Research On The Characteristics And Process Of VLD-JTE Composite Termination Structure

At present,the development direction of silicon power semiconductor device is large current,high voltage and lower loss.The termination structure directly affect the withstand voltage and the stability of the power device,which is the problem that the power device must be solved.In order to improve the blocking voltage of the power device,the termination structure needs to be further studied.The plane junction terminal has the advantages of being fully compatible with the source area,making the technology simple and the higher withstand voltage efficiency.Taking 4.5 kV GCT structure as an example,the VLD-JTE composite structure has been proposed in this paper,and the withstand voltage mechanism,blocking characteristics and production process of the terminal has been studied by software,the key process of aluminum selective doping was experimentally studied.There are main contents:Firstly,the relationship between the aluminum doping window and dose was investigated in theory,and the aluminum diffusion junction depth is derived with the doping dosage,window,temperature,and diffusion time,optimized the structure of the VLD lateral parameters.The results show that the VLD terminal surface with aluminum doping is low and the end is deep,which leads to the high peak electric field,makes the voltage decrease.Moreover,the positive charge of the layer can easily lead to the appearance of anti-type at the end of the VLD and reduce the reliability of the terminal.Secondly,in order to alleviate the surface electric field at the end of VLD and improve its reliability,A new VLD-JTE composite terminal structure is formed by adding a JTE zone at the end of VLD and setting a resistance zone on the outside of the main junction of the source zone.Studied the mechanism of the composite terminal withstand voltage and blocking features,optimized the JTE area concentration,junction depth and the length of the key parameters,analyzed the blocking characteristic of the composite structure under high and low temperature.Thirdly,the manufacture process of VLD-JTE composite termination is studied,and the key aluminum selective doping in VLD area is researched.Two schemes for forming VLD are designed,compared and analyzed the advantages and disadvantages of the two schemes.The process conditions were extracted by process simulation,and the aluminum doped process of masking film diffusion forming VLD terminal was tested.Results show that the GCT active region is compatible with the manufacturing of the terminal,but the VLD and JTE requires both the ion implantation process and subsequent high temperature push in technique,not significantly increases the production.The research results provide practical reference value for the development of high power semiconductor devices.