Silicon carbide semiconductor device and method for manufacturing the same
First Claim
1. A method for manufacturing a silicon carbide semiconductor device comprising the steps of:
- preparing a semiconductor substrate including a silicon carbide substrate and first to third semiconductor layers, wherein the first semiconductor layer made of silicon carbide and having the first conductive type and an impurity concentration lower than that of the silicon carbide substrate, the second semiconductor layer made of silicon carbide and having the second conductive type, and the third semiconductor layer made of silicon carbide and having the first conductive type are formed on the silicon carbide substrate having a first conductive type or a second conductive type in this order;
forming a trench in a cell region of the semiconductor substrate so that the trench penetrates the second and the third semiconductor layers and reaches the first semiconductor layer;
forming a fourth semiconductor layer having the first conductive type in the trench by an epitaxial growth method;
forming an oxide film in the trench in such a manner that a part of the fourth semiconductor layer disposed on a sidewall of the trench is thermally oxidized, wherein the oxide film includes a part for functioning as a gate oxide film;
forming a gate electrode on a surface of the oxide film in the trench;
forming a first electrode electrically connecting to the third semiconductor layer; and
forming a second electrode electrically connecting to the silicon carbide substrate.
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Accused Products
Abstract
A method for manufacturing a silicon carbide semiconductor device includes the steps of: preparing a semiconductor substrate including a silicon carbide substrate and first to third semiconductor layers; forming a trench in a cell region of the semiconductor substrate; forming a fourth semiconductor layer in the trench; forming an oxide film in the trench such that a part of the fourth semiconductor layer on a sidewall of the trench is thermally oxidized; forming a gate electrode on the oxide film in the trench; forming a first electrode electrically connecting to the third semiconductor layer; and forming a first electrode electrically connecting to the silicon carbide substrate.
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Citations
16 Claims
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1. A method for manufacturing a silicon carbide semiconductor device comprising the steps of:
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preparing a semiconductor substrate including a silicon carbide substrate and first to third semiconductor layers, wherein the first semiconductor layer made of silicon carbide and having the first conductive type and an impurity concentration lower than that of the silicon carbide substrate, the second semiconductor layer made of silicon carbide and having the second conductive type, and the third semiconductor layer made of silicon carbide and having the first conductive type are formed on the silicon carbide substrate having a first conductive type or a second conductive type in this order; forming a trench in a cell region of the semiconductor substrate so that the trench penetrates the second and the third semiconductor layers and reaches the first semiconductor layer; forming a fourth semiconductor layer having the first conductive type in the trench by an epitaxial growth method; forming an oxide film in the trench in such a manner that a part of the fourth semiconductor layer disposed on a sidewall of the trench is thermally oxidized, wherein the oxide film includes a part for functioning as a gate oxide film; forming a gate electrode on a surface of the oxide film in the trench; forming a first electrode electrically connecting to the third semiconductor layer; and forming a second electrode electrically connecting to the silicon carbide substrate. - View Dependent Claims (2, 3, 4, 5, 6, 7)
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8. A method for manufacturing a silicon carbide semiconductor device comprising the steps of:
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preparing a semiconductor substrate including a silicon carbide substrate and first to third semiconductor layers, wherein the first semiconductor layer made of silicon carbide and having the first conductive type and an impurity concentration lower than that of the silicon carbide substrate, the second semiconductor layer made of silicon carbide and having the second conductive type, and the third semiconductor layer made of silicon carbide and having the first conductive type are formed on the silicon carbide substrate having a first conductive type or a second conductive type in this order; forming a trench in a cell region of the semiconductor substrate so that the trench penetrates the second and the third semiconductor layers and reaches the first semiconductor layer; forming a fourth semiconductor layer having the first conductive type in the trench by an epitaxial growth method, wherein a part of the fourth semiconductor layer disposed on a sidewall of the trench has a thickness substantially equal to a thickness of a part of the fourth semiconductor layer disposed on a bottom of the trench; forming a low resistance layer in such a manner that a first conductive type impurity is introduced from an upper side of the semiconductor substrate by an ion implantation method so that the first conductive type impurity is doped through the fourth semiconductor layer on the bottom of the trench; forming an oxide film in the trench in such a manner that a part of the fourth semiconductor layer disposed on the sidewall of the trench is thermally oxidized, wherein the oxide film includes a part for functioning as a gate oxide film; forming a gate electrode on a surface of the oxide film in the trench; forming a first electrode electrically connecting to the third semiconductor layer; and forming a second electrode electrically connecting to the silicon carbide substrate. - View Dependent Claims (9, 10, 11, 12)
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13. A method for manufacturing a silicon carbide semiconductor device comprising the steps of:
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preparing a semiconductor substrate including a silicon carbide substrate and first to third semiconductor layers, wherein the first semiconductor layer made of silicon carbide and having the first conductive type and an impurity concentration lower than that of the silicon carbide substrate, the second semiconductor layer made of silicon carbide and having the second conductive type, and the third semiconductor layer made of silicon carbide and having the first conductive type are formed on the silicon carbide substrate having a first conductive type or a second conductive type in this order; forming a trench in a cell region of the semiconductor substrate so that the trench penetrates the second and the third semiconductor layers and reaches the first semiconductor layer; forming an ion implantation region on an inner wall including a sidewall of the trench in such a manner that a first conductive type impurity, a second conductive type impurity, a silicon atom or a carbon atom is implanted slantwise on the semiconductor substrate; forming an oxide film in the trench in such a manner that a part of the ion implantation region disposed on the sidewall of the trench is thermally oxidized, wherein the oxide film includes a part for functioning as a gate oxide film; forming a gate electrode on a surface of the oxide film in the trench; forming a first electrode electrically connecting to the third semiconductor layer; and forming a second electrode electrically connecting to the silicon carbide substrate. - View Dependent Claims (14, 15, 16)
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Specification