Silicon-carbide trench gate MOSFETs and methods of manufacture
First Claim
1. A method for producing a semiconductor device, the method comprising:
- forming a drift region of a first conductivity type in a silicon-carbide (SiC) substrate of the first conductivity type, the drift region being formed on a front side of the SiC substrate, a back side of the SiC substrate including a drain region;
forming a shielding body region of a second conductivity type in the drift region;
forming a source region of the first conductivity type in the shielding body region;
forming a gate trench in the SiC substrate, the gate trench having a depth that is greater than a depth of the source region and less than a depth of the shielding body region;
forming a gate dielectric on a sidewall of the gate trench and a bottom surface of the gate trench, the gate dielectric on the sidewall of the gate trench defining a first interface with the shielding body region, the gate dielectric on the bottom surface of the gate trench defining a second interface with the shielding body region;
forming a gate electrode on the gate dielectric; and
forming a lateral channel region of the first conductivity type, the lateral channel region being disposed in the shielding body region and along the second interface.
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Accused Products
Abstract
In a general aspect, an apparatus can include a semiconductor substrate, a drift region disposed in the semiconductor substrate; a body region disposed in the drift region and a source region disposed in the body region. The apparatus can also include a gate trench disposed in the semiconductor substrate. The apparatus can further include a gate dielectric disposed on a sidewall and a bottom surface of the gate trench, the gate dielectric on the sidewall defining a first interface with the body region and the gate dielectric on the bottom surface defining a second interface with the body region. The apparatus can still further include a gate electrode disposed on the gate dielectric and a lateral channel region disposed in the body region, the lateral channel region being defined along the second interface.
13 Citations
20 Claims
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1. A method for producing a semiconductor device, the method comprising:
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forming a drift region of a first conductivity type in a silicon-carbide (SiC) substrate of the first conductivity type, the drift region being formed on a front side of the SiC substrate, a back side of the SiC substrate including a drain region; forming a shielding body region of a second conductivity type in the drift region; forming a source region of the first conductivity type in the shielding body region; forming a gate trench in the SiC substrate, the gate trench having a depth that is greater than a depth of the source region and less than a depth of the shielding body region; forming a gate dielectric on a sidewall of the gate trench and a bottom surface of the gate trench, the gate dielectric on the sidewall of the gate trench defining a first interface with the shielding body region, the gate dielectric on the bottom surface of the gate trench defining a second interface with the shielding body region; forming a gate electrode on the gate dielectric; and forming a lateral channel region of the first conductivity type, the lateral channel region being disposed in the shielding body region and along the second interface. - View Dependent Claims (2, 3, 4, 5, 6, 7)
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8. A method for producing a semiconductor device, the method comprising:
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forming a drift region of a first conductivity type on a silicon-carbide (SiC) substrate of the first conductivity type; forming a junction field-effect transistor (JFET) channel region of the first conductivity type on the drift region; forming a shielding body region of a second conductivity type in the JFET channel region; forming a channel stopper layer of the second conductivity type on the shielding body region; forming a source region of the first conductivity type on the channel stopper layer; forming a gate trench extending through the source region and the channel stopper layer, the gate trench terminating in the JFET channel region and having a sidewall and a bottom surface; forming a built-in channel of the first conductivity type below the gate trench, the built-in channel having a sidewall portion disposed along at least a portion of the sidewall of the gate trench and a lateral portion disposed along at least a portion of the bottom surface of the gate trench, the built-in channel having a doping concentration that is different than a doping concentration of the JFET channel region; forming a gate dielectric having a sidewall portion disposed on the sidewall of the gate trench and a lateral portion disposed on the bottom surface of the trench, the lateral portion of the gate dielectric having a thickness that is greater than or equal to two times a thickness of the sidewall portion of the gate dielectric; and forming a gate electrode on the gate dielectric. - View Dependent Claims (9, 10, 11, 12, 13, 14, 15, 16)
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17. A method for producing a semiconductor device, the method comprising:
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forming a drift region of a first conductivity type in a silicon-carbide (SiC) substrate of the first conductivity type; forming a junction field-effect transistor (JFET) channel region of the first conductivity type in the SiC substrate above the drift region; forming a shielding body region of a second conductivity type in the JFET channel region; forming a channel stopper layer of the second conductivity type on the shielding body region; forming a source region of the first conductivity type on the channel stopper layer; forming a gate trench extending through the source region and the channel stopper layer, the gate trench terminating in the JFET channel region and having a sidewall and a bottom surface, the sidewall of the gate trench defining an angle of greater than 90 degrees with the bottom surface of the gate trench; forming a built-in channel of the first conductivity type below the gate trench, the built-in channel having a sidewall portion disposed along at least a portion of the sidewall of the gate trench and a lateral portion disposed along at least a portion of the bottom surface of the gate trench, the lateral portion of the built-in channel having a threshold voltage that is less than a threshold voltage of the sidewall portion of the built-in channel; forming a gate dielectric having a sidewall portion disposed on the sidewall of the gate trench and a lateral portion disposed on the bottom surface of the trench, the lateral portion of the gate dielectric having a thickness that is greater than or equal to two times a thickness of the sidewall portion of the gate dielectric; and forming a gate electrode on the gate dielectric within the gate trench. - View Dependent Claims (18, 19, 20)
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Specification