Semiconductor device and method of manufacturing the same

摘要

Provided is a technique of securing reliability of a gate insulating film, as much as in a Si power MOSFET, in a semiconductor device in which a semiconductor material having a larger band gap than silicon is used, and which is typified by, for example, an SiC power MOSFET. In order to achieve this object, in the in the SiC power MOSFET, the gate electrode GE is formed in contact with the gate insulating film GOX, and is formed of the polycrystalline silicon film PF1 having the thickness equal to or smaller than 200 nm, and the polycrystalline silicon film PF2 formed in contact with the polycrystalline silicon film PF1, and having any thickness.

主权项

1. A semiconductor device comprising:
(a) a substrate of a first conductivity type which has a first main surface and a second main surface opposite to the first main surface, and is made of a semiconductor material having a larger band gap than silicon; (b) a drift layer of the first conductivity type formed on the first main surface of the substrate; (c) a well region of a second conductivity type which has a first depth from a top surface of the drift layer, and is obtained by introducing a first impurity of the second conductivity type different from the first conductivity type into the drift layer; (d) a source region of the first conductivity type which has a second depth from the top surface of the drift layer, and is disposed in the well region being separated from an end portion of the well region, and into which a second impurity of the first conductivity type is introduced; (e) a gate insulating film which is in contact with, at least, the well region between the drift layer and the source region; (f) a gate electrode which is in contact with the gate insulating film; and (g) a drain region of the first conductivity type formed on the second main surface side of the substrate, wherein the gate electrode includes:
(f1) a damage suppressing layer which is in contact with the gate insulating film and suppresses damage on the gate insulating film; and(f2) a resistance reducing layer which is formed on the damage suppressing layer and reduces a gate electrode resistance more than a case without providing the resistance reducing layer, and the damage suppressing layer is formed using a second material different from a first material for forming the drift layer and the well region, wherein the first material and the second material have different thermal expansion rates, and wherein a thickness of the damage suppressing layer is equal to or smaller than 200 nm.