Patent US4765865A successfully refreshed from Google Patents.
US4765865A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Silicon etch rate enhancement
Assignee: Ford Motor Co
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Filing: 1987-05-04
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Granted: 1988-08-23
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Expires: 2007-05-04
Abstract
Abstract This invention is directed to a method for increasing the etch rate of a single crystal silicon wafer in an anisotropic etching solution. This method comprises applying a mask material to a portion of one face of the wafer and a metal coating to substantially the entire surface of an opposite face of the wafer which renders the electrode potential of the masked, metal coated single crystal silicon wafer more anodic than that of a masked, single crystal silicon wafer alone, and exposing the coated wafer to a suitable anisotropic etching solution. This method may further comprise applying an external anodic voltage to the masked, metal coated single crystal silicon wafer, which voltage is less than that which causes the electrode potential of the masked, metal coated single crystal silicon wafer to exceed the passivation potential of the masked, single crystal silicon wafer.
Inventors
- 👤 Roy L. Gealer
- 👤 Hans K. Karsten
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-26 05:29
CPC Classifications
H; H10; H10P; H10P50/00; H10P50/60; H10P50/61; H10P50/613; H10P50/64; H10P50/642; H10P50/644; Y; Y10; Y10T; Y10T428/00; Y10T428/12; Y10T428/12493; Y10T428/12528; Y10T428/24; Y10T428/24273; Y10T428/24322; Y10T428/24331
Claims Analysis
Total Claims: 30
Claim 1
Independent Claim
188 words
A method for etching a first face of a single crystal silicon wafer in an anisotropic etching solution, said wafer having a second face opposite said first face, which method comprises: providing a mask material to a portion of said first face of said single crystal silicon wafer in a predetermined pattern which exposes a region of said first face to be etched; applying a metal coating to substantially the entire surface of said second face of said single crystal silicon wafer, said metal coating being (a) in electrical contact with said second face of said crystal silicon wafer and (b) selected from metals which (i) are substantially resistant to attack by said anisotropic etching solution and (ii) render the electrode potential of the masked, metal coated single crystal silicon wafer, in said anisotropic etching solution, more anodic than that of said masked, single crystal silicon wafer alone; and exposing said masked, metal coated single crystal silicon wafer to said anisotropic etching solution for a time necessary to etch, to a desired depth, said region of said first face of said masked, metal coated single crystal silicon wafer.
Claim 2
Independent Claim
188 words
A method for etching a first face of a single crystal silicon wafer in an anisotropic etching solution, said wafer having a second face opposite said first face, which method comprises: providing a mask material to a portion of said first face of said single crystal silicon wafer in a predetermined pattern which exposes a region of said first face to be etched; applying a metal coating to substantially the entire surface of said second face of said single crystal silicon wafer, said metal coating being (a) in electrical contact with said second face of said crystal silicon wafer and (b) selected from metals which (i) are substantially resistant to attack by said anisotropic etching solution and (ii) render the electrode potential of the masked, metal coated single crystal silicon wafer, in said anisotropic etching solution, more anodic than that of said masked, single crystal silicon wafer alone; and exposing said masked, metal coated single crystal silicon wafer to said anisotropic etching solution for a time necessary to etch, to a desired depth, said region of said first face of said masked, metal coated single crystal silicon wafer.
Claim 3
Dependent Claim
18 words
A method according to claim 1, wherein said metals are selected from gold, silver, platinum, palladium and nickel.
Claim 4
Dependent Claim
20 words
A method according to claim 1, wherein said mask material is selected from silicon dioxide, silicon nitride, chromium and gold.
Claim 5
Dependent Claim
39 words
A method according to claim 1, wherein said anisotropic etching solution is selected from aqueous sodium hydroxide, aqueous potassium hydroxide, tetramethyl ammonium hydroxide, aqueous phenols capable of etching silicon, aqueous amines capable of etching silicon, and compatible mixtures thereof.
Claim 6
Dependent Claim
15 words
A method according to claim 4, wherein said amines are selected from ethylenediamine and hydrazine.
Claim 7
Dependent Claim
26 words
A method according to claim 5, wherein said anisotropic etching solution comprises ethylenediamine, pyrocatechol, and water in a ratio of about 1 ml:0-0.06 g:0.08-2 ml .
Claim 8
Dependent Claim
35 words
A method according to claim 1, wherein said metal coating is applied to said second face of said single crystal silicon wafer by methods selected from vacuum evaporation techniques, vacuum sputtering techniques, and electrodeposition techniques.
Claim 9
Dependent Claim
47 words
A method according to claim 1, which further comprises applying an interlayer between said second face of said single crystal silicon wafer and said metal coating, said interlayer being an electrically conductive material providing adhesion between said second face of said silicon wafer and said metal coating.
Claim 10
Dependent Claim
16 words
A method according to claim 8, wherein said interlayer material is selected from chromium and titanium.
Claim 11
Dependent Claim
40 words
A method according to claim 8, wherein said interlayer material and said metal coating are applied to said second face of said single crystal silicon wafer by methods independently selected from vacuum evaporation techniques, vacuum sputtering techniques, and electrodeposition techniques.
Claim 12
Dependent Claim
55 words
A method according to claim 1, which further comprises applying an external anodic voltage to said masked, metal coated single crystal silicon wafer, said voltage being less than that which causes the electrode potential of said masked, metal coated single crystal silicon wafer to exceed the passivation potential of a masked, single crystal silicon wafer.
Claim 13
Dependent Claim
29 words
A method acording to claim 11, wherein said external voltage is applied to said metal coating on said second face of said masked, metal coated single crystal silicon wafer.
Claim 14
Dependent Claim
137 words
A masked, metal coated single crystal silicon wafer having a first face adapted for etching in an anisotropic etching solution, said silicon wafer comprising: a first face having a non-metal mask material on a portion thereon in a predetermined pattern which exposes a region of said first face to be etched; and a second face, opposite said first face, having a metal coating which (a) is in electrical contact with and (b) coats substantially the entire surface of said second face of said single crystal silicon wafer, said coating being selected from metals which (i) are substantially resistant to attack by said anisotropic etching solution and (ii) render the electrode potential of the masked, metal coated single crystal silicon wafer, in said anisotropic etching solution, more anodic than that of a masked, single crystal silicon wafer alone.
Claim 15
Dependent Claim
137 words
A masked, metal coated single crystal silicon wafer having a first face adapted for etching in an anisotropic etching solution, said silicon wafer comprising: a first face having a non-metal mask material on a portion thereon in a predetermined pattern which exposes a region of said first face to be etched; and a second face, opposite said first face, having a metal coating which (a) is in electrical contact with and (b) coats substantially the entire surface of said second face of said single crystal silicon wafer, said coating being selected from metals which (i) are substantially resistant to attack by said anisotropic etching solution and (ii) render the electrode potential of the masked, metal coated single crystal silicon wafer, in said anisotropic etching solution, more anodic than that of a masked, single crystal silicon wafer alone.
Claim 16
Dependent Claim
19 words
A silicon wafer according to claim 13, wherein said metals are selected from gold, silver, latinum, palladium, and nickel.
Claim 17
Dependent Claim
20 words
A silicon wafer according to claim 13, wherein said non-metal mask material is selected from silicon dioxide and silicon nitride.
Claim 18
Dependent Claim
49 words
A silicon wafer according to claim 13, which further comprises an interlayer between said second face of said single crystal silicon wafer and said metal coating, said interlayer being an electrically conductive material providing adhesion between said second face of said single crystal silicon wafer and said metal coating.
Claim 19
Dependent Claim
17 words
A silicon wafer according to claim 13, wherein said interlayer material is selected from chromium and titanium.
Claim 20
Independent Claim
151 words
A method for forming a single crystal silicon wafer having a first face being adapted for etching in an anisotropic etching solution, which method comprises: providing a non-metal mask material to a portion of said first face of said single crystal silicon wafer in a predetermined pattern which exposes a region of said first face to be etched; and applying a coating of metal to substantially the entire surface of a second face which is opposite said first face of said single crystal silicon wafer, said metal coating being (a) in electrical contact with said second face of said single crystal silicon wafer and (b) selected from metals which (i) are resistant to attack by said anisotropic etching solution and (ii) render the electrode potential of the masked, metal coated single crystal silicon wafer, in said anisotropic etching solution, more anodic than that of a masked single crystal silicone wafer alone.
Claim 21
Independent Claim
151 words
A method for forming a single crystal silicon wafer having a first face being adapted for etching in an anisotropic etching solution, which method comprises: providing a non-metal mask material to a portion of said first face of said single crystal silicon wafer in a predetermined pattern which exposes a region of said first face to be etched; and applying a coating of metal to substantially the entire surface of a second face which is opposite said first face of said single crystal silicon wafer, said metal coating being (a) in electrical contact with said second face of said single crystal silicon wafer and (b) selected from metals which (i) are resistant to attack by said anisotropic etching solution and (ii) render the electrode potential of the masked, metal coated single crystal silicon wafer, in said anisotropic etching solution, more anodic than that of a masked single crystal silicone wafer alone.
Claim 22
Dependent Claim
18 words
A method according to claim 18, wherein said metals are selected from gold, silver, platinum, palladium, and nickel.
Claim 23
Dependent Claim
19 words
A method according to claim 18, wherein said non-metal mask material is selected from silicon dioxide and silicon nitride.
Claim 24
Dependent Claim
34 words
A method according to claim 18, wherein said metal is applied to said second face of said single crystal silicon wafer by methods selected from vacuum evaporation techniques, vacuum sputtering techniques, and electrodeposition techniques.
Claim 25
Dependent Claim
49 words
A method according to claim 18, which further comprises applying an interlayer between said second face of said single crystal silicon wafer and said metal coating, said interlayer being an electrically conductive material providing adhesion between said second face of said single crystal silicon wafer and said metal coating.
Claim 26
Dependent Claim
18 words
A method according to claim 22, wherein said material comprising said interlayer is selected from chromium and titanium.
Claim 27
Dependent Claim
40 words
A method according to claim 22, wherein said interlayer material and said metal coating are applied to said second face of said single crystal silicon wafer by methods independently selected from vacuum evaporation techniques, vacuum sputtering techniques, and electrodeposition techniques.
Claim 28
Independent Claim
176 words
A method for etching a first face of a single crystal silicon wafer in an anisotropic etching solution, said method comprising: exposing a masked, metal coated single crystal silicon wafer to said anisotropic etching solution for a time necessary to etch, to a desired depth, a region of said first face of said masked, metal coated single crystal silicon wafer, said silicon wafer comprising: said first face carrying a mask material on a portion thereon in a predetermined pattern which exposes a region of said first face to be etched; and a second face, opposite said first face, carrying a metal coating which (a) is in electrical contact with and (b) coats substantially the entire surface of said second face of said single crystal silicon wafer, said coating being selected from metals which (i) are substantially resistant to attack by said anisotropic etching solution and (ii) render the electrode potential of the masked, metal coated single crystal silicon wafer, in said anisotropic etching solution, more anodic than that of a masked, single crystal silicon wafer alone.
Claim 29
Independent Claim
176 words
A method for etching a first face of a single crystal silicon wafer in an anisotropic etching solution, said method comprising: exposing a masked, metal coated single crystal silicon wafer to said anisotropic etching solution for a time necessary to etch, to a desired depth, a region of said first face of said masked, metal coated single crystal silicon wafer, said silicon wafer comprising: said first face carrying a mask material on a portion thereon in a predetermined pattern which exposes a region of said first face to be etched; and a second face, opposite said first face, carrying a metal coating which (a) is in electrical contact with and (b) coats substantially the entire surface of said second face of said single crystal silicon wafer, said coating being selected from metals which (i) are substantially resistant to attack by said anisotropic etching solution and (ii) render the electrode potential of the masked, metal coated single crystal silicon wafer, in said anisotropic etching solution, more anodic than that of a masked, single crystal silicon wafer alone.
Claim 30
Dependent Claim
55 words
A method according to claim 25, which further comprises applying an external anodic voltage to said masked, metal coated single crystal silicon wafer, said voltage being less than that which causes the electrode potential of said masked, metal coated single crystal silicon wafer to exceed the passivation potential of a masked, single crystal silicon wafer.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
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| 3.5 Years (Year 4) | 1991-08-23 | 1992-02-22 | 1992-08-23 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1995-08-23 | 1996-02-22 | 1996-08-23 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1999-08-23 | 2000-02-22 | 2000-08-23 | $7700.00 | Window Closed / Lapsed |