Self-aligned contact for replacement gate devices
First Claim
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1. A semiconductor structure comprising:
- a gate stack located on a semiconductor substrate, wherein said gate stack comprises, from top to bottom, a U-shaped work function metal portion, a U-shaped barrier metal portion and a gate conductor portion;
a planarization dielectric layer laterally surrounding said gate stack, wherein a top surface of said gate stack is recessed relative to a top surface of said planarization dielectric layer; and
an etch stop layer contiguously located on said recessed top surface of said gate stack and said top surface of said planarization dielectric layer, wherein said etch stop layer includes a first portion located on said planarization dielectric layer and a second portion located on said gate stack and having a vertically offset bottom surface relative to an interface between said planarization dielectric layer and said first portion.
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Abstract
A conductive top surface of a replacement gate stack is recessed relative to a top surface of a planarization dielectric layer by at least one etch. A dielectric capping layer is deposited over the planarization dielectric layer and the top surface of the replacement gate stack so that the top surface of a portion of the dielectric capping layer over the replacement gate stack is vertically recessed relative to another portion of the dielectric layer above the planarization dielectric layer. The vertical offset of the dielectric capping layer can be employed in conjunction with selective via etch processes to form a self-aligned contact structure.
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Citations
20 Claims
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1. A semiconductor structure comprising:
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a gate stack located on a semiconductor substrate, wherein said gate stack comprises, from top to bottom, a U-shaped work function metal portion, a U-shaped barrier metal portion and a gate conductor portion; a planarization dielectric layer laterally surrounding said gate stack, wherein a top surface of said gate stack is recessed relative to a top surface of said planarization dielectric layer; and an etch stop layer contiguously located on said recessed top surface of said gate stack and said top surface of said planarization dielectric layer, wherein said etch stop layer includes a first portion located on said planarization dielectric layer and a second portion located on said gate stack and having a vertically offset bottom surface relative to an interface between said planarization dielectric layer and said first portion. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20)
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Specification