Design And Simulation Of Anti-radiation High-Voltage VDMOS

As an revolution following the development of IC,Power semiconductor devices,is playing an important role in the control system of the whole scene.Now VDMOS occupies the dominant position due to its advantages of high output power,fast switching speed and process maturity,furthermore it has a good foreground.After years of hard work,we have achieved some results,but there is still a big gap with foreign countries.Applied to military or space field involved in national security,VDMOS need to have the irradiation resistance,which ensure that it will not fail in the strong radiation condition so that the spacecraft can function properly.In this area,China is facing a serious blockade both in product and technology,which has resulted in a two-decade gap between China and foreign countries.Design anti-irradiation high-voltage VDMOS devices independently based on the domestic process line,and improve the localization rate is of great significance.The paper introduces the development status of irradiation-resistant VDMOS domestic and international,and points out the difficult situation that China is facing.By making a detailed introduction to the basic structure and working principle of the VDMOS,analyzing its parameters,a good theoretical foundation for design of high-voltage anti-irradiation N-channel depletion VDMOS is laid.Cooperating with foundry,we design a anti-radiation peocess for depletion VDMOS based on ordinary commercial process.The backgate process adjusted from a non-self-aligning process,which remove the surface oxide layer,and re-deposit field oxygen after all bulk silicon processes,then etch out the active zone and regrow the high quality oxide layer at1000°C for gate oxygen.No more high-temperature processes after gate oxidation.The elimination and monitoring of movable ions are optimized for several process modules,such as polysilicon,ILD isolation layer,and passivation layer,which have a strong influence on the total dose effect,to realizing the need for irradiation resistance The device pass the simulation test of total dose radiation effect at 100KRad(Si),for the threshold voltage does not exceed the qualifying range.Then we complete the device design by simulation.So firstly the ideological approach to simulation is introduced,consist of the setting of the mesh,the selection of the physical model,and the various simulation methods of parameters.According to the process,thickness and doping concentration of epitaxial layer,polysilicon gate width,reverse injection dose,and Pwell parameters are adjusted with Sentausus,The best value is selected by comparing the simulation results of breakdown voltage,threshold voltage and characteristic on-resistance together.A cell with 725V of breakdown voltage,-1.4 of threshold voltage and 11.9?·mm~2 of specific on-resistance is formed.Then we devise a three-ring field limiting ring structure with 737.2V of breakdown voltage,which has a good distribution of potential and electric field.At last the layouts are designed and delivered to foundry for prototyping.In this paper,we propose a process,develop a 600 V anti-total dose radiation effect N-channel depletion VDMOS.and share the thinking path which provides a platform of experience and technology for subsequent improvement.The simulation results show that the designed VDMOS meets with the requirements.It has certain significance for breaking the international monopoly and achieving self-sufficiency in China as soon as possible.