US6051504A
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US
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Anisotropic and selective nitride etch process for high aspect ratio features in high density plasma
Assignee: International Business Machines Corp
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Filing: 1997-08-15
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Granted: 2000-04-18
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Expires: 2017-08-15
Abstract
Abstract A process for etching silicon nitride from a multilayer structure which uses an etchant gas including a fluorocarbon gas, a hydrogen source, and a weak oxidant. A power source, such as an RF power source, is applied to the structure to control the directionality of the high density plasma formed by exciting the etchant gas. The power source that controls the directionality of the plasma is decoupled from the power source used to excite the etchant gas. The fluorocarbon gas is selected from CF 4 , C 2 F 6 , and C 3 F 8 ; the hydrogen source is selected from CH 2 F 2 , CH 3 F, and H 2 ; and the weak oxidant is selected from CO, CO 2 , and O 2 .
Inventors
- 👤 Michael David Armacost
- 👤 Richard Stephen Wise
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-08 12:53
CPC Classifications
H; H10; H10P; H10P50/00; H10P50/20; H10P50/28; H10P50/282; H10P50/283
Claims Analysis
Total Claims: 18
Claim 1
Independent Claim
78 words
A method for anisotropically etching a silicon nitride layer from a multilayer structure, said method comprising the steps of: exciting an etchant gas comprising a fluorocarbon gas, a hydrogen source, and a weak oxidant to form a high density plasma; applying a power source to said multilayer structure to control the directionality of said high density plasma on said multilayer structure; and introducing said high density plasma to said silicon nitride layer to etch said silicon nitride layer.
Claim 2
Independent Claim
78 words
A method for anisotropically etching a silicon nitride layer from a multilayer structure, said method comprising the steps of: exciting an etchant gas comprising a fluorocarbon gas, a hydrogen source, and a weak oxidant to form a high density plasma; applying a power source to said multilayer structure to control the directionality of said high density plasma on said multilayer structure; and introducing said high density plasma to said silicon nitride layer to etch said silicon nitride layer.
Claim 3
Dependent Claim
29 words
The method of claim 1, wherein said fluorocarbon gas is selected from the group consisting CF 4 , C 2 F 6 , and C 3 F 8 .
Claim 4
Dependent Claim
28 words
The method of claim 1, wherein said hydrogen source is selected from the group consisting of CH 2 F 2 , CH 3 F, and H 2 .
Claim 5
Dependent Claim
24 words
The method of claim 1, wherein said weak oxidant is selected from the group consisting of CO, CO 2 , and O 2 .
Claim 6
Dependent Claim
46 words
The method of claim 1, wherein: said fluorocarbon gas is added in an amount of about 4-20% by volume; said hydrogen source is added in an amount of about 10-30% by volume; and said weak oxidant is added in an amount of about 40-70% by volume.
Claim 7
Dependent Claim
28 words
The method of claim 1, wherein: said fluorocarbon gas is C 2 F 6 ; said hydrogen source is CH 3 F; and said weak oxidant is CO.
Claim 8
Dependent Claim
25 words
The method of claim 1, wherein the step of exciting said etchant gas uses a coil, and said power source is decoupled from said coil.
Claim 9
Dependent Claim
30 words
The method of claim 1, wherein the step of exciting said etchant gas includes forming said high density plasma having a density of at least 10 11 cm -1 .
Claim 10
Dependent Claim
42 words
The method of claim 1, further comprising the steps of: introducing said etchant gas into a chamber; and maintaining the pressure of said chamber at 1 to 20 millitorrs by utilizing a vacuum pump and coupling said vacuum pump to said chamber.
Claim 11
Dependent Claim
31 words
The method of claim 1, wherein the step of applying a power source comprises applying an RF power source to the side of said multilayer structure opposite said silicon nitride layer.
Claim 12
Independent Claim
95 words
A method for anisotropically etching a silicon nitride layer from a multilayer structure, said method comprising the steps of: exciting an etchant gas comprising a fluorocarbon gas, a hydrogen source, and a weak oxidant by exposing said etchant gas to a first power source to form a high density plasma; applying a second power source, decoupled from said first power source, to said multilayer structure to control the directionality of said high density plasma on said multilayer structure; and introducing said high density plasma to said silicon nitride layer to etch said silicon nitride layer.
Claim 13
Independent Claim
95 words
A method for anisotropically etching a silicon nitride layer from a multilayer structure, said method comprising the steps of: exciting an etchant gas comprising a fluorocarbon gas, a hydrogen source, and a weak oxidant by exposing said etchant gas to a first power source to form a high density plasma; applying a second power source, decoupled from said first power source, to said multilayer structure to control the directionality of said high density plasma on said multilayer structure; and introducing said high density plasma to said silicon nitride layer to etch said silicon nitride layer.
Claim 14
Dependent Claim
28 words
The method of claim 11, wherein: said fluorocarbon gas is C 2 F 6 ; said hydrogen source is CH 3 F; and said weak oxidant is CO.
Claim 15
Independent Claim
187 words
A method for anisotropically etching a silicon nitride layer from a multilayer structure including said silicon nitride layer, a substrate, a silicon oxide layer, and a resist layer, said method comprising the steps of: introducing an etchant gas into a chamber, wherein said etchant gas comprises: (a) a fluorocarbon gas selected from the group consisting of CF 4 , C 2 F 6 , and C 3 F 8 ; (b) a hydrogen source selected from the group consisting of CH 2 F 2 , CH 3 F, and H 2 ; and (c) a weak oxidant selected from the group consisting of CO, CO 2 , and O 2 ; exciting said etchant gas by exposing said etchant gas to a first power source to form a high density plasma; controlling the bias of said high density plasma on said multilayer structure by applying a second power source, decoupled from said first power source, to said multilayer structure; and introducing said high density plasma to said silicon nitride layer to etch a feature in said silicon nitride layer having an aspect ratio of at least 2:1.
Claim 16
Independent Claim
187 words
A method for anisotropically etching a silicon nitride layer from a multilayer structure including said silicon nitride layer, a substrate, a silicon oxide layer, and a resist layer, said method comprising the steps of: introducing an etchant gas into a chamber, wherein said etchant gas comprises: (a) a fluorocarbon gas selected from the group consisting of CF 4 , C 2 F 6 , and C 3 F 8 ; (b) a hydrogen source selected from the group consisting of CH 2 F 2 , CH 3 F, and H 2 ; and (c) a weak oxidant selected from the group consisting of CO, CO 2 , and O 2 ; exciting said etchant gas by exposing said etchant gas to a first power source to form a high density plasma; controlling the bias of said high density plasma on said multilayer structure by applying a second power source, decoupled from said first power source, to said multilayer structure; and introducing said high density plasma to said silicon nitride layer to etch a feature in said silicon nitride layer having an aspect ratio of at least 2:1.
Claim 17
Dependent Claim
28 words
The method of claim 13, wherein: said fluorocarbon gas is C 2 F 6 ; said hydrogen source is CH 3 F; and said weak oxidant is CO.
Claim 18
Dependent Claim
16 words
The method of claim 13, wherein said feature has an aspect ratio of at least 6:1.
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| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
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| 3.5 Years (Year 4) | 2003-04-18 | 2003-10-18 | 2004-04-18 | $2000.00 | Window Closed / Lapsed |
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