Research On Electric Field Characteristics And Influencing Factors Of 3.3kV Power Chip Terminal

In recent years,with the development of power grid,high voltage and high power semiconductor devices,as the core devices of flexible equipment,require higher voltage grade and reliability of devices.As the core part of high voltage devices,high voltage power chip is becoming much more prominent.The withstanding voltage characteristics and influencing factors of the chip terminal are of great significance to the chip design.At present,the research on chip terminal mainly focuses on its breakdown voltage and reliability.Although the relevant technology has been developed in China,the influencing factors of terminal electric field have not been systematically studied.Therefore,it is urgent to study the manufacture process,terminal structure and the effect of interface charge on terminal electric field characteristics for the terminal design of domestic power chips.In this paper,the terminal structure of power chips with 3.3kV voltage level is taken as the research object,and the terminal structure of a variety of power chips with 3.3kV voltage level is analyzed and studied.The main contents of the work and research results include the following aspects:Firstly,by analyzing a domestic 3.3kV fast recovery diode chip,the terminal structure and the corresponding field-loop structure parameters are obtained by SEM.The theoretical model used in the process of TCAD software simulation was investigated.Based on the analytical data and the mainstream technology,the field-loop structure is simulated and modeled.When the interface charge concentration is 4 × 1011 cm-2,the voltage resistance of more than 3950 V is achieved,which meets the requirements of industrial design.The influence patterns and mechanism of the process factors on the breakdown voltage of the field-ring structure are revealed by analyzing the process factors with the simulation software.Secondly,in view of the shortcomings of the field-ring structure,a composite terminal structure of field-ring and field-plate for 3.3kV voltage IGBT chip was designed by simulation.When the interface charge concentration is 4 × 1011 cm-2,the voltage resistance of 4200V is achieved,which meets the needs of industrial design.The influence of the thickness of oxide layer and the length of the field plate on the breakdown voltage of the terminal structure is analyzed by TCAD software.In addition,the electric field distribution inside the terminal and the passivation layer is obtained by the co-simulation of the composite terminal structure and the passivation layer.Finally,aiming at the existing problems of the field-ring,composite of field-ring and field-plate terminal structure,a 3.3kV high voltage deep junction composite terminal structure was designed by using SIPOS,VLD and JTE technologies.The novel design structure can effectively restrain the impact of interface charge on the breakdown voltage of the VLD-JTE composite terminal structure.The main influence factors are analyzed by simulation software,and the influence law and mechanism of the breakdown voltage are revealed.