Patent ID: 7622741
Filing Date: 2009-11-24
Classification: H01L

Abstract:
1. A semiconductor device of a double diffused MOS structure employing a silicon carbide semiconductor substrate, the device comprising: a silicon carbide semiconductor epitaxial layer provided on a surface of the silicon carbide semiconductor substrate and having a first conductivity which is the same conductivity as the silicon carbide semiconductor substrate; an impurity region formed by doping a surface portion of the silicon carbide semiconductor epitaxial layer with an impurity of a second conductivity, the impurity region having a profile such that a near surface thereof has a relatively low second-conductivity impurity concentration and a deep portion thereof has a relatively high second-conductivity impurity concentration, wherein a second-conductivity impurity concentration in an outermost surface portion of the impurity region is controlled to be lower than a first-conductivity impurity concentration in the silicon carbide semiconductor epitaxial layer; a further impurity region by doping a surface portion of the impurity region of the second conductivity with an impurity of the first conductivity; and a channel region having the first conductivity formed in the outmost surface portion between the epitaxial layer and the further impurity region of the first conductivity, an impurity concentration of the first conductivity in the channel region is lower than the second-conductivity impurity concentration in the deep portion of the impurity region of the second conductivity.