The Research On The SPICE Model For Power VDMOS

Because of the high input impedance, low driving power and fast switching speed, vertical double diffused metal oxide semiconductor (VDMOS) transistor has been widely used in the field of the power integrated circuits. SPICE model is the circuit device model based on the text description and it is the bridge linking the device process and the circuit design. However, there is not widely accepted VDMOS SPICE model at present. Thereby, the research on VDMOS SPICE modeling is of great significance.In the thesis, a complete VDMOS SPICE model is developed which includes the DC characteristic model based on the surface potential and the AC characteristic model based on the charges. The VDMOS device is divided into the channel region the accumulation resistance area, the parasitic Junction Field-Effect Transistor (JFET) area, N- epitaxial layer area and N+substrate area when building the DC characteristic model, the channel region model and the accumulation resistance model are built based on the surface potential, the parasitic JFET model is set up by analyzing the depletion and the pinch-off effects of the parasitic JFET, the N-epitaxial layer model and the N+ substrate model are built by considering of the current paths in the corresponding areas. In addition, the AC characteristic models of VDMOS device are presented, which include Cgd model, Cgs model and Cds model. Furthermore, the Verilog-A description language is used to describe the VDMOS SPICE model and the measurement platform is used to get the DC characteristic data and the AC characteristic data. At last, the entire model parameters extraction process is carried out based on the measured data and the presented model, and then all the verification results of simulation data are given.The presented SPICE model of VDMOS device has clear physical significance with the fast simulation speed and the high convergence. The root mean square error between the simulation curve based on the DC characteristic model and the measurement data is less than 5% and the root mean square error between the simulation curve based on the AC characteristic model and the measurement data is less than 7%. The presented models can be directly applied into the SPICE simulation tools, which meet the expected goals.