Power MOSFET Devices Integrated With Schottky Diode Simulation And Research

In recent years, due to the wide range of applications in the automotive electronics,computer peripherals, portable electronics, wireless communication, and other aspects, thelow-voltage power MOSFET (Metal Oxide Semiconductor Field Effect Transistor) has a rapiddevelopment. In medium-and Power MOSFET requires low switching losses, high switchingspeed, high reliability and simple manufacturing process. In order to meet these requirements,the low-voltage power MOSFET need to be developed to have a low on-resistance, lowparasitic capacitance, and high rugdness under inductively operating. In this paper, severalnew types of low-voltage power MOSFETs are proposed to improve these features.The main idea of this paper is to study power MOSFET devices integrate with Schottkydiode, design and optimize the device structure based on the model parameters of breakdownvoltage and on-resistance, analysis the process flow of the device, improve the deviceperformance, simulate and analyze the the device characteristics.The study emphase on the material properties and new device structure design, on thisbasis, complete the design of three high-performance power MOSFET devices with a fastreverse recovery, and promote the research and development of such devices.By using the rectifying effect of the metal-semiconductor contact, the relationshipbetween parasitic PN diode and device characteristics, the low barrier height and the majoritycarrier conductive characteristics of the schottky diode, through the adjustment of carrier inthe power MOSFET device, the performance of the power MOSFET device is optimized.First, a self-aligned dual-epi power VDMOSFET emmbed with schottky recitifier devicestructure is studied: SD-VDMOS (Self-aligned Dual-epi Vertical Double-diffused MOSFETintergrated with schottky rectifier), the schottky diode is integrated into the powerVDMOSFET device cell to save device area, accelerate the reverse recovery speed of thedecvice, the area of schottky junction can be flexibly controlled by the self-alignment process.The simulation results show that the reverse recovery characteristics of the SS-VDMOS aresignificantly superior to the tradional VDMOSFET transistor.Then a split gate enhanced power UMOSFET integrated with schottky element(sSGE-UMOS) is studied, the schottky rectifier is integrated into the cell of the split gateEnhanced devices (SGE-UMOS) to improve the reverse recovery speed of the device and lower forward voltage drop. By changing the width of the electrode of the schottky rectifier,the leakage current can be adjusted.Finally, an accumulation gate enhanced power U-shaped MOSFET integrated with aschottky rectifier (SAGE-UMOS) is studied, the schottky junction is integrated into each cell,the low leakage schottky metal and the N-base region contact to form a schottky diode, agood reverse recovery characteristics and low leakage current can be obtained in the case ofno P-type region in device. Further, by using the gate enhanced (GE) technology, thepolysilicon electrodes act as a deep trench gate electrode in the ON-state to improve theelectron current density of the device, the on-resistance is lower than the traditionalACCUFET devices. By changing the parameters of the the schottky rectifier electrode, theleakage current can be further decreased.