Simulation And Fabrication Of 4H-SiC Schottky Barrier Diodes And Junction Barrier Schottky Diodes

Silicon Carbide(SiC)has many advantages,such as wide band gap,high c ritical field strength,high thermal conductivity and high electron saturation speed.So it is suitable for high temperature,high pressure and high power applications.As one of the important power devices,diodes need to have the characteristics of small on-resistance,fast switching speed,and high blocking voltage.Therefore,Schottky barrier diode(SBD)and junction barrier Schottky(JBS)diodes have great application potential in power electronics.The study of SiC diodes starts late in China,and we still need to catch up in processes and design.In view of this situation,this paper mainly studies the simulation and fabrication of SiC SBD and JBS diodes:(1)With the help of Sentaurus TCAD,we simulated the field plate(FP)terminal of SiC SBD,and studied the effects of field plate length and oxide layer thickness on the breakdown voltage.Meanwhile,we extracted the electric field distribution of the device for the analysis results.(2)The key processes,including Schottky contact,ohmic contact,etching a nd photolith were studied.In order to solve the problem that the etching rate of ICP cannot be accurately controlled,we introduced a new process.We deposited metal first,then grew Si O ₂ and etched last.Finally,the SiC SBD with field pla te terminal was made and tested.The results showed that the property of Schottky contact was great.The ideal factor was close to 1,the barrier height was 1.5 e V and the maximum breakdown voltage was 643 V.(3)The cell structure of JBS diodes was optimized,including the spacing,width,doping concentration and depth of P⁺region.Then the field limiting ring(FLR)terminal was optimized,including the spacing and the number of FLR.Finally,the process of ion implantation and high temperature annealing were introduced and simulated by Trim.The energy and dose required by ion implantation were obtained.(4)Combining the experience of making SBD,ion implantation and high temperature anneal,the SiC JBS diodes were fabricated.The test results showed that the maximum breakdown voltage was 1045 V,which was 78% higher than SBD.