Low resistance gate for power MOSFET applications and method of manufacture
First Claim
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1. A method of forming a trench gate field effect transistor, comprising:
- forming a trench in a semiconductor region that comprises a substrate of a first conductivity type and a silicon region of the first conductivity type over the substrate, the silicon region having a lower doping concentration than the substrate;
forming a dielectric layer lining sidewalls and bottom of the trench and extending over mesa regions adjacent the trench;
forming a conductive seed layer in a bottom portion of the trench over the dielectric layer;
growing a low resistance material over the conductive seed layer, wherein the low resistance material is selective to the conductive seed layer; and
forming a well region of a second conductivity type in the silicon region, wherein the conductive seed layer has an upper surface below a bottom surface of the well region.
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Abstract
A trench gate field effect transistor is formed as follows. A trench is formed in a semiconductor region, followed by a dielectric layer lining sidewalls and bottom of the trench and extending over mesa regions adjacent the trench. A conductive seed layer is formed in a bottom portion of the trench over the dielectric layer. A low resistance material is grown over the conductive seed layer, wherein the low resistance material is selective to the conductive seed layer.
28 Citations
27 Claims
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1. A method of forming a trench gate field effect transistor, comprising:
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forming a trench in a semiconductor region that comprises a substrate of a first conductivity type and a silicon region of the first conductivity type over the substrate, the silicon region having a lower doping concentration than the substrate; forming a dielectric layer lining sidewalls and bottom of the trench and extending over mesa regions adjacent the trench; forming a conductive seed layer in a bottom portion of the trench over the dielectric layer; growing a low resistance material over the conductive seed layer, wherein the low resistance material is selective to the conductive seed layer; and forming a well region of a second conductivity type in the silicon region, wherein the conductive seed layer has an upper surface below a bottom surface of the well region. - View Dependent Claims (2, 3, 4, 5, 6, 7)
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8. A method of forming a shielded gate field effect transistor, comprising:
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forming a trench in a semiconductor region that comprises a substrate of a first conductivity type and a silicon region of the first conductivity type over the substrate, the silicon region having a lower doping concentration than the substrate; lining lower sidewalls and bottom of the trench with shield dielectric; filling a lower portion of the trench with a shield electrode; forming an inter-electrode dielectric over the shield electrode; forming a dielectric layer lining upper trench sidewalls and extending over mesa regions adjacent the trench; forming a conductive seed layer over the inter-electrode dielectric layer; growing a low resistance material over the conductive seed layer, wherein the low resistance material is selective to the conductive seed layer; and forming a well region of a second conductivity type in the silicon region, wherein the conductive seed layer has an upper surface below a bottom surface of the well region. - View Dependent Claims (9, 10, 11, 12, 13, 14)
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15. A method of forming a trench gate field effect transistor, comprising:
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forming trenches in a semiconductor region; forming a dielectric layer lining sidewalls and bottom of each trench and extending over mesa regions adjacent the trenches; forming a conductive seed layer in a bottom portion of each trench over the dielectric layer; and growing a low resistance material over the conductive seed layer in each trench, wherein the low resistance material is selective to the conductive seed layer and is grown to a height below a top surface of the mesa regions adjacent the trenches. - View Dependent Claims (16, 17, 18, 19, 20, 21)
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22. A method of forming a shielded gate field effect transistor, comprising:
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forming trenches in a semiconductor region; lining lower sidewalls and bottom of each trench with a shield dielectric; filling a lower portion of each trench with a shield electrode; forming a dielectric layer over the shield electrode in each trench; forming a conductive seed layer in each trench over the dielectric layer; and growing a low resistance material over the conductive seed layer in each trench, wherein the low resistance material is selective to the conductive seed layer and is grown to a height below a top surface of the mesa regions adjacent the trenches. - View Dependent Claims (23, 24, 25, 26, 27)
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Specification