NOVEL HARD MASK REMOVAL METHOD
First Claim
1. A method of removing a hard mask used for patterning gate stacks, comprising:
- patterning gate stacks on a substrate, wherein the gate stacks include a polysilicon layer and the hard mask is deposited over the polysilicon layer to assist its patterning;
depositing a dielectric layer on the substrate after the gate stacks are patterned;
planarizing a first portion of the dielectric layer by chemical mechanical polish (CMP) to remove topography on the substrate;
removing a second portion of the dielectric layer and the hard mask by using an etching gas; and
etching the remaining dielectric layer by using a wet etching chemistry.
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Accused Products
Abstract
The embodiments of methods described in this disclosure for removing a hard mask layer(s) over a polysilicon layer of a gate stack after the gate stack is etched allows the complete removal of the hard mask layer without the assistance of photolithography. A dielectric material is deposited over the substrate with the gate stacks. The topography of the substrate is removed by chemical mechanical polishing first. Afterwards, an etching gas (or vapor) is used to etch a portion of the remaining dielectric layer and the hard mask layer. The etching gas forms an etch byproduct that deposits on the substrate surface and can be subsequently removed by heating. The etching and heating to remove etch byproduct are repeated until the hard mask layer is completed removed. Afterwards, the remaining dielectric layer is removed by wet etch. The methods described are simpler and cheaper to use than conventional methods for hard mask removal.
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Citations
20 Claims
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1. A method of removing a hard mask used for patterning gate stacks, comprising:
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patterning gate stacks on a substrate, wherein the gate stacks include a polysilicon layer and the hard mask is deposited over the polysilicon layer to assist its patterning; depositing a dielectric layer on the substrate after the gate stacks are patterned; planarizing a first portion of the dielectric layer by chemical mechanical polish (CMP) to remove topography on the substrate; removing a second portion of the dielectric layer and the hard mask by using an etching gas; and etching the remaining dielectric layer by using a wet etching chemistry. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14)
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15. A method of removing a hard mask used for patterning gate stacks, comprising:
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patterning gate stacks on a substrate, wherein the gate stacks include a polysilicon layer and the hard mask is deposited over the polysilicon layer to assist its patterning; depositing a dielectric layer on the substrate after the gate stacks are patterned; planarizing a first portion of the dielectric layer by chemical mechanical polish (CMP) to remove topography on the substrate, wherein a first etching ratio of the dielectric layer to the hard mask by the etching gas is between about 0.5 to about 2; removing a second portion of the dielectric layer and the hard mask by using an etching gas; and etching the remaining dielectric layer by using a wet etching chemistry, wherein a second etching ratio of the dielectric layer to other films on the substrate by the wet etching chemistry is greater than about 4. - View Dependent Claims (16, 17, 18, 19)
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20. A method of removing a dual-layer hard mask used for patterning gate stacks, comprising:
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patterning gate stacks on a substrate, wherein the gate stacks include a polysilicon layer and the dual-layer hard mask is deposited over the polysilicon layer to assist its patterning, wherein the dual-layer hard mask includes an oxide layer over a nitride layer; depositing a dielectric layer on the substrate after the gate stacks are patterned; planarizing a first portion of the dielectric layer by chemical mechanical polish (CMP) to remove topography on the substrate, wherein a first etching ratio of the dielectric layer to the dual-layer hard mask by the etching gas is between about 0.5 to about 2; removing a second portion of the dielectric layer and the dual-layer hard mask by a first etching gas and a second etching gas, wherein the first etching gas removes the second portion of the dielectric layer and the oxide layer of the dual-layer hard mask, and wherein the second etching gas removes the nitride layer of the dual-layer hard mask; and etching the remaining dielectric layer by using a wet etching chemistry, wherein a second etching ratio of the dielectric layer to other films on the substrate by the wet etching chemistry is greater than about 4.
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Specification