Power MOS transistor and manufacturing method therefor
First Claim
1. A power Metal Oxide Semiconductor (MOS) transistor, comprising:
- a drain region of a first doping type in a semiconductor substrate, a drift region of the first doping type, a channel region of a second doping type, a source region of the first doping type and a first U-shaped trench, wherein the drain region is provided at a bottom of the semiconductor substrate, the drift region is provided above the drain region, the channel region is provided on both sides of side walls of the first U-shaped trench and above die drift region, a bottom of the first U-shaped trench extends into the drift region, a gate oxide layer covering the channel region is provided on, and the source region is provided at a top of the semiconductor substrate and above the channel region;
a channel region contact region is provided in the channel region, the doping type of the channel region contact region is die same as that of the channel region, and a doping concentration of the channel region contact region is greater than that of the channel region;
a second U-shaped trench in the semiconductor substrate, wherein the second U-shaped trench is provided below the first U-shaped trench, a opening width of the second U-shaped trench is smaller than that of the first U-shaped trench, and a depth of the second U-shaped trench is 10-100 nm;
a field oxide layer is provided hi the second U-shaped trench, a thickness of the field oxide layer is greater than that of the gate oxide layer, a charge compensation region is provided in the drift region below the field oxide layer, and the charge compensation region has the second doping type, the second U-shaped trench extends a field oxide stress transition region between the field oxide layer and the gate oxide layer, and a thickness of a bottom portion of the field oxide layer is thicker than a thickness of side portions of the field oxide layer; and
a polysilicon gate covering the gate oxide layer and the field oxide layer is provided in the first U-shaped trench and the second U-shaped trench.
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Abstract
The present invention discloses a power Metal Oxide Semiconductor (MOS) transistor, wherein a second U-shaped trench is formed below a first U-shaped trench, so that a field oxidation stress transition region can be extended, so as to greatly reduce current leakage caused by the field oxidation stress and improve the reliability of the device; and a charge compensation region is provided in a drift region at the bottom of the second U-shaped trench, and a super-junction structure is formed between the charge compensation region and the drift region to improve the breakdown voltage of the power device. According to the present invention, the second U-shaped trench and the charge compensation region are formed by a self-aligning process, so that the technical process is simple, reliable and easy to control, and can reduce the manufacturing cost of the power MOS transistor and improve its yield.
5 Citations
4 Claims
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1. A power Metal Oxide Semiconductor (MOS) transistor, comprising:
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a drain region of a first doping type in a semiconductor substrate, a drift region of the first doping type, a channel region of a second doping type, a source region of the first doping type and a first U-shaped trench, wherein the drain region is provided at a bottom of the semiconductor substrate, the drift region is provided above the drain region, the channel region is provided on both sides of side walls of the first U-shaped trench and above die drift region, a bottom of the first U-shaped trench extends into the drift region, a gate oxide layer covering the channel region is provided on, and the source region is provided at a top of the semiconductor substrate and above the channel region; a channel region contact region is provided in the channel region, the doping type of the channel region contact region is die same as that of the channel region, and a doping concentration of the channel region contact region is greater than that of the channel region; a second U-shaped trench in the semiconductor substrate, wherein the second U-shaped trench is provided below the first U-shaped trench, a opening width of the second U-shaped trench is smaller than that of the first U-shaped trench, and a depth of the second U-shaped trench is 10-100 nm; a field oxide layer is provided hi the second U-shaped trench, a thickness of the field oxide layer is greater than that of the gate oxide layer, a charge compensation region is provided in the drift region below the field oxide layer, and the charge compensation region has the second doping type, the second U-shaped trench extends a field oxide stress transition region between the field oxide layer and the gate oxide layer, and a thickness of a bottom portion of the field oxide layer is thicker than a thickness of side portions of the field oxide layer; and a polysilicon gate covering the gate oxide layer and the field oxide layer is provided in the first U-shaped trench and the second U-shaped trench. - View Dependent Claims (2, 3, 4)
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Specification