Trench power MOSFET with planarized gate bus
First Claim
1. A power MOSFET comprising:
- a substrate having a first trench and a second trench extending from a top surface of the substrate;
a source region, a channel region, and a drain region in the substrate and arranged vertically along at least a portion of a wall of the first trench;
a gate structure that extends continuously in the first and second trenches, wherein a top surface of the gate structure does not extend above the top surface of the substrate, a first portion of the gate structure acts as a gate of a vertical device in the wall of the first trench, and a second portion of the gate structure resides in the second trench; and
a metal layer that is patterned to form a source contact that overlies the first trench and contacts the source region adjacent to the first trench and a gate contact that contacts the second portion of the gate structure in the second trench.
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Accused Products
Abstract
Power MOSFETs and fabrication processes for power MOSFETs use a continuous conductive gate structure within trenches to avoid problems arising from device topology caused when a gate bus extends above a substrate surface. The conductive gate structure forms gates in device trenches in an active device region and forms a gate bus in a gate bus trench. The gate bus trench that connects to the device trenches can be wide to facilitate forming a gate contact to the gate bus, while the device trenches can be narrow to maximize device density. CMP process can be used to planarize the conductive gate structure and/or overlying insulating layers. The processes are compatible with processes forming self-aligned or conventional contacts in the active device region.
115 Citations
18 Claims
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1. A power MOSFET comprising:
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a substrate having a first trench and a second trench extending from a top surface of the substrate;
a source region, a channel region, and a drain region in the substrate and arranged vertically along at least a portion of a wall of the first trench;
a gate structure that extends continuously in the first and second trenches, wherein a top surface of the gate structure does not extend above the top surface of the substrate, a first portion of the gate structure acts as a gate of a vertical device in the wall of the first trench, and a second portion of the gate structure resides in the second trench; and
a metal layer that is patterned to form a source contact that overlies the first trench and contacts the source region adjacent to the first trench and a gate contact that contacts the second portion of the gate structure in the second trench. - View Dependent Claims (2, 3, 4, 5, 6, 8)
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7. A power MOSFET comprising:
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a substrate comprising a first trench and a second trench extending from a top surface of the substrate;
a source region, a channel region, and a drain region in the substrate and arranged vertically along at least a portion of a wall of the first trench;
a gate structure that extends continuously in the first and second trenches, wherein a top surface of the gate structure does not extend above the top surface of the substrate, a first portion of the gate structure acts as a gate of a vertical device in the wall of the first trench, and a second portion of the gate structure resides in the second trench; and
a gate contact that contacts the second portion of the gate structure, wherein the gate structure comprises;
a continuous polysilicon region that extends from the first trench to the second trench; and
a metal/silicide region in the first trench, wherein the polysilicon region surrounds the metal/suicide region and prevents direct contact between the metal/silicide and a gate oxide region. - View Dependent Claims (15, 16, 17, 18)
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9. A power MOSFET comprising
a substrate comprising a first trench and a second trench extending from a top surface of the substrate; -
a source region, a channel region, and a drain region in the substrate and arranged vertically along at least a portion of a wall of the first trench;
a gate structure that extends continuously in the first and second trenches, wherein a top surface of the gate structure does not extend above the top surface of the substrate, a first portion of the gate structure acts as a gate of a vertical device in the wall of the first trench, and a second portion of the gate structure resides in the second trench; and
a gate contact that contacts the second portion of the gate structure, wherein the gate structure comprises;
a continuous polysilicon region that extends from the first trench to the second trench; and
a metal/silicide region in the first trench, wherein the metal/suicide region extends continuously from the second trench into the first trench. - View Dependent Claims (10, 11, 12, 13, 14)
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Specification