Power MOS device with asymmetrical channel structure for enhanced linear operation capability
First Claim
1. A method of making a power MOSFET type device for stable linear operation, comprising:
- providing a substrate including an active device region of a first dopant type;
forming a body region of a second dopant type opposite the first dopant type adjacent a surface of the substrate;
forming first and second source regions of the first dopant type within the body region, positioned to define separate channel regions in the body region adjacent the surface of the substrate;
forming a gate structure including first and second gate portions on the substrate surface respectively overlying the first and second channel regions;
adjusting a gate threshold voltage characteristic of each of the channel regions to produce an asymmetric gate threshold voltage characteristic in the device.
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Abstract
A power MOSFET type device, which can include an IGBT or other VDMOS device having similar forward transfer characteristics, is formed with an asymmetrical channel, to produce different gate threshold voltage characteristics in different parts of the device. The different gate threshold voltage characteristics can be achieved either by different source region doping concentrations or different body region doping concentrations subjacent the gate oxide, or by asymmetrical gate oxide thicknesses. The portion of overall channel affected can be 50% or such other proportion as the designer chooses, to reduce the zero temperature coefficient point of the device and improve its Safe Operating Area in linear operation, while retaining low conduction loss. Multiple power MOSFET devices with asymmetrical channels can easily be used safely in parallel linear power amplifier circuits.
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Citations
11 Claims
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1. A method of making a power MOSFET type device for stable linear operation, comprising:
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providing a substrate including an active device region of a first dopant type;
forming a body region of a second dopant type opposite the first dopant type adjacent a surface of the substrate;
forming first and second source regions of the first dopant type within the body region, positioned to define separate channel regions in the body region adjacent the surface of the substrate;
forming a gate structure including first and second gate portions on the substrate surface respectively overlying the first and second channel regions;
adjusting a gate threshold voltage characteristic of each of the channel regions to produce an asymmetric gate threshold voltage characteristic in the device. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
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10. A method of making a vertical double-diffused power MOSFET type device for stable linear operation, comprising:
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providing a substrate including an active device region of a first dopant type forming a vertical drain region;
forming a body region of a second dopant type opposite the first dopant type adjacent a surface of the substrate bounded on opposite sides by the vertical drain region;
forming first and second source regions of the first dopant type within the body region, positioned to define separate channel regions in the body region adjacent the surface of the substrate, each channel region extending to the vertical drain region on opposite sides of the body region;
forming a gate structure including first and second gate portions on the substrate surface respectively overlying the first and second channel regions;
adjusting a gate threshold voltage characteristic of each of the channel regions to produce an asymmetric gate threshold voltage characteristic in the device. - View Dependent Claims (11)
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Specification