Manufacturing method of silicon carbide semiconductor device

摘要

A manufacturing method of a silicon carbide semiconductor device includes: forming a drift layer on a silicon carbide substrate; forming a base layer on or in a surface portion of the drift layer; forming a source region in a surface portion of the base layer; forming a trench to penetrate the base layer and to reach the drift layer; forming a gate electrode on a gate insulation film in the trench; forming a source electrode electrically connected to the source region and the base layer; and forming a drain electrode on a back surface of the substrate. The forming of the trench includes: flattening a substrate surface; and etching to form the trench after flattening.

主权项

1. A manufacturing method of a silicon carbide semiconductor device having a transistor with a trench gate structure having improved sidewall flatness, the method comprising:
forming a drift layer, which is made of silicon carbide and has a first conductive type with an impurity concentration lower than a substrate, on a substrate having the first conductive type or a second conductive type and made of silicon carbide; forming a base layer, which has the second conductive type and is made of silicon carbide, on or in a surface portion of the drift layer; after implanting a first conductive type impurity as an ion in a surface portion of the base layer, activating the ion-implanted first conductive type impurity and forming a source region made of silicon carbide and having the first conductive type with an impurity concentration higher than the drift layer; forming a trench having improved sidewall flatness by flattening a surface of the source region and directly etching a portion of the flattened surface of the source region, so as to penetrate the base layer and to reach the drift layer; forming a gate insulation film on an inner surface of the trench; forming a gate electrode on the gate insulation film in the trench; forming a source electrode electrically connected to the source region and the base layer; and forming a drain electrode on a back surface of the substrate.