US5385633A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Method for laser-assisted silicon etching using halocarbon ambients
Assignee: United States Department of the Navy
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Filing: 1990-03-29
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Granted: 1995-01-31
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Expires: 2010-03-29
Abstract
Abstract An etching process allows a selective single-step patterning of silicon devices in a noncorrosive environment. The etching of silicon relies on a maskless laser-assisted technique in a gaseous halocarbon ambient, such as the gaseous chlorofluorocarbons, dichlorodifluoromethane and chloropentafluoroethane. Laser-assisted photothermal chemical etching reactions on silicon occur in these ambients when the incident fluence from an excimer laser at 248 nm exceeds the melt threshold (approximately 0.75 J/cm2). When incident fluence exceeds the ablation threshold (approximately 2.2 J/cm2) an undesirable, increased surface roughness is observed. Etch rates as large as approximately 15 angstroms per pulse are attained within predetermined processing windows. This provides a means for thin membrane formation in silicon, rapid etches and processing of packaged devices or partially fabricated dies. The reduction in processing steps as compared to conventional wet chemical etches provides improvements in yield, reliability and cost.
Inventors
- 👤 Stephen D. Russell
- 👤 Douglas A. Sexton
- 👤 Richard J. Orazi
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-09 03:13
CPC Classifications
B; B01; B01D; B01D53/00; B01D53/007; B01J; B01J19/00; B01J19/08; B01J19/12; B01J19/121; H; H10; H10F; H10F77/00; H10F77/70; H10F77/703; H10P; H10P50/00; H10P50/20; H10P50/24; H10P50/242; Y; Y02; Y02E; Y02E10/00; Y02E10/50
Claims Analysis
Total Claims: 14
Claim 1
Independent Claim
72 words
A method of performing a maskless laser-assisted etching of silicon in a gaseous chlorofluorocarbon ambient comprising: placing said silicon in contact with said gaseous chlorofluorocarbon ambient; directing radiant energy onto said silicon within said gaseous chlorofluorocarbon ambient to create a melted portion of said silicon where the radiant energy impinges; and etching away only said melted portion of said silicon within said gaseous chlorofluorocarbon ambient which have said radiant energy impinging thereon.
Claim 2
Independent Claim
72 words
A method of performing a maskless laser-assisted etching of silicon in a gaseous chlorofluorocarbon ambient comprising: placing said silicon in contact with said gaseous chlorofluorocarbon ambient; directing radiant energy onto said silicon within said gaseous chlorofluorocarbon ambient to create a melted portion of said silicon where the radiant energy impinges; and etching away only said melted portion of said silicon within said gaseous chlorofluorocarbon ambient which have said radiant energy impinging thereon.
Claim 3
Dependent Claim
20 words
A method according to claim 1 in which said radiant energy is a UV wavelength beam coming from a laser.
Claim 4
Dependent Claim
48 words
A method according to claim 2 in which said silicon sample is placed within a processing chamber and said chlorofluorocarbon ambient is pressurized within predetermined limits and said UV wavelength beam is at predetermined rates and intensities to assure that said silicon is melted but not ablated thereby.
Claim 5
Dependent Claim
28 words
A method according to claim 3 in which said UV wavelength beam is shaped, homogenized and adjusted in magnitude to obtain an optimal fluence impinging onto said silicon.
Claim 6
Dependent Claim
19 words
A method according to claim 4 in which the pressure of said ambient chlorofluorocarbon is greater than 150 torr.
Claim 7
Dependent Claim
39 words
A method according to claim 5 in which the pressure of said ambient chlorofluorocarbon is between 600 and 900 torr and the incident fluence of said UV wavelength beam is between 0.75 J/cm 2 and 2.0 J/cm 2 .
Claim 8
Dependent Claim
15 words
A method according to claim 5 or 6 in which the chlorofluorocarbon ambient is chloropentafluoroethane.
Claim 9
Dependent Claim
15 words
A method according to claim 5 or 6 in which the chlorofluorocarbon ambient is dichlorodifluoromethane.
Claim 10
Independent Claim
72 words
A method of performing a maskless laser-assisted etching of silicon in a gaseous halocarbon ambient comprising: placing said silicon in contact with said gaseous halocarbon ambient; directing radiant energy onto said silicon within said gaseous halocarbon ambient to create a melted portion of said silicon where the radiant energy impinges; and etching away only said melted portion of said silicon within said gaseous halocarbon ambient which have said radiant energy impinging thereon.
Claim 11
Independent Claim
72 words
A method of performing a maskless laser-assisted etching of silicon in a gaseous halocarbon ambient comprising: placing said silicon in contact with said gaseous halocarbon ambient; directing radiant energy onto said silicon within said gaseous halocarbon ambient to create a melted portion of said silicon where the radiant energy impinges; and etching away only said melted portion of said silicon within said gaseous halocarbon ambient which have said radiant energy impinging thereon.
Claim 12
Dependent Claim
20 words
A method according to claim 9 in which said radiant energy is a UV wavelength beam coming from a laser.
Claim 13
Dependent Claim
48 words
A method according to claim 10 in which said silicon sample is placed within a processing chamber and said halocarbon ambient is pressurized within predetermined limits and said UV wavelength beam is at predetermined rates and intensities to assure that said silicon is melted but not ablated thereby.
Claim 14
Dependent Claim
18 words
A method according to claim 11 in which the UV wavelength beam is emitted from an excimer laser.
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) | 1998-01-30 | 1998-08-01 | 1999-01-31 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2002-01-30 | 2002-08-01 | 2003-01-31 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2006-01-30 | 2006-08-01 | 2007-01-31 | $7700.00 | Window Closed / Lapsed |