Patent US4832787A successfully refreshed from Google Patents.
US4832787A
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Gas mixture and method for anisotropic selective etch of nitride
Assignee: International Business Machines Corp
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Filing: 1988-02-19
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Granted: 1989-05-23
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Expires: 2008-02-19
Abstract
Abstract A gas mixture for use in the selective dry etching of a nitride insulator layer relative to an oxide insulator layer comprising: a gas mixture containing chlorine and oxygen. The oxygen in this gas mixture must comprise 15% or less by volume. In a preferred process embodiment for ethcing Si 3 N 4 and leaving a layer of SiO 2 therebelow, Cl 2 gas may be used in combination with 12% or less oxygen by volume. Etch selectivity of greater than five to one is achieved with this gas mixture when a plasma RF frequency of less than 1 MHz is utilized. When a high frequency RF component in the range of 10-27 MHz is added to the RF excitation signal, then an etch uniformity of better than 3% is achieved.
Inventors
- 👤 James A. Bondur
- 👤 Francois D. Martinet
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-31 08:05
CPC Classifications
H; H10; H10P; H10P50/00; H10P50/20; H10P50/28; H10P50/282; H10P50/283
Claims Analysis
Total Claims: 25
Claim 1
Independent Claim
49 words
A gas mixture for use in the selective dry etching of a nitride insulator layer relative to an oxide insulator layer, comprising: a gas mixture containing at least 70% by volume of chlorine; and oxygen; wherein said oxygen comprises no more than 1-15% by volume of said gas mixture.
Claim 2
Dependent Claim
49 words
A gas mixture for use in the selective dry etching of a nitride insulator layer relative to an oxide insulator layer, comprising: a gas mixture containing at least 70% by volume of chlorine; and oxygen; wherein said oxygen comprises no more than 1-15% by volume of said gas mixture.
Claim 3
Dependent Claim
19 words
A gas mixture as defined in claim 1, wherein said oxygen comprises less than 12% of said gas mixture.
Claim 4
Dependent Claim
13 words
A gas mixture as defined in claim 1, further comprising a non-reactive gas.
Claim 5
Dependent Claim
14 words
A gas mixture as defined in claim 3, wherein said non-reactive gas is argon.
Claim 6
Dependent Claim
17 words
A gas mixture as defined in claim 1, wherein said chlorine containing gas is Cl 2 .
Claim 7
Dependent Claim
57 words
A gas mixture for use in the selective dry etching of a silicon nitride insulator layer relative to a silicon dioxide insulator layer, comprising: Cl 2 gas, wherein said Cl 2 gas is at least 70% by volume of said gas mixture; oxygen, wherein said oxygen comprises no more than 12% by volume of said gas mixture.
Claim 8
Dependent Claim
57 words
A gas mixture for use in the selective dry etching of a silicon nitride insulator layer relative to a silicon dioxide insulator layer, comprising: Cl 2 gas, wherein said Cl 2 gas is at least 70% by volume of said gas mixture; oxygen, wherein said oxygen comprises no more than 12% by volume of said gas mixture.
Claim 9
Dependent Claim
49 words
An RF gaseous plasma for use in the selective dry etching of a nitride insulator layer relative to an oxide insulator layer, comprising: chlorine species comprising at least 70% by volume of said plasma; and oxygen; wherein said oxygen comprises no more than 15% by volume of said plasma.
Claim 10
Dependent Claim
49 words
An RF gaseous plasma for use in the selective dry etching of a nitride insulator layer relative to an oxide insulator layer, comprising: chlorine species comprising at least 70% by volume of said plasma; and oxygen; wherein said oxygen comprises no more than 15% by volume of said plasma.
Claim 11
Dependent Claim
20 words
A plasma as defined in claim 7, wherein said oxygen comprises no more than 12% by volume of said plasma.
Claim 12
Dependent Claim
12 words
A plasma as defined in claim 8, further including a non-reactive gas.
Claim 13
Dependent Claim
87 words
A process for selectively etching a nitride insulator layer relative to an oxide insulator layer, comprising the steps of: disposing a nitride insulator layer to be etched in an etching chamber; exposing said nitride layer to a gaseous RF plasma that includes chlorine species, wherein said plasma is formed from a mixture of a gas containing oxygen in the range of 1-15% by volume, and using an RF excitation signal with the majority of power in the signal at a first frequency of less than 1 MHz.
Claim 14
Dependent Claim
87 words
A process for selectively etching a nitride insulator layer relative to an oxide insulator layer, comprising the steps of: disposing a nitride insulator layer to be etched in an etching chamber; exposing said nitride layer to a gaseous RF plasma that includes chlorine species, wherein said plasma is formed from a mixture of a gas containing oxygen in the range of 1-15% by volume, and using an RF excitation signal with the majority of power in the signal at a first frequency of less than 1 MHz.
Claim 15
Dependent Claim
16 words
A process as defined in claim 10, wherein said chamber pressure is greater than 0.4 Torr.
Claim 16
Dependent Claim
75 words
A process defined in claim 11, wherein said plasma exposing step comprises the step of forming said plasma with an RF frequency excitation including said first frequency signal with a frequency of less than said 1 MHz at a first power, and including a second frequency signal with a frequency at least 10 times greater than said first frequency signal and at a second power which is less than a half of said first power.
Claim 17
Dependent Claim
44 words
A process as defined in claim 12, wherein said first frequency signal has a first power in the range of at least 200 W and wherein said second frequency signal is greater than 10 MHz at a second power of less than 50 W.
Claim 18
Dependent Claim
23 words
A process as defined in claim 11, wherein said mixture in said exposing step contains no more than 12% by volume of oxygen.
Claim 19
Dependent Claim
18 words
A process as defined in claim 11, wherein said mixture in said exposing step includes a non-reactive gas.
Claim 20
Dependent Claim
13 words
A process as defined in claim 13, wherein said non-reactive gas is argon.
Claim 21
Dependent Claim
22 words
A process as defined in claim 10, wherein the chlorine-containing gas in said mixture in said exposing step comprises Cl 2 gas.
Claim 22
Dependent Claim
40 words
A process as defined in claim 12, comprising the step of generating said RF gaseous plasma with said first frequency signal being in the range of 300-900 kHz, with said second frequency signal being in the range of 13-27 MHz.
Claim 23
Dependent Claim
114 words
Process for selectively etching a nitride insulator layer relative to an oxide insulator layer, comprising the step of: exposing said nitride layer to a gaseous plasma that includes chlorine species, wherein said plasma is formed from a gas mixture containing a gas in the range of 1-15% by volume that preferentially consumes CCl x species in said plasma, and wherein said plasma frequency signal includes a first frequency component in the range of 300-900 kHz and with a power of at least 120 W, and a second frequency component which is greater than 13 MHz and has a power of less than 50 W, and in an ambient pressure of greater than 0.4 Torr.
Claim 24
Dependent Claim
114 words
Process for selectively etching a nitride insulator layer relative to an oxide insulator layer, comprising the step of: exposing said nitride layer to a gaseous plasma that includes chlorine species, wherein said plasma is formed from a gas mixture containing a gas in the range of 1-15% by volume that preferentially consumes CCl x species in said plasma, and wherein said plasma frequency signal includes a first frequency component in the range of 300-900 kHz and with a power of at least 120 W, and a second frequency component which is greater than 13 MHz and has a power of less than 50 W, and in an ambient pressure of greater than 0.4 Torr.
Claim 25
Dependent Claim
27 words
A process as defined in claim 19, further comprising the step of generating said gaseous plasma with said first frequency component in the range of 300-700 kHz.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1992-05-22 | 1992-11-21 | 1993-05-23 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1996-05-22 | 1996-11-21 | 1997-05-23 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2000-05-22 | 2000-11-21 | 2001-05-23 | $7700.00 | Window Closed / Lapsed |