Patent ID: 8362522
Filing Date: 2013-01-29
Classification: H01L

Abstract:
1. A semiconductor device comprising: a semiconductor substrate; a semiconductor film formed on the semiconductor substrate; a gate formed on an insulator film on the semiconductor film; and a pair of first impurity diffusion regions formed by doping the semiconductor film on both side of the gate with a first impurity; wherein the semiconductor film has a heterojunction structure formed by two layers of semiconductors of different types in which a second impurity exhibits different diffusion coefficients, and the second impurity is distributed with a higher concentration in one of the semiconductor layers than in the other of the semiconductor layers; wherein the second impurity is of a conductivity type opposite to a conductivity type of the first impurity; a second impurity diffusion region formed only one side of the gate by doping with the second impurity, and wherein the difference in the concentration of the second impurity between the semiconductor layers differs between a portion on a side of one of the first impurity diffusion regions and a portion on a side of the other one of the first-impurity diffusion regions.