US4801380A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Method of producing a silicon film with micropores
Assignee: Texas A&M University System
•
Filing: 1987-12-23
•
Granted: 1989-01-31
•
Expires: 2007-12-23
Abstract
Abstract The present invention relates to a method of producing micropores having diameters of less than 20 nanometers in straight sides in silicon film. The silicon film produced by this process may be attached to a substrate material and used as a filter in molecular separation processes.
Inventors
- 👤 Donald L. Parker
- 👤 Kenneth R. Hall
- 👤 James C. Holste
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-05 14:07
CPC Classifications
H; H10; H10P; H10P50/00; H10P50/60; H10P50/66; H10P50/663; H10P50/667; B; B01; B01D; B01D67/00; B01D67/0039; B01D67/0053; B01D67/006; B01D67/0065; B01D67/0072; B01D71/00; B01D71/02; B01D71/0213; C; C25; C25D; C25D11/00; C25D11/02; C25D11/32; H10P90/00; H10P90/12; H10P90/15; B01D2323/00; B01D2323/28; B01D2323/283; B01D2325/00; B01D2325/02; B01D2325/0283; Y; Y10; Y10S; Y10S264/00; Y10S264/48
Claims Analysis
Total Claims: 23
Claim 1
Independent Claim
47 words
A method comprising: providing a membrane for separating materials in a molecular regime by, (a) anodizing crystalline silicon to form a porous silicon film; and (b) securing the porous silicon film on a porous substrate having pores greater in diameter than the pores in the porous film.
Claim 2
Independent Claim
47 words
A method comprising: providing a membrane for separating materials in a molecular regime by, (a) anodizing crystalline silicon to form a porous silicon film; and (b) securing the porous silicon film on a porous substrate having pores greater in diameter than the pores in the porous film.
Claim 3
Dependent Claim
26 words
The method of claim 1 wherein the crystalline silicon is monocrystalline silicon, and the porous silicon film is formed on the surface of the monocrystalline silicon.
Claim 4
Dependent Claim
26 words
The method of claim 2, further comprising removing the porous silicon film from the monocrystalline silicon, and transferring the porous silicon film to the porous substrate.
Claim 5
Dependent Claim
26 words
The method of claim 1 wherein the crystalline silicon is polycrystalline silicon and the porous silicon film is formed by vapor deposition on the porous substrate.
Claim 6
Dependent Claim
38 words
The method of claim 4 further comprising the steps of: (a) drying the porous film in a vacuum; and (b) oxidizing the porous film at a temperature greater than room temperature to reduce the diameter of the pores.
Claim 7
Dependent Claim
11 words
The method of claim 4 wherein the substrate material is graphite.
Claim 8
Dependent Claim
12 words
The method of claim 4 wherein the substrate material is stainless steel.
Claim 9
Dependent Claim
16 words
The method of claim 1 wherein said anodizing is performed in a solution of hydrofluoric acid.
Claim 10
Dependent Claim
12 words
The method of claim 8 wherein said hydrofluoric acid solution comprises ethanol.
Claim 11
Dependent Claim
17 words
The method of claim 5 wherein oxidizing takes place at a pressure in excess of atmospheric pressure.
Claim 12
Dependent Claim
15 words
The method of claim 5 wherein said oxidizing takes place in a pure oxygen atmosphere.
Claim 13
Dependent Claim
15 words
The method of claim 1 wherein the pores produced by oxidation have relatively straight sides.
Claim 14
Dependent Claim
24 words
The method of claim 5 further comprising the step of periodically measuring the density of the polysilicon film until there are no density changes.
Claim 15
Dependent Claim
9 words
The product made by the method of claim 12.
Claim 16
Independent Claim
110 words
A method comprising the steps of: providing a membrane for separating materials in a molecular regime by, (a) placing a doped monocrystalline silicon wafer into an anodization solution to produce pores in the monocrystalline silicon; (b) increasing the anodization current while the wafer is in the anodization solution; (c) peeling a porous layer of monocrystalline silicon film off the wafer; (d) drying the monocrystalline silicon film in a vacuum; (e) attaching the porous monocrystalline silicon film to a porous substrate material using a binder; and (f) oxidizing the monocrystalline silicon film at a temperature greater than room temperature to reduce the diameter of the pores to less than 60 angstroms.
Claim 17
Independent Claim
110 words
A method comprising the steps of: providing a membrane for separating materials in a molecular regime by, (a) placing a doped monocrystalline silicon wafer into an anodization solution to produce pores in the monocrystalline silicon; (b) increasing the anodization current while the wafer is in the anodization solution; (c) peeling a porous layer of monocrystalline silicon film off the wafer; (d) drying the monocrystalline silicon film in a vacuum; (e) attaching the porous monocrystalline silicon film to a porous substrate material using a binder; and (f) oxidizing the monocrystalline silicon film at a temperature greater than room temperature to reduce the diameter of the pores to less than 60 angstroms.
Claim 18
Dependent Claim
16 words
The method of claim 15 wherein said anodizing is performed in a solution of hydrofluoric acid.
Claim 19
Dependent Claim
12 words
The method of claim 16 wherein said hydrofluoric acid solution comprises ethanol.
Claim 20
Dependent Claim
18 words
The method of claim 15 wherein said oxidizing takes place at a pressure in excess of atmospheric pressure.
Claim 21
Dependent Claim
15 words
The method of claim 15 wherein said oxidizing takes place in a pure oxygen atmosphere.
Claim 22
Dependent Claim
15 words
To method of claim 15 wherein the pores produced by oxidation have relatively straight sides.
Claim 23
Dependent Claim
9 words
The product made by the method of claim 15.
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) | 1992-01-31 | 1992-08-01 | 1993-01-31 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1996-01-31 | 1996-08-01 | 1997-01-31 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2000-01-31 | 2000-08-01 | 2001-01-31 | $7700.00 | Window Closed / Lapsed |