METHOD FOR MANUFACTURING SILICON CARBIDE SEMICONDUCTOR DEVICE

摘要

A method for manufacturing a SiC semiconductor device includes: forming recesses to be separated from each other on a cross section in parallel to a surface of the substrate by partially removing a top portion of the drift layer with etching using a mask after arranging the mask on a front surface of a drift layer; forming electric field relaxation layers having the second conductivity type to be separated from each other on the cross section by ion-implanting a second conductivity type impurity on a bottom of each recess using the mask; and forming a channel layer by forming a second conductivity type layer on the front surface of the drift layer including a front surface of each electric field relaxation layer in a respective recess.

主权项

1. A method for manufacturing a silicon carbide semiconductor device comprising:
forming, on a substrate made of silicon carbide and having a first conductivity type or a second conductivity type, a drift layer made of silicon carbide and having the first conductivity type with an impurity concentration lower than the substrate; forming a plurality of recesses to be separated from each other on a cross section in parallel to a surface of the substrate by partially removing a top portion of the drift layer with etching using a mask after arranging the mask on a front surface of the drift layer; forming a plurality of electric field relaxation layers having the second conductivity type to be separated from each other on the cross section by ion-implanting a second conductivity type impurity on a bottom of each recess using the mask; forming a channel layer by forming a second conductivity type layer on the front surface of the drift layer including a front surface of each electric field relaxation layer in a respective recess, the channel layer being electrically connected to each electric field relaxation layer; forming a source region made of silicon carbide and having the first conductivity type with a concentration higher than the drift layer by ion-implanting a first conductivity type impurity on a top portion of the channel layer; forming a trench between the plurality of electric field relaxation layers, the trench penetrating from a front surface of the source region through the channel layer to reach the drift layer and having a depth shallower than the electric field relaxation layers; forming a gate insulating film on an inner surface of the trench; forming a gate electrode on the gate insulating film in the trench; forming a source electrode electrically connected to the source region and the channel layer; and forming a drain electrode on a rear surface of the substrate.