4H-SiC Power MOSFET Characteristics Research And Device Simulation

Silicon carbide (SiC) is one of the preferred semiconductor materials in the applications of high temperature, high-frequency, high-power and radiation resistant due to its excellent physical properties such as wide bandgap, high thermal conductivity and high critical breakdown field and high saturation electron drift velocity. The main studies and contributions of this paper are as follows.The effects of oxide layer thickness and the p-base doping concentration on threshold voltage have been simulated. Through the ISE-TCAD simulation, we found that the larger of oxide layer thickness and p-type base doping concentration, the greater of the threshold voltage. Therefore, in order to obtain a lower threshold voltage, the oxide layer thickness and the p-type base concentration must be reduced.The blocking characteristics of device have been studied. The doping concentration and thickness of the p-base region must be designed to be optimum values to prevent the peach-through from limiting the breakdown voltage.The reduction of specific on-resistance has been investigated. JFET resistance, accumulation resistance, channel resistance and drift region resistance is the most important components of on-resistance. In this thesis, the JFET resistance is effectively reduced by optimizing the concentration and width of JFET region. On the top of the drift region, the current spread layer is inserted, so that the current through the drift region is more uniform, leading to the reduction of the drift layer resistance.The concentration of JFET region, CSL and drift region have been optimized and with the approach of BFOM, the specific on-resistance of 1.54 mΩ·cm2 and the breakthrough voltage of 2100V are achieved.