US5741396A
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Isotropic nitride stripping
Assignee: Texas Instruments Inc
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Filing: 1994-04-29
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Granted: 1998-04-21
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Expires: 2014-04-29
Abstract
Abstract A dry etch process for stripping LOCOS nitride masks (302) with fluorine based removal of oxynitride (312) followed by fluorine plus chlorine based removal of nitride (302) and any silicon buffer layer (303) without removal of pad oxide (304).
Inventors
- 👤 Lee M. Loewenstein
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-09 09:08
CPC Classifications
H; H10; H10P; H10P72/00; H10P72/04; H10P72/0402; H10P72/0418; H10P72/0421; H10P50/00; H10P50/20; H10P50/26; H10P50/264; H10P50/266; H10P50/267; H10P50/268; H10P50/28; H10P50/282; H10P50/283; H10W; H10W10/00; H10W10/01; H10W10/011; H10W10/012; H10W10/0121; H10W10/10; H10W10/13
Claims Analysis
Total Claims: 13
Claim 1
Independent Claim
51 words
A method of isotropic dry etching silicon nitride, comprising the steps of: (a) exposing silicon nitride to a gas mixture including fluorine and chlorine sources plus a control gas selected from the group consisting of an oxygen source, a nitrogen source, and a mixture thereof, whereby said silicon nitride is removed.
Claim 2
Independent Claim
51 words
A method of isotropic dry etching silicon nitride, comprising the steps of: (a) exposing silicon nitride to a gas mixture including fluorine and chlorine sources plus a control gas selected from the group consisting of an oxygen source, a nitrogen source, and a mixture thereof, whereby said silicon nitride is removed.
Claim 3
Dependent Claim
26 words
The method of claim 1, wherein: (a) said gas mixture of step (a) of claim 1 is excited in a plasma remote from said silicon nitride.
Claim 4
Dependent Claim
21 words
The method of claim 1, wherein: (a) said gas mixture of step (a) of claim 1 contains more oxygen than fluorine.
Claim 5
Dependent Claim
21 words
The method of claim 1, wherein: (a) said gas mixture of step (a) of claim 1 contains more nitrogen than fluorine.
Claim 6
Dependent Claim
31 words
The method of claim 1, wherein: (a) the ratios of nitrogen to fluorine and oxygen to fluorine are both greater than the ratio of chlorine to fluorine in said gas mixture.
Claim 7
Dependent Claim
48 words
The method of claim 1, wherein: (a) said gas mixture removes silicon nitride at a rate of at least 10 times the rate it removes silicon oxide; and (b) the gas mixture removes silicon nitride at a rate of at least 2 times the rate it removes polysilicon.
Claim 8
Dependent Claim
47 words
The method of claim 6, wherein: (a) said gas mixture is excited in a remote plasma; and (b) said gas mixture included NF 3 as a fluorine source, Cl 2 as a chlorine source, N 2 as a nitrogen source, and O 2 as an oxygen source.
Claim 9
Dependent Claim
39 words
The method of claim 7, wherein: (a) the ratio of N 2 to NF 3 and the ratio of O 2 to NF 3 are both at least 10 times the ratio of Cl 2 to NF 3 .
Claim 10
Dependent Claim
34 words
An isotropic dry etch mixture for etching silicon nitride, comprising: (a) activated species from a remote excitation of a mixture of a fluorine source, a chlorine source, a nitrogen source, and an oxygen source.
Claim 11
Dependent Claim
34 words
An isotropic dry etch mixture for etching silicon nitride, comprising: (a) activated species from a remote excitation of a mixture of a fluorine source, a chlorine source, a nitrogen source, and an oxygen source.
Claim 12
Dependent Claim
37 words
The etch mixture of claim 9, wherein: (a) said fluorine source includes NF 3 , said chlorine source includes Cl 2 , said nitrogen source includes N 2 , and said oxygen source includes O 2 .
Claim 13
Dependent Claim
40 words
The etch mixture of claim 10, wherein: (a) the ratio of N 2 to NF 3 and the ratio of O 2 to NF 3 are both at least 10 times the ratio of Cl 2 to NF 3 .
References Cited (Backward Citations)
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