Method for manufacturing semiconductor substrate of large-power device

A method for manufacturing the semiconductor substrate of the large-power device adopts the processing procedures of bonding the floating zone silicon wafer and a heavily CZ-doped silicon wafer to form the semiconductor substrate, comprising:

• Step 1:
• process the required floating zone silicon wafer, which comprises the procedures of:
• Providing a silicon substrate;
• Performing hydrogen ion (H+) injection and annealing on the silicon substrate to form a heavily H-doped layer in the silicon wafer;
• Performing phosphorous or boron ion injection to form a first doping type of the buffer layer between the heavily H-doped layer and the silicon wafer surface;
• If the first doping type uses phosphorous ions, performing boron ion injection to form a second doping type of a heavily doped region on the silicon wafer surface and on the upper part of the first doping type of the buffer layer, wherein the depth is smaller than that of the first doping type of the buffer layer;
• if the first doping type uses boron ions, performing the phosphorous ion injection to form a second doping type of a heavily doped region on the silicon wafer surface and on the upper part of the first doping type of the buffer layer, wherein the depth is smaller than that of the first doping type of the buffer layer;
• Forming a first insulation film on the silicon wafer surface,
• Forming a first photoresist layer on the first insulation film;
• Performing masking, exposing and etching and keeping a circle of first insulation film on the edge of the silicon wafer;
• Removing the first photoresist layer;
• Forming a first diffusion-impervious layer on the silicon wafer surface and on the first insulation film;
• Step 2:
• process the required heavily CZ-doped silicon wafer, which comprises the procedures of:
• Providing a heavily CZ-doped silicon substrate which has the same doping type as the first doping type in the first step;
• Forming a diffusion-impervious layer on the surface of the CZ silicon substrate;
• Forming a metal or metal oxide layer on the surface of the diffusion-impervious layer formed in the previous step;
• Forming a first photoresist layer on the metal or metal oxide layer formed in the previous step;
• Optically etching the first photoresist layer formed in the previous step and the etching to remove a circle of diffusion-impervious layer and a circle of metal or metal oxide on the edge of the CZ silicon wafer;
• Removing the first photoresist layer;
• Step 3:
• bond the diffusion-impervious layer of the floating zone silicon wafer formed in the first step with the metal or metal oxide on the heavily CZ-doped silicon wafer formed in the second step and then remove the floating zone silicon wafer part of the H-layer or above the H-layer in the floating zone silicon wafer.