US5922622A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Pattern formation of silicon nitride
Assignee: Vanguard International Semiconductor Corp
•
Filing: 1996-09-03
•
Granted: 1999-07-13
•
Expires: 2016-09-03
Abstract
Abstract A plasma etch method for forming a patterned silicon nitride layer within an integrated circuit. There is first provided a substrate having formed thereover a blanket silicon nitride layer. There is then formed upon the blanket silicon nitride layer a patterned photoresist layer. Finally, there is etched through a plasma etch method while employing the patterned photoresist layer as an etch mask layer the blanket silicon nitride layer to form a patterned silicon nitride layer. The plasma etch method employs an etchant gas composition comprising a perfluorocarbon etchant gas, a hydrofluorocarbon etchant gas and an oxygen etchant gas at a perfluorocarbon etchant gas flow rate, a hydrofluorocarbon etchant gas flow rate and an oxygen etchant gas flow rate which yields substantially no plasma etch bias of the patterned silicon nitride layer with respect to the patterned photoresist layer. When the patterned silicon nitride layer is employed within a thermal oxidation mask, the blanket silicon nitride layer is only nearly completely patterned through the plasma etch method. The nearly completely patterned silicon nitride layer is then completely patterned and over-etched through a second plasma etch method, where the second plasma etch method employs a second etchant gas composition comprising a perfluorocarbon etchant gas, a hydrofluorocarbon etchant gas and an oxygen etchant gas at a perfluorocarbon etchant gas flow rate, a hydrofluorocarbon etchant gas flow rate and an oxygen etchant gas flow rate which minimizes etching of a blanket silicon oxide layer formed beneath the patterned silicon nitride layer within the thermal oxidation mask.
Inventors
- 👤 Ching-Ying Lee
- 👤 Kuo-Chang Wu
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-03 21:34
CPC Classifications
H; H10; H10P; H10P50/00; H10P50/20; H10P50/28; H10P50/282; H10P50/283
Claims Analysis
Total Claims: 11
Claim 1
Independent Claim
268 words
A plasma etch method for forming a patterned silicon nitride layer upon a blanket silicon oxide layer within an integrated circuit comprising: providing a substrate; forming over the substrate a blanket silicon oxide layer; forming upon the blanket silicon oxide layer a blanket silicon nitride layer; forming upon the blanket silicon nitride layer a pattered photoresist layer; etching the blanket silicon nitride layer through use of a first plasma etch method while employing the patterned photoresist layer as an etch mask layer to form a nearly completely etched patterned silicon nitride layer, the first plasma etch method comprising a first etchant gas composition comprising a perfluorocarbon etchant gas, a hydrofluorocarbon etchant gas and an oxygen etchant gas at a perfluorocarbon etchant gas flow rate, a hydrofluorocarbon etchant gas flow rate and an oxygen etchant gas flow rate which yields substantially no plasma etch bias of the nearly completely etched patterned silicon nitride layer with respect to the pattered photoresist layer; and completely etching the nearly completely etched patterned silicon nitride layer through use of a second plasma etch method while employing the patterned photoresist layer as an etch mask layer to form a completely etched patterned silicon nitride layer, the second plasma etch method comprising a second etching gas composition comprising a perfluorocarbon etchant gas, a hydrofluorocarbon etchant gas and an oxygen etchant gas at a perfluorocarbon etchant gas flow rate, a hydrofluorocarbon etchant gas flow rate and an oxygen etchant gas flow rate which minimizes etching of the blanket silicon oxide layer, where the second etchant gas composition is not equivalent to the first etchant gas composition.
Claim 2
Dependent Claim
268 words
A plasma etch method for forming a patterned silicon nitride layer upon a blanket silicon oxide layer within an integrated circuit comprising: providing a substrate; forming over the substrate a blanket silicon oxide layer; forming upon the blanket silicon oxide layer a blanket silicon nitride layer; forming upon the blanket silicon nitride layer a pattered photoresist layer; etching the blanket silicon nitride layer through use of a first plasma etch method while employing the patterned photoresist layer as an etch mask layer to form a nearly completely etched patterned silicon nitride layer, the first plasma etch method comprising a first etchant gas composition comprising a perfluorocarbon etchant gas, a hydrofluorocarbon etchant gas and an oxygen etchant gas at a perfluorocarbon etchant gas flow rate, a hydrofluorocarbon etchant gas flow rate and an oxygen etchant gas flow rate which yields substantially no plasma etch bias of the nearly completely etched patterned silicon nitride layer with respect to the pattered photoresist layer; and completely etching the nearly completely etched patterned silicon nitride layer through use of a second plasma etch method while employing the patterned photoresist layer as an etch mask layer to form a completely etched patterned silicon nitride layer, the second plasma etch method comprising a second etching gas composition comprising a perfluorocarbon etchant gas, a hydrofluorocarbon etchant gas and an oxygen etchant gas at a perfluorocarbon etchant gas flow rate, a hydrofluorocarbon etchant gas flow rate and an oxygen etchant gas flow rate which minimizes etching of the blanket silicon oxide layer, where the second etchant gas composition is not equivalent to the first etchant gas composition.
Claim 3
Dependent Claim
20 words
The method of claim 1 wherein the blanket silicon oxide layer is from about 200 to about 350 angstroms thick.
Claim 4
Dependent Claim
20 words
The method of claim 1 wherein the blanket silicon nitride layer is from about 1000 to about 2000 angstroms thick.
Claim 5
Dependent Claim
21 words
The method of claim 1 wherein the patterned photoresist layer has linewidth and pitch dimensions of less than about 0.5 microns.
Claim 6
Dependent Claim
18 words
The method of claim 1 wherein the perfluorocarbon gas is carbon tetrafluoride and the hydrofluorocarbon gas is trifluoromethane.
Claim 7
Dependent Claim
35 words
The method of claim 1 wherein a second oxygen etchant gas volume concentration within the second etchant gas composition is eater than a first oxygen etchant gas volume concentration within the first etchant gas composition.
Claim 8
Dependent Claim
141 words
The method of claim 5 wherein: within the first plasma etch method the carbon tetrafluoride perfluorocarbon etchant gas flow rate is from about 10 to about 50 standard cubic centimeters per minute (sccm), the trifluoromethane hydrofluorocarbon etchant gas flow rate is from about 10 to about 50 standard cubic centimeters per minute (sccm) and the oxygen etchant gas flow rate is from about 1 to about 30 standard cubic centimeters per minute (sccm); and within the second plasma etch method the carbon tetrafluoride perfluorocarbon etchant gas flow rate is from about 10 to about 50 standard cubic centimeters per minute (sccm), the trifluoromethane hydrofluorocarbon etchant gas flow rate is from about 10 to about 50 standard cubic centimeters per minute (sccm) and the oxygen etchant gas flow rate is from about 30 to about 70 standard cubic centimeters per minute (sccm).
Claim 9
Dependent Claim
33 words
The method of claim 7 further comprising a background gas within the first etchant gas composition, the background gas being present at a flow rate of about 800 standard cubic centimeters per minute.
Claim 10
Dependent Claim
141 words
The method of claim 5 wherein: within the first plasma etch method the carbon tetrafluoride perfluorocarbon etchant gas flow rate is from about 10 to about 50 standard cubic centimeters per minute (sccm), the trifluoromethane hydrofluorocarbon etchant gas flow rate is from about 20 to about 30 standard cubic centimeters per minute (sccm) and the oxygen etchant gas flow rate is from about 6 to about 15 standard cubic centimeters per minute (sccm); and within the second plasma etch method the carbon tetrafluoride perfluorocarbon etchant gas flow rate is from about 10 to about 50 standard cubic centimeters per minute (sccm), the trifluoromethane hydrofluorocarbon etchant gas flow rate is from about 15 to about 25 standard cubic centimeters per minute (sccm) and the oxygen etchant gas flow rate is from about 40 to about 60 standard cubic centimeters per minute (sccm).
Claim 11
Dependent Claim
33 words
The method of claim 9 further comprising a background gas within the first etchant gas composition, the background gas being present at a flow rate of about 800 standard cubic centimeters per minute.
References Cited (Backward Citations)
USRE30505E
Cited
US4180432A
Cited
US4484979A
Cited
US4978420A
Cited
JPH0521795A
Cited
JPH05160077A
Cited
JPH05217954A
Cited
US5700739A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 2002-07-12 | 2003-01-11 | 2003-07-13 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2006-07-12 | 2007-01-11 | 2007-07-13 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2010-07-12 | 2011-01-11 | 2011-07-13 | $7700.00 | Window Closed / Lapsed |