Study On Process Optimization And Reliability Improvement Of 650 Voltage VDMOS Power Device

With the development of science and technology,the application of ultra-large-scale integrated circuit technology makes a large number of new structure of the power semiconductor devices came into being,resulting in high-voltage high-current semiconductor quality changes occurred.VDMOS(Vertical Double-diffused Metal Oxide Semiconductor)power devices that are vertical conductive metal oxide semiconductor field effect transistor.VDMOS power device is a voltage regulator through the majority of carrier devices,the emergence of microelectronics technology and power electronics technology integration,as in the MOS integrated circuit technology developed on the basis of a new generation of power integrated power switching devices The VDMOS power devices have been widely used in inverter,electronic switches,electronic ballasts,motor speed,high-fidelity audio,automotive electronics and switching power supply and many other areas.This paper attempts to explore the effect of each process condition on the quality of the product passivation film from the four aspects of the reaction gas flow rate,the power of the RF power supply,the product surface temperature and the distance between the product and the nozzle.Factors unilaterally the most suitable production process parameters of the product.And then through the orthogonal experiment,the design of 4 factors 5 level of the sample,the impact of the various process parameters were compared,from which the most suitable for the production process parameters.Into the test,and finally concluded:1.The influence of the change of the reaction gas flow rate on the thickness and thickness deviation of the passive device is not obvious,but the influence of the refractive index and the internal stress is significant.2.The influence of RF power on the film thickness is significant.With the increase of RF power,the refractive index of the passivation film of the power device tends to decrease,and the absolute value of the stress in the passivation layer is increasing.Stress is getting bigger and bigger.3.When the surface temperature of the silicon wafer is between 350℃ and 400 ℃,the increase of the temperature of the silicon wafer contributes to the increase of the chemical vapor deposition rate.However,the refractive index of the passivation film increases with the increase of temperature,And the absolute value of the stress in the film layer is gradually becoming smaller,indicating that the defects within the film is getting smaller and smaller.4.As the distance between the wafer and the nozzle increases,the uniformity of the film thickness becomes worse,the thickness of the film at the center position is thicker,and the thickness of the film in the remaining positions decreases and the deviation of the film thickness gradually changes big.5.The optimum process parameters for the preparation of 4k? silicon nitride passivation film on the surface of the 650 V high voltage VDMOS power device are:the flow rate of the reaction gas is 38:14,the RF power is 350 W,the temperature of the silicon surface is 390℃,the silicon The distance between the slice and the nozzle is 340 mils.