Patent US4789646A successfully refreshed from Google Patents.
US4789646A
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Method for selective surface treatment of semiconductor structures
Assignee: Philips North America LLC
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Filing: 1987-07-20
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Granted: 1988-12-06
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Expires: 2007-07-20
Abstract
Abstract Surface features of a semiconductor structure above a predetermined level are exposed for selective treatment (e.g., etching) by forming a layer of a solvent-expanded polymer on the surface of the structure, and allowing the layer to dry and cure, thereby relaxing to the predetermined level, at which it protects the underlying structure during treatment. Subsequently, the protective layer is removed by rinsing in a solvent.
Inventors
- 👤 Mark A. Davis
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-07 11:45
CPC Classifications
H; H10; H10P; H10P50/00; H10P50/69; H10P50/691; H10P50/692; H10P14/00; H10P14/60; H10P14/68; H10P14/683; H10P50/20; H10P50/28; H10P50/282; H10P50/283; H10P50/60; H10P50/64; H10P50/642
Claims Analysis
Total Claims: 22
Claim 1
Independent Claim
153 words
A method for the selective treatment of surface features of a semiconductor structure on a planar substrate, the features lying above a predetermined vertical level in the structure, the method comprising: (a) covering the surface of the structure, including the features to be treated, with a continuous layer of a solvent-expanded, relaxable, room temperature curing polymer composition, to a level above the predetermined level by an amount sufficient to result in the upper surface of the layer dropping to the predetermined level upon drying and curing of the layer; (b) allowing the solvent-expanded layer to dry and cure, thereby relaxing and decreasing in volume, causing the upper surface of the layer to drop to the predetermined level, and causing the layer to withdraw from surface features lying above the predetermined level, thus exposing the surface features for treatment; (c) treating the exposed surface features; and (d) removing the polymer layer from the structure.
Claim 2
Independent Claim
153 words
A method for the selective treatment of surface features of a semiconductor structure on a planar substrate, the features lying above a predetermined vertical level in the structure, the method comprising: (a) covering the surface of the structure, including the features to be treated, with a continuous layer of a solvent-expanded, relaxable, room temperature curing polymer composition, to a level above the predetermined level by an amount sufficient to result in the upper surface of the layer dropping to the predetermined level upon drying and curing of the layer; (b) allowing the solvent-expanded layer to dry and cure, thereby relaxing and decreasing in volume, causing the upper surface of the layer to drop to the predetermined level, and causing the layer to withdraw from surface features lying above the predetermined level, thus exposing the surface features for treatment; (c) treating the exposed surface features; and (d) removing the polymer layer from the structure.
Claim 3
Dependent Claim
52 words
The method of claim 1 in which the polymer composition is characterized by small chained polymer components which are loosely crosslinked, which can be swollen by the addition of a non-polar solvent or an increase in pH and which will relax upon loss of the solvent to form a cured protective layer.
Claim 4
Dependent Claim
23 words
The method of claim 2 in which the polymer compositon has an average molecular weight of about 72 to 4500 grams per mole.
Claim 5
Dependent Claim
23 words
The method of claim 3 in which the polymer composition has an average molecular weight of from 120 to 1200 grams per mole.
Claim 6
Dependent Claim
33 words
The method of claim 1 in which the polymer composition is selected from the group consisting of water-soluble acrylic resin compositions and alcohol-soluble acrylic resin compositions having both hydroxyl and carboxyl functional groups.
Claim 7
Dependent Claim
27 words
The method of claim 5 in which the solvent-expanded polymer composition has a volume of about 1 to 10 times the initial volume of the polymer composition.
Claim 8
Dependent Claim
20 words
The method of claim 6 in which the solvent is a mixture of water and at least one non-polar solvent.
Claim 9
Dependent Claim
26 words
The method of claim 7 in which the non-polar solvent is present in the amount of at least 3 percent by volume of the total solvent.
Claim 10
Dependent Claim
37 words
The method of claim 1 in which the thickness of the solvent-expanded layer covering the projections to be treated is up to about sixty percent of the thickness of the layer surrounding the projections to be treated.
Claim 11
Dependent Claim
38 words
The method of the claim 9 in which the thickness of the solvent-expanded layer covering the projections to be treated is up to about 25 percent of the thickness of the layer surrounding the projections to be treated.
Claim 12
Dependent Claim
28 words
The method of claim 1 in which the solvent-expanded layer decreases in volume in the amount of from about 5 to 40 volume percent during drying and curing.
Claim 13
Dependent Claim
24 words
The method of claim 1 in which the predetermined level is at least 400 angstroms above the tops of surface features to be protected.
Claim 14
Dependent Claim
11 words
The method of claim 1 in which the substrate is silicon.
Claim 15
Dependent Claim
16 words
The method of claim 13 in which the surface features to be treated are silicon dioxide.
Claim 16
Dependent Claim
18 words
The method of claim 14 in which the surface features to be treated are removed by chemical etching.
Claim 17
Dependent Claim
28 words
The method of claim 15 in which the chemical etchant is selected from the group consisting of hydrofluoric acid, aqueous hydrofluoric acid solution and buffered hydrofluoric acid solution.
Claim 18
Dependent Claim
15 words
The method of claim 13 in which the surface features to be treated are silicon.
Claim 19
Dependent Claim
17 words
The method of claim 17 in which the surface features to be treated are doped with impurities.
Claim 20
Dependent Claim
27 words
The method of claim 18 in which the impurities are both n-type and p-type and are doped at different levels to form one or more pn junctions.
Claim 21
Dependent Claim
23 words
The method of claim 1 in which etching is followed by depositing at least one layer of a material on the etched surface.
Claim 22
Dependent Claim
21 words
The method of claim 20 in which the material is selected from the group consisting of silicon and refractory metal tungstates.
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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) | 1991-12-06 | 1992-06-06 | 1992-12-06 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1995-12-06 | 1996-06-06 | 1996-12-06 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1999-12-06 | 2000-06-06 | 2000-12-06 | $7700.00 | Window Closed / Lapsed |