Process Optimization For High Voltage VDMOS Threshold Voltage

Power semiconductor device is one of very important components in the power electronics field. As a typical of semiconductor power devices, VDMOS is the mainstream of the field of power electronic devices now.This paper summarizes the history and current research situation of development of VDMOS inbroad and out of abroad and some problems about VDMOS in real cases in the factory production. Put forward the value of the topic and research. The principle of VDMOS and the wafer level testing of feature parameters are discussed, the basic structure and the production process of VDMOS devices is introduced in detail. Then, this paper focuses on the analysis of the influences of various process factors to power VDMOSFET threshold voltage. For these factors, first, the specific general process principles are discussed, then the main equipments used in design of experimental are introduced, and the process parameters and the optimum parameters areprocess control parameters are given according to the experimental results.The influences of main process of threshold voltage of VDMOS include: thermal oxidation of gate oxide layer, polysilicon gate dry etching process, body doping ion implantation, photo resist thickness of deep boday lithography. In addition, the source dopping ion implantation energy, the inter layer dielectric thickness on the high voltage VDMOS have a certain effect. The process optimized parameters or suggestions of process control for Gate oxide thickness, polysilicon gate sidewall angle, body doping ion implantation dosage, deep body critical dimension and alignment tolerance are given.The high voltage VDMOS with optimized process reaches the expected VTH performance, the mean while, the avalanche breakdown and reliability performance of VDMOS are also improved. The optimized processes are used for mass production of 600 volts to 1000 Volts VDMOS. Lots of VDMOS use only one robust process condition, which is very good for productivity improvement. This research has significance and practical value to the development and manufacturing of similar of VDMOS devices.