Semiconductor device including well regions with different impurity densities
First Claim
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1. A semiconductor device comprising:
- a wide band gap semiconductor substrate that is of a first conductive type;
a drift layer that is of the first conductive type and configured with a wide band gap semiconductor and that is formed on a first main surface of the wide band gap semiconductor substrate;
a plurality of first well regions that are of a second conductive type and that are formed in a surface layer portion of the drift layer adjacent to each other at a predetermined interval;
a second well region that is formed adjacent to each of the first well regions and toward the semiconductor substrate, has a second conductive type impurity density lower than the first well regions, and has a constant width that is narrower than a width of the first well regions to form T-shaped well configurations;
a Schottky electrode that is formed on surfaces of the drift layer and the first well regions to form a Schottky connection with the drift layer; and
an ohmic electrode that is formed on a second main surface of the semiconductor substrate which is opposite to the first main surface,wherein at least some regions in the first well regions are not depleted when the semiconductor device is in an off-state.
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Abstract
In a JBS diode using a wide band gap semiconductor, the wide band gap semiconductor has a large built-in voltage, which sometimes causes difficulties for the pn diode portion to turn on, resulting in a problem that resistance to surge currents is not sufficiently ensured. In order to solve this problem, in the wide-band-gap JBS diode, a pn junction of the pn diode is formed away from the Schottky electrode, and well regions are formed so as to have a width narrowed at a portion away from the Schottky electrode.
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9 Claims
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1. A semiconductor device comprising:
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a wide band gap semiconductor substrate that is of a first conductive type; a drift layer that is of the first conductive type and configured with a wide band gap semiconductor and that is formed on a first main surface of the wide band gap semiconductor substrate; a plurality of first well regions that are of a second conductive type and that are formed in a surface layer portion of the drift layer adjacent to each other at a predetermined interval; a second well region that is formed adjacent to each of the first well regions and toward the semiconductor substrate, has a second conductive type impurity density lower than the first well regions, and has a constant width that is narrower than a width of the first well regions to form T-shaped well configurations; a Schottky electrode that is formed on surfaces of the drift layer and the first well regions to form a Schottky connection with the drift layer; and an ohmic electrode that is formed on a second main surface of the semiconductor substrate which is opposite to the first main surface, wherein at least some regions in the first well regions are not depleted when the semiconductor device is in an off-state. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
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Specification