US5157876A
Expired / Lapsed
US
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Stress-free chemo-mechanical polishing agent for II-VI compound semiconductor single crystals and method of polishing
Assignee: Boeing Co
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Filing: 1991-11-04
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Granted: 1992-10-27
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Expires: 2011-11-04
Abstract
Abstract In the present invention STRESS-FREE CHEMO-MECHANICAL POLISHING AGENT FOR II-VI COMPOUND SEMICONDUCTOR SINGLE CRYSTALS AND METHOD OF POLISHING, a II-VI compound semiconductor single crystal wafer is polished smooth to within 50 angstroms by using a mixture of water, colloidal silica and bleach including sodium hypochlorite applied under time and pressure control to achieve chemo-mechanical polishing. Many such compound crystals are not susceptible to polishing by prior art methods.
Inventors
- 👤 Daniel Medellin
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-23 18:16
CPC Classifications
B; B24; B24B; B24B37/00; B24B37/04; B24B37/07; B24B37/10; B24B37/105; B24B37/107; B24D; B24D3/00; B24D3/02; B24D3/04; B24D3/14
Claims Analysis
Total Claims: 12
Claim 1
Independent Claim
75 words
The method of polishing a compound semiconductor single crystal from Group II-VI, comprising the steps of: making a polishing agent consisting solely of a mixture of water, colloidal silica and sodium hypochlorite; establishing relative motion between a group II-VI wafer to be polished and said mixture; and, controlling the time of exposing the wafer to said mixture and the pressure between the wafer and the mixture to obtain a wafer surface smoothness within fifty angstroms.
Claim 2
Independent Claim
75 words
The method of polishing a compound semiconductor single crystal from Group II-VI, comprising the steps of: making a polishing agent consisting solely of a mixture of water, colloidal silica and sodium hypochlorite; establishing relative motion between a group II-VI wafer to be polished and said mixture; and, controlling the time of exposing the wafer to said mixture and the pressure between the wafer and the mixture to obtain a wafer surface smoothness within fifty angstroms.
Claim 3
Dependent Claim
33 words
The method of claim 1, wherein: applying said mixture to a pad on a turntable; using a wafer holder to apply said wafer against said pad; and, using controllable pressure on the holder.
Claim 4
Dependent Claim
15 words
The method of claim 2, wherein: mounting said wafer holder to rotate with the turn-table.
Claim 5
Dependent Claim
12 words
The method of claim 3 wherein: making the pad of poromeric polyurethane.
Claim 6
Dependent Claim
98 words
A substantially stress-free chemo-mechanical polishing method for group II-VI compound crystal semiconductors consisting of the following steps: mixing water, colloidal silica and sodium hypochlorite to form a polishing agent for said semiconductors; insuring that the volume of silica is many times the volume of sodium hypochlorite in said agent; establishing relative motion between a group II-VI semiconductor to be polished and said mixture; and, controlling the time of exposing said semiconductor to be polished to said mixture and the pressure between said semiconductor to be polished and the mixture to obtain a semiconductor surface smoothness within fifty angstroms.
Claim 7
Dependent Claim
98 words
A substantially stress-free chemo-mechanical polishing method for group II-VI compound crystal semiconductors consisting of the following steps: mixing water, colloidal silica and sodium hypochlorite to form a polishing agent for said semiconductors; insuring that the volume of silica is many times the volume of sodium hypochlorite in said agent; establishing relative motion between a group II-VI semiconductor to be polished and said mixture; and, controlling the time of exposing said semiconductor to be polished to said mixture and the pressure between said semiconductor to be polished and the mixture to obtain a semiconductor surface smoothness within fifty angstroms.
Claim 8
Dependent Claim
18 words
The method of claim 5, wherein: maintaining said pressure between approximately 100 and 125 grams per centimeter squared.
Claim 9
Dependent Claim
29 words
The method of claim 6, wherein: maintaining said polishing until an interferometer shows the entire polished semiconductor to exhibit light bands all across the polished portion of the semiconductor.
Claim 10
Dependent Claim
28 words
The method of claim 5 wherein: using said sodium hypochlorite to oxidize the semiconductor being polished; and, using said silica to remove the oxide resulting from said oxidation.
Claim 11
Dependent Claim
25 words
The method of claim 5, wherein: the volumetric ratio range for said agent is: water 35-50 colloidal silica 10-35 bleach 1-5 including approximately 5.25% hypochlorite.
Claim 12
Dependent Claim
32 words
The method of claim 9, wherein the semiconductor comprises mercury cadmium telluride and the preferred ratio by volume is: water 35 colloidal silica 35 bleach 5 including approximately 5.25% sodium hypochlorite and
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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) | 1995-10-27 | 1996-04-27 | 1996-10-27 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1999-10-27 | 2000-04-27 | 2000-10-27 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2003-10-27 | 2004-04-27 | 2004-10-27 | $7700.00 | Window Closed / Lapsed |