Doping method suitable for silicon carbide semiconductor device

Abstract

The invention relates to a doping method suitable for a silicon carbide semiconductor device. According to the invention, a second-conductive-type doped region and a first-conductive-type doped region are prepared in a silicon carbide wafer; the second-conductive-type doped region comprises a second-conductive-type deep-doped region formed by ion implantation and a second-conductive-type surface-doped region formed by laser doping; the doping depth of the second-conductive-type deep-doped region in the silicon carbide wafer is larger than the doped-region depth of the second-conductive-type surface-doped region in the silicon carbide wafer and the doping depth of the first-conductive-type doped region in the silicon carbide wafer; the second-conduction-type surface-doped region is located above the second-conductive-type deep-doped region; and the first-conductive-type surface-doped region is adjacent to the first-conductive-type deep-doped region. According to the invention, ion implantation times can be reduced, reduction of surface concentration is avoided, box-type impurity distribution after doping is effectively realized, process difficulty is reduced, and process precision is improved.

Description

technical field [0001] The invention relates to a doping method, in particular to a doping method suitable for silicon carbide semiconductor devices. Background technique [0002] Ion implantation is a key process for all SiC (silicon carbide) devices. Due to the extremely low diffusion constant of impurities in SiC, it cannot be doped using a diffusion process like silicon wafers, and in the activation annealing of implantation, the diffusion of most impurities after implantation is so small that it can be ignored. Therefore, in order to realize the box distribution of ion implantation, multi-stage implantation method must be adopted at present. [0003] At present, the ion implantation of the N-type region mostly uses N and P ion implantation, and the ion implantation of the P-type region mostly uses Al ion implantation. Since the extraction of the device electrode requires the combination of the heavily doped surface and the metal to form an ohmic contact, the latter st...

AI Technical Summary

Problems solved by technology

However, since the laser can only achieve surface heating, and the diffusion constant of Al in 4H-SiC is extremely low, the laser doping depth is only about 200nm

In the current SiC power devices, the P-type doping depth needs to be greater than 500nm, therefore, the laser doping process is difficult to meet the doping requirements in SiC power devices

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