US4685996A
Expired / Lapsed
US
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Method of making micromachined refractory metal field emitters
Assignee: Individual
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Filing: 1986-10-14
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Granted: 1987-08-11
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Expires: 2006-10-14
Abstract
Abstract A method of making a field emitter includes anisotropically etching a single crystal silicon substrate to form at least one funnel-shaped protrusion on the substrate, then conformally depositing a refractory metal onto the funnel-shaped protrusion. Alternatively, single crystal silicon may be anisotropically etched to form at least one funnel-shaped recess in the silicon. The etched surface is doped with an impurity to form an etch-stop layer, the remaining undoped silicon is removed, then the etch-stop layer is conformally deposited with a refractory metal. The funnel-shaped recess can then be back-filled with silicon or another suitable material.
Inventors
- 👤 Heinz H. Busta
- 👤 Raul D. Cuellar
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-24 16:18
CPC Classifications
H; H01; H01J; H01J9/00; H01J9/02; H01J9/022; H01J9/025; H10; H10P; H10P50/00; H10P50/60; H10P50/64; H10P50/642; H10P50/644; B; B82; B82Y; B82Y35/00; Y; Y10; Y10S; Y10S438/00; Y10S438/914; Y10S438/924; Y10S438/928
Claims Analysis
Total Claims: 21
Claim 1
Independent Claim
94 words
A method of making a field-emitter structure comprising the steps of: (a) providing a substrate of single crystal silicon having a front surface and a back surface; (b) etching the front surface of the substrate to form at least one funnel-shaped recess in the substrate; (c) diffusing an impurity into the etched substrate front surface to form an etch-stop layer; (d) etching the back surface of the substrate to remove the single crystal silicon down to the etch-stop layer; and (e) conformally depositing a refractory metal onto the etched back surface of the substrate.
Claim 2
Independent Claim
94 words
A method of making a field-emitter structure comprising the steps of: (a) providing a substrate of single crystal silicon having a front surface and a back surface; (b) etching the front surface of the substrate to form at least one funnel-shaped recess in the substrate; (c) diffusing an impurity into the etched substrate front surface to form an etch-stop layer; (d) etching the back surface of the substrate to remove the single crystal silicon down to the etch-stop layer; and (e) conformally depositing a refractory metal onto the etched back surface of the substrate.
Claim 3
Dependent Claim
58 words
The method of claim 1 wherein step (b) comprises the steps of: selectively masking the front surface of the substrate such that an unmasked area defines at least one island on the front surface; orientation-dependent etching the single crystal silicon under the unmasked area to form at least one funnel-shaped recess in the substrate; and removing the mask.
Claim 4
Dependent Claim
17 words
The method of claim 2 wherein said orientation-dependent etching is accomplished in a solution of ethylenediamine-pyrocatechol-water (EPW).
Claim 5
Dependent Claim
13 words
The method of claim 3 wherein said etch-stop layer is formed by boron-doping.
Claim 6
Dependent Claim
32 words
The method of claim 4 wherein said conformal deposition is accomplished by chemical-vapor deposition according to the reaction: 2MF.sub.6 +3Si→2M+3SiF.sub.4, where M is selected from the group consisting of tungsten and molybdenum.
Claim 7
Dependent Claim
10 words
The method of claim 5 wherein said metal is tungsten.
Claim 8
Dependent Claim
10 words
The method of claim 5 wherein said metal is molybdenum.
Claim 9
Dependent Claim
10 words
The method of claim 3 wherein said solution is KOH.
Claim 10
Dependent Claim
21 words
The method of claim 1 further comprising the step of: (f) filling the funnel-shaped recess in the substrate with a material.
Claim 11
Independent Claim
60 words
A method of making a field-emitter structure comprising the steps of: (a) providing a substrate of single crystal silicon having a front surface and a back surface; (b) etching the front surface of the substrate to form at least one funnel-shaped protrusion on the substrate; and (c) conformally depositing a refractory metal onto the etched front surface of the substrate.
Claim 12
Independent Claim
60 words
A method of making a field-emitter structure comprising the steps of: (a) providing a substrate of single crystal silicon having a front surface and a back surface; (b) etching the front surface of the substrate to form at least one funnel-shaped protrusion on the substrate; and (c) conformally depositing a refractory metal onto the etched front surface of the substrate.
Claim 13
Dependent Claim
61 words
The method of claim 10 wherein step (b) comprises the steps of: selectively masking the front surface of the substrate such that a masked area defines at least one island on the front surface of the substrate; orientation-dependent etching the single crystal silicon under the masked area to form at least one funnel-shaped protrusion in the substrate; and removing the mask.
Claim 14
Dependent Claim
17 words
The method of claim 11 wherein said oxidation-dependent etching is accomplished in a solution of ethylenediamine-pyrocatechol-water (EPW).
Claim 15
Dependent Claim
13 words
The method of claim 12 wherein said mask is formed of silicon dioxide.
Claim 16
Dependent Claim
32 words
The method of claim 13 wherein said selective deposition is accomplished by chemical-vapor deposition according to the reaction 2MF.sub.6 +3Si→2M+3SiF.sub.4, where M is selected from the group consisting of tungsten and molybdenum.
Claim 17
Dependent Claim
10 words
The method of claim 14 wherein said metal is tungsten.
Claim 18
Dependent Claim
10 words
The method of claim 14 wherein said metal is molybdenum.
Claim 19
Dependent Claim
10 words
The method of claim 12 wherein said solution is KOH.
Claim 20
Dependent Claim
30 words
The method of claim 5 further comprising the step of: (f) depositing a refractory metal onto the etched back surface of the substrate according to the reaction: MF.sub.6 +3H.sub.2 →M+6HF.
Claim 21
Dependent Claim
29 words
The method of claim 14 further comprising the step of: (d) depositing a refractory metal onto the etched front of the substrate according to the reaction: MF.sub.6 +3H.sub.2 →M+6HF.
References Cited (Backward Citations)
US3746587A
Cited
US4171234A
Cited
US4371803A
Cited
US4428111A
Cited
US4396459A
Cited
US4618397A
Cited
US4614119A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1990-08-10 | 1991-02-09 | 1991-08-11 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1994-08-10 | 1995-02-09 | 1995-08-11 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1998-08-10 | 1999-02-09 | 1999-08-11 | $7700.00 | Window Closed / Lapsed |