Design And Study Of RF VDMOS Device Structure

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, lamp ballasts, and so forth, because it offers better performance in input impedance, switching speed, safety operating area and thermal stability than bipolar power transistor. Nowadays more than 90 percents of VDMOS products in China need to be imported. Therefore, it is very important to study and model the physical and electrical characteristic of VDMOS.The structure of VDMOS had been established. The relations of the breakdown voltage to substrate concentration and channel concentration had been discussed in detail with ISE. The cause of quasi-saturation effect has been investigated and analysed by software. An improvement is proposed and simulated. After the simulations on the parameters of VDMOS, the principle of design VDMOS is received.The relationship between between gate-drain capacitance (Cgd) and drain-source voltage (Vds) is concluded. The influence of thickness and length of gate oxide ,drift concentration and channel concentration on gate-drain capacitance (Cgd) is analysed. The improvement of DG-VDMOS on capacitance is proved.The structure of superjunction is introduced and analysed. Superjunction can improve breakdown voltage clearly. The operational principle of superjunction device based on superjunction theory is discussed, along with its shortcomings. The structure of PFVDMOS is available in process and can promote breakdown voltage evidently.By comprehending kinds of structure with excellent characteristic, a novel PFDG-VDMOS device structure is proposed 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.