Patent US6471833B2 successfully refreshed from Google Patents.
US6471833B2
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High etch rate method for plasma etching silicon nitride
Assignee: Applied Materials Inc
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Filing: 2001-05-11
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Granted: 2002-10-29
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Expires: 2021-05-11
Abstract
Abstract This invention is directed to a method for rapid plasma etching of materials which are difficult to etch at a high rate. The method is particularly useful in plasma etching silicon nitride layers more than five microns thick. The method includes the use of a plasma source gas that includes an etchant gas and a sputtering gas. Two separate power sources are used in the etching process and the power to each power source as well as the ratio between the flow rates of the etchant gas and sputtering gas can be advantageously adjusted to obtain etch rates of silicon nitride greater than two microns per minute. Additionally, an embodiment of the method of the invention provides a two etch step process which combines a high etch rate process with a low etch rate process to achieve high throughput while minimizing the likelihood of damage to underlying layers. The first etch step of the two-step method provides a high etch rate of about two microns per minute to remove substantially all of a layer to be etched. In the second step, a low etch rate process having an etch rate below about two microns per minute is used to remove any residual material not removed by the first etch step.
Inventors
- 👤 Ajay Kumar
- 👤 Anisul Khan
- 👤 Jeffrey D Chin
- 👤 Dragan V Podlesnik
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-07 03:40
CPC Classifications
H; H10; H10P; H10P72/00; H10P72/04; H10P72/0402; H10P72/0418; H10P72/0421; H01; H01J; H01J37/00; H01J37/32; H01J37/32009; H01J37/32082; H01J37/321; H01J37/32917; H01J37/32935; H10P50/00; H10P50/20; H10P50/24; H10P50/242
Claims Analysis
Total Claims: 31
Claim 1
Independent Claim
70 words
A method of plasma etching a silicon nitride layer which is about five microns thick or more prior to etching, the method comprising: (a) forming aplasma from a gaseous mixture,which plasma consists essentially of a fluorine-containing chemical etchant component and an ion bombardment component which produces sputtering of a surface being etched; and (b) etching said silicon nitride layer at an etch rate of greater than 2 microns per minute.
Claim 2
Independent Claim
70 words
A method of plasma etching a silicon nitride layer which is about five microns thick or more prior to etching, the method comprising: (a) forming aplasma from a gaseous mixture,which plasma consists essentially of a fluorine-containing chemical etchant component and an ion bombardment component which produces sputtering of a surface being etched; and (b) etching said silicon nitride layer at an etch rate of greater than 2 microns per minute.
Claim 3
Dependent Claim
24 words
A method according to claim 1 wherein said silicon nitride layer has a thickness between about 10 microns to about 50 microns before etching.
Claim 4
Dependent Claim
24 words
A method according to claim 1 wherein said plasma is formed by exposing said gaseous mixture to energy provided by separately controllable power sources.
Claim 5
Dependent Claim
20 words
The method according to claim 3 wherein at least one of said power sources is inductively coupled to said plasma.
Claim 6
Dependent Claim
15 words
A method according to claim 1 wherein said etchant gas comprises a multiple-fluorine-atom containing compound.
Claim 7
Dependent Claim
14 words
A method according to claim 5 wherein said etchant gas comprises SF 6 .
Claim 8
Dependent Claim
14 words
A method according to claim 1 wherein said sputtering gas is an inert gas.
Claim 9
Dependent Claim
23 words
A method according to claim 7 wherein said inert gas is selected from the group consisting of: Ar, He, Kr, Xe and Ne.
Claim 10
Independent Claim
173 words
A method for plasma etching a silicon nitride layer which is about five microns thick or more prior to etching comprising: (a) forming a first plasma from a first gaseous mixture, which plasma consists essentially of a fluorine-containing etchant component and an ion bombardment component which produces sputtering of a surface being etched; (b) etching a first portion of said silicon nitride layer with said first plasma at a first etch rate greater than about 2 microns per minute; (c) forming a second plasma from a second gaseous mixture, which plasma consists essentially of a fluorine-containing etchant component and an ion bombardment component which produces sputtering of a surface being etched, wherein a flow rate of said etchant component, or a flow rate of said ion bombardment component, or a flow rate of both is reduced from a flow rate of said component in step (a); and (d) etching a second portion of said silicon nitride layer with said second plasma at an etch rate which is less than said first etch rate.
Claim 11
Independent Claim
173 words
A method for plasma etching a silicon nitride layer which is about five microns thick or more prior to etching comprising: (a) forming a first plasma from a first gaseous mixture, which plasma consists essentially of a fluorine-containing etchant component and an ion bombardment component which produces sputtering of a surface being etched; (b) etching a first portion of said silicon nitride layer with said first plasma at a first etch rate greater than about 2 microns per minute; (c) forming a second plasma from a second gaseous mixture, which plasma consists essentially of a fluorine-containing etchant component and an ion bombardment component which produces sputtering of a surface being etched, wherein a flow rate of said etchant component, or a flow rate of said ion bombardment component, or a flow rate of both is reduced from a flow rate of said component in step (a); and (d) etching a second portion of said silicon nitride layer with said second plasma at an etch rate which is less than said first etch rate.
Claim 12
Dependent Claim
21 words
The method of claim 9 , wherein said first gaseous mixture consists essentially of a fluorine-containing compound and an inert gas.
Claim 13
Dependent Claim
21 words
The method of claim 10 , wherein said second gaseous mixture consists essentially of a fluorine-containing compound and an inert gas.
Claim 14
Dependent Claim
21 words
The method of claim 9 , wherein said second gaseous mixture consists essentially of a fluorine-containing compound and an inert gas.
Claim 15
Dependent Claim
36 words
The method of claim 10 or claim 11 or claim 12 , wherein said fluorine-containing compound is SF 6 and said inert gas is selected from the group consisting of: Ar, He, Kr, Xe and Ne.
Claim 16
Dependent Claim
40 words
The method of claim 10 or claim 11 or claim 12 , wherein a flow rate of said etchant gas in said first gaseous mixture is greater than a flow rate of said etchant gas in said second gaseous mixture.
Claim 17
Dependent Claim
44 words
The method of claim 14 , wherein said flow rate of said etchant gas in said second gaseous mixture is within a range of about 66 percent to about 78 percent of said flow rate of said etchant gas in said first gaseous mixture.
Claim 18
Dependent Claim
34 words
The method of claim 14 , wherein a flow rate of said sputtering gas in said second gaseous mixture is less than a flow rate of said sputtering gas in said first gaseous mixture.
Claim 19
Dependent Claim
44 words
The method of claim 16 , wherein said flow rate of said sputtering gas in said second gaseous mixture is within a range of about 60 percent to about 65 percent of said flow rate of said sputtering gas in said first gaseous mixture.
Claim 20
Dependent Claim
34 words
The method of claim 9 , wherein a flow rate of said etchant gas in said first gaseous mixture is greater than a flow rate of said etchant gas in said second gaseous mixture.
Claim 21
Dependent Claim
37 words
The method of claim 9 or claim 18 , wherein a flow rate of said sputtering gas in said second gaseous mixture is less than a flow rate of said sputtering gas in said first gaseous mixture.
Claim 22
Dependent Claim
31 words
The method of claim 9 , wherein etching of said second portion is conducted at a second pressure which is lower than a first pressure used for etching said first portion.
Claim 23
Dependent Claim
26 words
The method of claim 20 , wherein said second pressure is within a range of about 25 percent to about 50 percent of said first pressure.
Claim 24
Dependent Claim
18 words
The method of claim 9 , wherein said first portion includes substantially all of said silicon nitride layer.
Claim 25
Dependent Claim
16 words
The method of claim 9 , wherein said first portion is greater than said second portion.
Claim 26
Dependent Claim
79 words
The method of claim 9 , wherein said first plasma is formed using a first energy provided from a first power source at a first power level and a second energy provided from a second power source at a second power level, and wherein said second plasma is formed using a third energy provided from said first power source at a third power level and a fourth energy provided from said second power source at a fourth power level.
Claim 27
Dependent Claim
42 words
The method of claim 24 , wherein the total power provided at said first power level in combination with said second power level is greater than the total power provided at said third power level in combination with said fourth power level.
Claim 28
Dependent Claim
43 words
The method of claim 24 , wherein the total power provided by said first power level in combination with said second power level is approximately equal to the total power provided at said third power level in combination with said fourth power level.
Claim 29
Dependent Claim
31 words
The method of claim 24 , wherein said first power level is the same as said third power level, and said fourth power level is less than said second power level.
Claim 30
Dependent Claim
22 words
The method of claim 24 , wherein a first power source is inductively coupled to said first plasma and said second plasma.
Claim 31
Dependent Claim
57 words
The method of claim 24 , wherein said third power level provides a greater percentage of the total power provided by a combination of said third and said fourth power levels than said first power level provides as a percentage of the total power provided by said first power level in combination with said second power level.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
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| 3.5 Years (Year 4) | 2005-10-28 | 2006-04-29 | 2006-10-29 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2009-10-28 | 2010-04-29 | 2010-10-29 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2013-10-28 | 2014-04-29 | 2014-10-29 | $7700.00 | Window Closed / Lapsed |