Study On Technological Optimization Of High Voltage VDMOS Power Device

Among most power semi-conductors,power MOSFET,due to its capability for high input resistance and high power amplification,as well as better heat stability,is usually deployed for equipment in fields that requires under 10 KW of power,and under 1 KV of voltage.The VDMOS device skillfully combines the transverse surface insulation gate effect and the high-pressure structure,Pressure of drain source has been improved.This article focuses on the current technology problems of 600 V VDMOS products,optimizes the process.The main work of this paper is as follows.(1)The factors of volume concentration and gate oxygen thickness that cause the high threshold of VDMOS are analyzed.A process window screening scheme is proposed.The experimental results show that the adjustment of threshold voltage can be achieved at the same time that the breakdown voltage,the on state resistance and the leakage current of the source and drain are not changed.The design requirement of 3.45 V has been achieved(2)The influence of resistivity and thickness of epitaxial layer on breakdown voltage is analyzed.Without changing the layout design,by adjusting the resistivity and thickness of the epitaxial layer,the breakdown voltage and the on resistance are achieved.The experimental verification has been carried out.The result shows that the epitaxial layer resistivity of 17? ? cm and thickness of 51 ?mmeet the requirement of breakdown voltage and on resistance.(3)The influence of the stress and reflectivity of the silicon nitride on the reliability is clarified.The device reliability is improved by adjusting the passivation process of silicon nitride.(4)Based on the analysis of the existing process flow,the optimized process flow is obtained,the efficiency of the production line is improved and the cost is reduced.The test results show that the parameters such as threshold voltage,breakdown voltage,turn-on resistance,source drain current and other CP parameters of the devices meet all the requirements.The related technology and the development process platform in this paper have been used in mass production,and the yield has reached above 96%.This research has important practical significance...