Device Fabrication And Static/Dynamic Characteristic Investigation Of High-voltage 4H-SiC PiN Diodes

The third generation semiconductor Silicon Carbine(SiC)has drawn a lot of attention for it has many unique features such as wide-band-gap,high thermal conductivity,high critical electric field and high electron saturated velocity.As the maturity level of Silicon(Si)technology,it is hard to make a breakthrough in the power semiconductor industry.Devices made of SiC have a higher blocking voltage,higher power density,higher switching speed and other advantages over ones made of Si.Studies of SiC are still at the primary stage.This thesis is aiming at the high-voltage 4H-SiC PiN diodes presenting the design,optimization,manufacturing and testing processes.For the purpose of providing a reference for the research 4H-SiC PiN diodes of the nation.Firstly,design and optimization of the 4500 V high-voltage 4H-SiC PiN diodes were done by using Silvaco the semiconductor numerical simulation platform.The thickness of the drift layer of the cell is 40?m,which can provide a breakdown voltage of 5600 V,the cell forward voltage is 3.5V when the forward current density is at 100A/cm~2.A Mesa with Junction Termination Extension(JTE)termination structure is used in the diodes and giving a 96% termination efficiency.The dynamic characteristic of reverse recovery of 4H-Si C PiN diodes were studied and simulated.Then the deep levels in SiC were studied as well as their effects on the PiN diodes.Secondly,the critical processes of manufactory of the high-voltage 4H-SiC PiN diodes were studied,designed and optimized.The mesa structure etching is studied and developed via ICP etching technology.The ohmic contact processes of SiC were studied and optimized.The specific contact resistance of 1e-6?·cm~2 for N-type Si C ohmic contact process and 5e-5?·cm~2 for P-type SiC ohmic contact process were achieved.Finally,the 4500 V high-voltage 4H-SiC PiN diodes were experimentally taped out and tested.Resulting a 4V forward voltage when the forward current is at 11 A and the turn-on voltage is 3.4V while the current density is 100A/cm~2.The reverse blocking voltages reach an average of 4700 V.