US4973379A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Method of aerosol jet etching
Assignee: The University of Texas System
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Filing: 1988-12-21
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Granted: 1990-11-27
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Expires: 2008-12-21
Abstract
Abstract A device and method for etching a body are provided capable of etching fine geometry patterns utilizing the high selectivity of wet etching and the anisotropic etch characteristics of dry etching. The body to be etched is placed in a reduced pressure etching chamber. An inert carrier gas is bubbled through heated liquid etchant producing a vapor stream of liquid etchant. A non-reactive gas is chilled producing a cold gas stream. The vapor stream and the cold gas stream are combined in an aerosol generation nozzle producing a high concentration of fine aerosol particles by homogeneous nucleation. The fine aerosol particles enter an aerosol growth chamber and form larger particles through thermal coagulation. The larger particles are accelerated out of the growth chamber through an expansion nozzle positioned within the reduced pressure etching chamber and directed toward the body to be etched. This aerosol jet of etchant impacts the surface of the body to be etched. The small size of these larger particles allows for etching fine geometry patterns. Additionally, aerosol jet etching avoids the need to rinse the body after being etched as required in wet etching to halt the etching process.
Inventors
- 👤 James R. Brock
- 👤 Isaac Trachtenberg
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-06 13:05
CPC Classifications
C; C23; C23F; C23F1/00; C23F1/08; C23F1/10; C23F1/12
Claims Analysis
Total Claims: 34
Claim 1
Independent Claim
80 words
A method of etching a substrate comprising: generating an etchant vapor; combining said etchant vapor with a cold non-reactive gas to produce a high concentration of fine aerosol particles of etchant; confining said fine aerosol particles to form larger particles; directing said larger particles onto a substrate mounted in an etching chamber having a reduced pressure atmosphere, said substrate being maintained at a temperature high enough to prevent etchant film formation; and, allowing said larger particles to etch said substrate.
Claim 2
Independent Claim
80 words
A method of etching a substrate comprising: generating an etchant vapor; combining said etchant vapor with a cold non-reactive gas to produce a high concentration of fine aerosol particles of etchant; confining said fine aerosol particles to form larger particles; directing said larger particles onto a substrate mounted in an etching chamber having a reduced pressure atmosphere, said substrate being maintained at a temperature high enough to prevent etchant film formation; and, allowing said larger particles to etch said substrate.
Claim 3
Dependent Claim
16 words
The method of claim 1 wherein said reduced pressure atmosphere is from 0.1 to 400 torr.
Claim 4
Dependent Claim
23 words
The method of claim 1 wherein the substrate is maintained at a temperature low enough to preclude formation of an etchant vapor barrier.
Claim 5
Dependent Claim
24 words
The method of claim 1 wherein said step of generating said etchant vapor comprises bubbling a particle-free non-reactive carrier gas through a liquid etchant.
Claim 6
Dependent Claim
24 words
The method of claim 4 wherein said carrier gas is at least one gas selected from the group consisting of nitrogen, helium and argon.
Claim 7
Dependent Claim
18 words
The method of claim 4 further comprising the step of maintaining said liquid etchant at a constant temperatures.
Claim 8
Dependent Claim
30 words
The method of claim 4 wherein immediately after the step of generating said etchant vapor, said etchant vapor is maintained at a temperature sufficient to minimize condensation of said vapor.
Claim 9
Dependent Claim
13 words
The method of claim 4 wherein said liquid etchant is volatilizable and recondensable.
Claim 10
Dependent Claim
12 words
The method of claim 4 wherein said liquid etchant is an azeotrope.
Claim 11
Dependent Claim
18 words
The method of claim 4 wherein said etchant comprises hydrofluoric acid and wherein said substrate is silicon dioxide.
Claim 12
Dependent Claim
26 words
The method of claim 4 wherein said etchant is selected from the group consisting of bromine-methanol and hydrochloric acid and wherein said substrate is gallium arsenide.
Claim 13
Dependent Claim
30 words
The method of claim 1 wherein immediately after the step of generating said etchant vapor, said etchant vapor is maintained at a temperature sufficient to minimize condensation of said vapor.
Claim 14
Dependent Claim
17 words
The method of claim 1 wherein said etchant comprises hydrofluoric acid and said substrate comprises silicon dioxide.
Claim 15
Dependent Claim
26 words
The method of claim 1 wherein said etchant is selected from the group consisting of bromine-methanol and hydrochloric acid and wherein said substrate comprises gallium arsenide.
Claim 16
Dependent Claim
25 words
The method of claim 1 wherein said cold non-reactive gas is at least one gas selected from the group consisting of nitrogen, helium and argon.
Claim 17
Dependent Claim
22 words
The method of claim 15 wherein said cold non-reactive gas is of a temperature less than or equal to about 40° C.
Claim 18
Dependent Claim
22 words
The method of claim 1 wherein said cold non-reactive gas is of a temperature less than or equal to about 40° C.
Claim 19
Dependent Claim
34 words
The method of claim 1 wherein said step of combining said etchant vapor with said cold non-reactive gas occurs in a mixing chamber designed to minimize formation of vapor condensate on interior surfaces thereof.
Claim 20
Dependent Claim
34 words
The method of claim 18 wherein immediately prior to said step of combining said etchant vapor with said cold non-reactive gas and retarding heat transfer between said etchant vapor and said cold non-reactive gas.
Claim 21
Dependent Claim
28 words
The method of claim 1 wherein said step of confining said fine aerosol particles includes colliding, adhering and growing said fine aerosol particles to form said larger particles.
Claim 22
Dependent Claim
20 words
The method of claim 1 wherein said step of confining said fine aerosol particles occurs in an aerosol growth chamber.
Claim 23
Dependent Claim
27 words
The method of claim 21 further defined wherein said aerosol growth chamber is designed to minimize heat transfer between said etching chamber and said aerosol growth chamber.
Claim 24
Independent Claim
24 words
The method of claim wherein said step of directing said larger particles onto said substrate comprises accelerating said larger particles through an expansion nozzle.
Claim 25
Dependent Claim
23 words
The method of claim 23 wherein said larger particles are accelerated to velocities in the range of 150 to 350 meters per second.
Claim 26
Dependent Claim
27 words
The method of claim 23 wherein said step of directing said larger particles further comprises positioning said expansion nozzle about 2 to 5 centimeters from said substrate.
Claim 27
Dependent Claim
17 words
The method of claim 1 wherein said larger particles are from 0.05 to 0.2 microns in diameter.
Claim 28
Dependent Claim
16 words
The method of claim 1 wherein etching depth on said substrate per unit of time decreases.
Claim 29
Dependent Claim
14 words
The method of claim 1 wherein said substrate to be etched is silicon dioxide.
Claim 30
Independent Claim
114 words
A method of etching a substrate comprising: generating an etchant vapor; maintaining said etchant vapor at a temperature to minimize condensation; combining said etchant vapor in a mixing chamber with a cold non-reactive gas to produce fine aerosol particles of etchant; confining said fine aerosol particles in an aerosol growth chamber to form larger particles having diameters of between about 0.05 and about 0.2 microns; directing said larger particles through an expansion nozzle and into an etching chamber having a reduced pressure atmosphere toward and onto a substrate mounted therein; allowing said larger etchant particles to etch said substrate; and controlling etching depth on said substrate by maintaining said substrate at a selected temperature.
Claim 31
Independent Claim
114 words
A method of etching a substrate comprising: generating an etchant vapor; maintaining said etchant vapor at a temperature to minimize condensation; combining said etchant vapor in a mixing chamber with a cold non-reactive gas to produce fine aerosol particles of etchant; confining said fine aerosol particles in an aerosol growth chamber to form larger particles having diameters of between about 0.05 and about 0.2 microns; directing said larger particles through an expansion nozzle and into an etching chamber having a reduced pressure atmosphere toward and onto a substrate mounted therein; allowing said larger etchant particles to etch said substrate; and controlling etching depth on said substrate by maintaining said substrate at a selected temperature.
Claim 32
Dependent Claim
17 words
The method of claim 29 wherein the expansion nozzle has a diameter of 0.2 to 1.2 millimeters.
Claim 33
Dependent Claim
26 words
The method of claim 29 wherein the larger particles are diverted into the etching chamber at a velocity of from 150 to 350 meters per second.
Claim 34
Dependent Claim
34 words
The method of claim 29 wherein the substrate is maintained at a temperature low enough to preclude formation of an etchant vapor barrier and high enough to preclude formation of a liquid etchant film.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1993-11-26 | 1994-05-28 | 1994-11-27 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1997-11-26 | 1998-05-28 | 1998-11-27 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2001-11-26 | 2002-05-28 | 2002-11-27 | $7700.00 | Window Closed / Lapsed |