High Voltage Power Device Terminal Design Based On SIPOS Material

High-voltage power electronic devices have been widely used in today's society and occupy an irreplaceable position.In recent years,with the efforts of scientific researchers and in-depth research,there have been many different types of terminal technology and each terminal has its own advantages.The addition of SIPOS materials is a new improvement of terminal passivation technology and field plate technology.This paper mainly studies the traditional Field Limiting Ring terminal and VLD terminal as well as the new terminal with SIPOS material added on the basis of the traditional terminal,and TCAD Silvaco simulation software is used to analyze and compare the terminal technology.The main research contents include the following aspects:Firstly,this paper introduces the research significance of this topic,the terminal technology,and analyzes the SIPOS materials and their characteristics.This paper expounds the development and application of terminal technology as well as the principle and effect of SIPOS material in terminal application.Furthermore,the mechanism of terminal withstand voltage and the principle of junction breakdown are explained in detail.The impact ionization coefficient and avalanche multiplication effect are analyzed.The potential and depletion layer distribution are considered.This paper analyzes the reasons why four terminals(Field Plate,Field Limiting Ring,Junction Termination Expansion and Bevel Edge)increase the breakdown voltage of devices from the perspectives of electric field distribution and depletion layer expansion.The influence of adding SIPOS material into the terminal on the device's voltage withstand is analyzed,that is,the introduced SIPOS layer can be used as the passivation layer,and the effect of optimizing the device's electric field peak and expanding the main junction's depletion layer can be achieved by changing the material resistivity,so as to improve the breakdown voltage of the device.Based on IGBT device has been through the simulation software TCAD Silvaco cellular automata model of terminal first design a traditional field limiting ring structure of terminal.Then,a SIPOS layer is added on the basis of this traditional structure to design a new type of field limiting ring terminal.The breakdown characteristics of the traditional terminal and the new terminal is compared,and has simulated different characteristics.Next,a VLD terminal with the same cell as the field limiting ring terminal is designed and SIPOS material is added on the basis of the traditional VLD structure.When designing the VLD terminal,the simulation verifies the VLD morphology under three different masks and selects the optimal scheme,and simulates the influence of the process condition deviation on the terminal characteristics of the new VLD terminal.It is found that the breakdown characteristics of the terminal are influenced by the injected energy,injected dose,drive time and drive temperature,etc.The variation of terminal breakdown voltage with temperature is simulated and the reason is analyzed.Finally,the difference of breakdown characteristics between the two new terminals and the traditional terminals is analyzed,and the simulation verifies that the change of the new type of field limiting ring terminal and the new type of VLD terminal with the change of process parameters and analyzes the reasons.With the change of process conditions,such as injection energy,injection dose,drive time and drive temperature,the morphology of the VLD structure,such as the depth of the junction and the maximum concentration,will change,thus affecting the breakdown voltage of the terminal.The size and process tolerances of VLD terminal and FLR terminal are compared,and the advantages of the two terminals are analyzed.