Semiconductor device having high breakdown voltage without increased on resistance
First Claim
1. A semiconductor device comprising:
- a semiconductor substrate having a top surface and a back surface, wherein the back surface is opposite to the top surface;
a source region of a first conduction type, which extends in the substrate perpendicularly from the top surface;
a base region of a second conduction type, which extends perpendicularly from the top surface, wherein the base region has a first surface and a second surface, the second surface being opposite to the first surface, wherein the first surface of the base region contacts the source region;
a drift region of the first conduction type, wherein the drift region has an impurity concentration lower than that of the source region and extends perpendicularly from the top surface and contacts the second surface of the base region;
a drain region extending perpendicularly from the top surface in the drift region;
a gate insulating film formed on a surface that defines a trench, wherein the gate insulating film extends perpendicularly from the top surface and extends in a lateral direction from the source region to the drift region through the base region; and
a gate electrode formed on a surface of the gate insulating film such that, when a voltage is applied to the gate electrode, a channel region is generated in the vicinity of a surface of the base region adjacent to the trench, wherein the flow of the channel occurs in the lateral direction.
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Abstract
A first trench is formed in a surface of an n+-type semiconductor substrate that forms a source region. A p-type base region, an n−-type drift region, and an n+-type drain region are deposited in this order in the first trench using epitaxial growth. A second trench extending from the source region to the drift region through the base region is formed in the surface. A gate insulating film and a gate electrode are formed on a surface defining the second trench. The n+-type drain region has a location where growing surfaces come together in epitaxial growth and where a defect is likely to occur, and the gate electrode lacks such a location and thus avoids an increase in normalized ON resistance. Therefore, the breakdown voltage remains high without increasing the ON resistance.
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Citations
23 Claims
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1. A semiconductor device comprising:
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a semiconductor substrate having a top surface and a back surface, wherein the back surface is opposite to the top surface;
a source region of a first conduction type, which extends in the substrate perpendicularly from the top surface;
a base region of a second conduction type, which extends perpendicularly from the top surface, wherein the base region has a first surface and a second surface, the second surface being opposite to the first surface, wherein the first surface of the base region contacts the source region;
a drift region of the first conduction type, wherein the drift region has an impurity concentration lower than that of the source region and extends perpendicularly from the top surface and contacts the second surface of the base region;
a drain region extending perpendicularly from the top surface in the drift region;
a gate insulating film formed on a surface that defines a trench, wherein the gate insulating film extends perpendicularly from the top surface and extends in a lateral direction from the source region to the drift region through the base region; and
a gate electrode formed on a surface of the gate insulating film such that, when a voltage is applied to the gate electrode, a channel region is generated in the vicinity of a surface of the base region adjacent to the trench, wherein the flow of the channel occurs in the lateral direction. - View Dependent Claims (2, 3, 4, 5, 6, 7)
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8. A semiconductor device comprising:
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a semiconductor substrate, which forms a source region of a first conduction type, wherein the semiconductor substrate has a top surface and a back surface, wherein the back surface is opposite to the top surface;
a base region of a second conduction type, wherein the base region extends perpendicularly from the top surface in the substrate;
a drift region of the first conduction type, wherein the drift region has an impurity concentration lower than that of the source region and extends perpendicularly from the top surface within the base region;
a drain region extending perpendicularly from the top surface within the drift region;
a gate insulating film formed on a surface that defines a trench, wherein the gate insulating film extends perpendicularly from the top surface and extends in a lateral direction from the source region to the drift region through the base region; and
a gate electrode formed on a surface of the gate insulating film such that, when a voltage is applied to the gate electrode, a channel region is generated in the vicinity of a surface of the base region adjacent to the trench, wherein the flow of the channel occurs in the lateral direction. - View Dependent Claims (9, 10, 11, 12, 13, 14)
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15. A semiconductor device comprising:
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a semiconductor substrate having a top surface and a back surface, wherein the back surface is opposite to the top surface;
a source region of a first conduction type, which extends in the substrate perpendicularly from the top surface;
a base region of a second conduction type, which extends perpendicularly from the top surface, wherein the base region has a first surface and a second surface, the second surface being opposite to the first surface, wherein the first surface of the base region contacts the source region;
a drift region of the first conduction type, wherein the drift region has an impurity concentration lower than that of the source region and extends perpendicularly from the top surface and contacts the second surface of the base region;
a drain region extending perpendicularly from the top surface in the drift region;
a gate insulating film formed on a surface that defines a trench, wherein the gate insulating film extends perpendicularly from the top surface and extends in a lateral direction from the source region to the drift region through the base region;
a gate electrode formed on a surface of the gate insulating film; and
at least one RESURF layer of the second conduction type, wherein the RESURF layer extends perpendicularly from the top surface in the drift region such that, when a voltage is applied to the gate electrode, a channel region is generated in the vicinity of a surface of the base region adjacent to the trench, wherein the flow of the channel occurs in the lateral direction. - View Dependent Claims (16, 17, 18)
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19. A semiconductor device comprising:
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a semiconductor substrate, which forms a source region of a first conduction type, wherein the semiconductor substrate has a top surface and a back surface, wherein the back surface is opposite to the top surface;
a base region of a second conduction type, wherein the base region extends perpendicularly from the top surface in the substrate;
a drift region of the first conduction type, wherein the drift region has an impurity concentration lower than that of the source region and extends perpendicularly from the top surface within the base region;
a drain region extending perpendicularly from the top surface within the drift region;
a gate insulating film formed on a surface that defines a trench, wherein the gate insulating film extends perpendicularly from the top surface and extends in a lateral direction from the source region to the drift region through the base region;
a gate electrode formed on a surface of the gate insulating film; and
at least one RESURF layer of the second conduction type, wherein the RESURF layer extends perpendicularly from the top surface in the drift region such that, when a voltage is applied to the gate electrode, a channel region is generated in the vicinity of a surface of the base region adjacent to the trench, wherein the flow of the channel occurs in the lateral direction. - View Dependent Claims (20, 21, 22)
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23. A method for manufacturing a semiconductor device comprising steps of:
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providing a semiconductor substrate, which forms a source region of a first conduction type and has a top surface and a back surface, wherein the back surface is opposite to the top surface;
forming a first trench to extend perpendicularly from the top surface in a predetermined area of the top surface;
depositing a base region film for forming a base region of a second conduction type on a surface defining the first trench to partially fill the first trench;
depositing a drift region film for forming a drift region of the first conduction type on the base region film in the first trench to further partially fill the first trench;
depositing a drain region film for forming a drain region of the first conduction type on the drift region film in the first trench;
polishing the base region film, the drift region film, and the drain region film;
forming a second trench extending perpendicularly from the top surface and.extending laterally from the source region to the drift region through the base region;
forming a gate insulating film on a surface defining the second trench; and
forming a gate electrode on a surface of the gate insulating film.
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Specification