Method of manufacturing self-aligned T-shaped gate through dual damascene
First Claim
1. A method of forming a T-shaped gate structure on the surface of a semiconductor substrate, comprising the steps of:
- providing a semiconductor substrate;
depositing a layer of insulating material over the surface of said substrate;
creating a trench in said insulating layer whereby said trench has the profile of a dual damascene structure;
temporarily applying a layer of sacrificial oxide over the surface of said dual damascene trench thereby including the surface of the surrounding substrate;
growing a layer of gate oxide at the bottom of said dual damascene trench;
depositing a layer of in-situ doped polysilicon inside said dual damascene trench thereby including the surface of the surrounding layer of insulation;
planarizing the surface of said layer of doped polysilicon essentially down to the top surface of said insulating layer; and
removing said insulating layer from above the surface of said substrate and adjacent to said dual damascene structure thereby leaving said dual damascene structure in place, whereby a portion of the insulating layer remains along the entire vertical sidewalls of said dual damascene structure.
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Accused Products
Abstract
A new method is provided to manufacture a T-shaped gate. A layer of insulation is deposited over a semiconductor surface (typically the surface of a substrate), a dual damascene structure containing a via opening and a conducting line trench is created in the layer of insulation. A layer of sacrificial oxide is grown and subsequently removed (preventing initial surface defects and providing protection during subsequent steps of etching). A layer of gate oxide is selectively grown on the bottom of the dual damascene opening. A layer of poly is deposited over the layer of insulation thereby including the dual damascene opening, the poly is planarized down to essentially the top of the dual damascene structure and the insulation is removed from above the surface of the substrate in the regions surrounding the dual damascene structure leaving the dual damascene structure in place.
115 Citations
10 Claims
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1. A method of forming a T-shaped gate structure on the surface of a semiconductor substrate, comprising the steps of:
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providing a semiconductor substrate; depositing a layer of insulating material over the surface of said substrate; creating a trench in said insulating layer whereby said trench has the profile of a dual damascene structure; temporarily applying a layer of sacrificial oxide over the surface of said dual damascene trench thereby including the surface of the surrounding substrate; growing a layer of gate oxide at the bottom of said dual damascene trench; depositing a layer of in-situ doped polysilicon inside said dual damascene trench thereby including the surface of the surrounding layer of insulation; planarizing the surface of said layer of doped polysilicon essentially down to the top surface of said insulating layer; and removing said insulating layer from above the surface of said substrate and adjacent to said dual damascene structure thereby leaving said dual damascene structure in place, whereby a portion of the insulating layer remains along the entire vertical sidewalls of said dual damascene structure. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
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10. A method of forming a T-shaped gate structure on the surface of a semiconductor substrate, comprising the steps of:
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providing a semiconductor substrate; depositing a layer of insulating material over the surface of said substrate using LPCVD, PECVD, or APCVD processing, at a temperature between about 400 to 800 degrees C. to a thickness between about 5000 to 10000 Angstrom; creating a trench in said insulating layer whereby said trench has the profile of a dual damascene structure by photolithographic exposure of said insulating layer followed by applying an anisotropically etch with a plasma gas to the surface of said layer of insulating material; temporarily applying a layer of sacrificial oxide by using a thermal oxidation of the underlying silicon or by a deposition of a suitable layer of material thereafter removing said layer of sacrificial oxide by etching; selectively growing a layer of gate oxide at the bottom of said dual damascene trench; depositing a layer of in-situ doped polysilicon inside said dual damascene trench thereby including the surface of the surrounding layer of insulating material using LPCVD at a temperature between about 500 and 700 degrees C. to a thickness between about 4000 and 10000 angstrom, using silane as a source and with the addition of phosphine to provide the needed dopant; planarizing the surface of said layer of doped polysilicon using a CMP process whereby said planarization is to proceed to essentially at or slightly below the surface of said layer of insulating material; and removing said insulating layer from above the surface of said substrate and adjacent to said dual damascene structure by performing an anisotropically etch of said insulating layer thereby leaving said dual damascene structure in place, whereby a portion of the insulating layer remains along the entire vertical sidewalls of said dual damascene structure.
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Specification