Research On Back Process Of FS-IGBT Chip

Insulated gate bipolar transistor(IGBT)has the advantages of high blocking voltage,low forward drop,high switching speed,simple drive circuit and so on.It has been widely used in the fields of rail traffic,new energy and smart grid,and the voltage covers the application range of 600V?6.5kV.Because of the difficulty in making IGBT back process,the industrialization of high voltage IGBT is limited.Therefore,it is very significant for the research of FS-IGBT back process.Take the field-stop IGBT(FS-IGBT)of 3.3kV as an example.Firstly,the structure features of FS-IGBT and the designing method of back process are analyzed.Then the critical back process of FS-IGBT is simulated by Sentaurus-TCAD process,and experimental verification of the process is carried out.The principle of H+ injection to realize buried n FS layer doping is emphatically studied,and the analytical model of H+ injection is established with the help of SRIM and Matlab software,and the process conditions of H+ injection are extracted.Finally,the process intesgration is carried out,and the overall implementation scheme of FS-IGBT is obtained.The main research contents are as follows:Firstly,the structure characteristics and working principle of FS-IGBT are briefly described.The technological characteristics of the key areas on the back are analyzed.The realization method of the n FS layer and transparent collector is put forward in combination with the actual manufacturing process.Thus determining the overall process flow of the FS-IGBT.Secondly,the manufacturing process of FS-IGBT was simulated,and the influence of front process on the preparation of n FS layer was analyzed.According to the simulation results of single step process,the experimental plan of FS-IGBT single step process is determined and verified by one step process experiment.Finally,in order to improve the reverse withstand voltage of IGBT devices,the process implementation plan of H+ injection to achieve buried FS layer is studied.The principle of n FS layer doping by H+ injection was analyzed.The influence of annealing temperature on n FS layer surface concentration and the relationship between injection dose and doping concentration were analyzed.With the aid of SRIM and Matlab software,the analytical doping model of H+ injection was established,and the model parameters and process conditions were extracted.And then,through the process integration,the whole process implementation scheme of FS-1GBT chip with H+ injection and P+ injection to form n FS layer is obtained and compared.The research results in this paper can provide some reference for process design and development of high voltage FS-IGBT.