gated with field limiting rings VDMOS device structure is studied when the excellent performance is realized. The electronics character of novel structure is proved with ISE. Compared to conventional VDMOS, the electronics character is more excellent.