US5420078A
Expired / Lapsed
US
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Method for producing via holes in integrated circuit layers
Assignee: Philips Semiconductors Inc
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Filing: 1994-07-19
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Granted: 1995-05-30
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Expires: 2014-07-19
Abstract
Abstract A method for forming via holes characterized by an isotropic etch of a dielectric surface through a mask opening by means of an acidic vapor, followed by an anisotropic etch through mask openings into the body of the dielectric surface. Preferably, the acidic vapor comprises hydrofluoric (HF) acid and a nitrogen (N 2 ) carrier gas. The isotropic etch step undercuts the mask around the mask openings to form tapered recesses which subsequently become tapered via hole rims after the anisotropic etch step.
Inventors
- 👤 Robert M. Sikora
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-06 08:46
CPC Classifications
H; H10; H10W; H10W20/00; H10W20/01; H10W20/071; H10W20/081; H10W20/082
Claims Analysis
Total Claims: 25
Claim 1
Independent Claim
119 words
A method for forming a tapered via hole in an integrated circuit layer comprising the steps of: covering a surface to be etched with a mask having at least one opening, said opening having an opening diameter of at most 0.8 microns; isotropically etching said surface through said opening with an acid vapor supplied at a flow rate that is not conducive to condensation of the acid vapor on the surface to provide a tapered recess in said surface that has a maximum diameter greater than said opening diameter; and anisotropically etching said surface through said opening and said tapered recess to form a via hole which has a diameter that is about the same as said opening diameter.
Claim 2
Independent Claim
119 words
A method for forming a tapered via hole in an integrated circuit layer comprising the steps of: covering a surface to be etched with a mask having at least one opening, said opening having an opening diameter of at most 0.8 microns; isotropically etching said surface through said opening with an acid vapor supplied at a flow rate that is not conducive to condensation of the acid vapor on the surface to provide a tapered recess in said surface that has a maximum diameter greater than said opening diameter; and anisotropically etching said surface through said opening and said tapered recess to form a via hole which has a diameter that is about the same as said opening diameter.
Claim 3
Dependent Claim
13 words
A method as recited in claim 1 wherein said acid vapor comprises HF.
Claim 4
Dependent Claim
17 words
A method as recited in claim 2 wherein said acid vapor further comprises an inert carrier gas.
Claim 5
Dependent Claim
14 words
A method as recited in claim 3 wherein said inert carrier gas is nitrogen.
Claim 6
Dependent Claim
34 words
A method as recited in claim 2 wherein said acid vapor of HF is caused to flow past said surface at a rate in the range of about 0.01 liter/minute to about 1 liter/minute.
Claim 7
Dependent Claim
29 words
A method as recited in claim 5 wherein said acid vapor of HF is caused to flow past said surface at a rate of about 0.1 liter per minute.
Claim 8
Dependent Claim
31 words
A method as recited in claim 4 wherein said nitrogen is caused to flow past said surface at a rate in the range of about 1 liter/minute to about 30 liters/minute.
Claim 9
Dependent Claim
24 words
A method as recited in claim 7 wherein said nitrogen is cause to flow past said surface at a rate of about 8 liters/minute.
Claim 10
Dependent Claim
34 words
A method as recited in claim 7 wherein said acid vapor of HF is caused to flow past said surface at a rate in the range of about 0.01 liter/minute to about 1 liter/minute.
Claim 11
Dependent Claim
26 words
A method as recited in claim 7 wherein said acid vapor of HF and said carrier gas of nitrogen are at approximately ambient temperature and pressure.
Claim 12
Independent Claim
135 words
A method for forming a via in an integrated circuit layer comprising the steps of: covering a surface to be etched with a mask having at least one opening, said opening having an opening diameter of at most 0.8 microns; isotropically etching said surface through said opening with an acid vapor supplied at a flow rate that is not conducive to condensation of the acid vapor on the surface to provide a tapered recess in said surface that has a maximum diameter greater than said opening diameter; anisotropically etching said surface through said opening and said tapered recess to form a via hole which has a diameter that is about the same as said opening diameter; removing said mask from said surface; and depositing a conductive material over said surface and within said via hole.
Claim 13
Independent Claim
135 words
A method for forming a via in an integrated circuit layer comprising the steps of: covering a surface to be etched with a mask having at least one opening, said opening having an opening diameter of at most 0.8 microns; isotropically etching said surface through said opening with an acid vapor supplied at a flow rate that is not conducive to condensation of the acid vapor on the surface to provide a tapered recess in said surface that has a maximum diameter greater than said opening diameter; anisotropically etching said surface through said opening and said tapered recess to form a via hole which has a diameter that is about the same as said opening diameter; removing said mask from said surface; and depositing a conductive material over said surface and within said via hole.
Claim 14
Dependent Claim
19 words
A method as recited in claim 11 wherein said acid vapor comprises an HF vapor and a carrier gas.
Claim 15
Dependent Claim
57 words
A method as recited in claim 12 wherein said HF is caused to flow past said surface at a rate in the range of about 0.01 liter/minute to about 1 liter/minute and wherein said carrier gas is caused to flow past said surface at a rate in the range of about 1 liter/minute to about 30 liters/minute.
Claim 16
Dependent Claim
22 words
A method as recited in claim 13 wherein said HF vapor and said carrier gas are at about ambient pressures and temperatures.
Claim 17
Dependent Claim
13 words
A method as recited in claim 12 wherein said carrier gas comprises nitrogen.
Claim 18
Independent Claim
163 words
A method for forming a via substantially without cusps and voids in an integrated circuit layer comprising the steps of: covering a surface to be etched with a mask having at least one opening, said opening having an opening diameter of at most 0.8 microns; isotropically etching said surface through said opening with vapor comprising HF, said vapor being supplied at a flow rate that is not conducive to condensation of the vapor on the surface and carried by a nitrogen carrier, to provide a tapered recess in said surface that has a maximum diameter greater than said opening diameter; anisotropically etching said surface through said opening and said tapered recess to form a via hole which has a diameter that is about the same as said opening diameter; removing said mask from said surface; and depositing a conductive material over said surface and within said via hole to substantially fill said via hole and provide said via substantially without cusps and voids.
Claim 19
Independent Claim
163 words
A method for forming a via substantially without cusps and voids in an integrated circuit layer comprising the steps of: covering a surface to be etched with a mask having at least one opening, said opening having an opening diameter of at most 0.8 microns; isotropically etching said surface through said opening with vapor comprising HF, said vapor being supplied at a flow rate that is not conducive to condensation of the vapor on the surface and carried by a nitrogen carrier, to provide a tapered recess in said surface that has a maximum diameter greater than said opening diameter; anisotropically etching said surface through said opening and said tapered recess to form a via hole which has a diameter that is about the same as said opening diameter; removing said mask from said surface; and depositing a conductive material over said surface and within said via hole to substantially fill said via hole and provide said via substantially without cusps and voids.
Claim 20
Dependent Claim
31 words
A method as recited in claim 16 wherein said vapor is caused to flow past said surface at a rate in the range of about 0.01 liter/minute to about 1 liter/minute.
Claim 21
Dependent Claim
26 words
A method as recited in claim 16 wherein said vapor is caused to flow past said surface at a rate of about 0.1 liter per minute.
Claim 22
Dependent Claim
31 words
A method as recited in claim 17 wherein said nitrogen is caused to flow past said surface at a rate in the range of about 1 liter/minute to about 30 liters/minute.
Claim 23
Dependent Claim
24 words
A method as recited in claim 17 wherein said nitrogen is cause to flow past said surface at a rate of about 8 liters/minute.
Claim 24
Dependent Claim
20 words
A method as recited in claim 17 wherein said vapor and said nitrogen are at approximately ambient temperature and pressure.
Claim 25
Dependent Claim
34 words
A method as recited in claim 16 wherein said step of isotropically etching is accomplished at an etch rate in the range of about 300 angstroms per minute to about 12,000 angstroms per minute.
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) | 1998-05-29 | 1998-11-28 | 1999-05-30 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2002-05-29 | 2002-11-28 | 2003-05-30 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2006-05-29 | 2006-11-28 | 2007-05-30 | $7700.00 | Window Closed / Lapsed |