US4889586A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Method for polishing AlGaAs surfaces
Assignee: Mitsubishi Chemical Corp
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Filing: 1989-03-30
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Granted: 1989-12-26
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Expires: 2009-03-30
Abstract
Abstract The present invention polishes the surface of a substrate or epitaxial layer of Al x Ga 1-x As wherein 0<x<1.0 with a polishing liquid comprising an aqueous alkali hypochlorite solution or a mixture of said aqueous solution with an alkali carbonate, said liquid being regulated to a pH value ranging from 8.0 to 11.0, and further containing a powder such as SiO 2 or a colloidal material such as colloidal silica having a fine particle size to afford a planar mirror-surface to said surface, thereby preventing wafer cracking or pattern flowing during patterning by photomasks and improving yields.
Inventors
- 👤 Masahiro Noguchi
- 👤 Osamu Yamamoto
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-24 04:21
CPC Classifications
H; H10; H10P; H10P90/00; H10P90/12; H10P90/129
Claims Analysis
Total Claims: 8
Claim 1
Independent Claim
35 words
A method for polishing AlGaAs surfaces, in which a substrate or epitaxial layer of Al x Ga 1-x As wherein 0<x<1.0 is polished on the surface with the use of a hypochlorite base polishing liquid.
Claim 2
Independent Claim
35 words
A method for polishing AlGaAs surfaces, in which a substrate or epitaxial layer of Al x Ga 1-x As wherein 0<x<1.0 is polished on the surface with the use of a hypochlorite base polishing liquid.
Claim 3
Dependent Claim
65 words
A method for polishing AlGaAs surfaces as claimed in claim 1, wherein said polishing liquid comprises an aqueous alkali hypochlorite solution or a mixed solution of said aqueous solution with an alkali carbonate, is regulated to a pH value of 8.0 to 11.0, and is added with a powdery or colloidal material having a fine particle size, such as powdery or colloidal SiO 2 .
Claim 4
Dependent Claim
26 words
A method for polishing AlGaAs surfaces as claimed in claim 2, wherein said powdery or colloidal material has a particle size of 0.01 to 0.1 μm.
Claim 5
Dependent Claim
24 words
A method for polishing AlGaAs surfaces as claimed in claim 2, wherein said powdery or colloidal material has a concentration of 0.1 to 5%.
Claim 6
Dependent Claim
29 words
A method for polishing AlGaAs surfaces as claimed in claim 1 or 2, which is carried out at two or more steps with varied concentrations of said polishing liquid.
Claim 7
Dependent Claim
43 words
A method for polishing AlGaAs surfaces as claimed in claim 5, wherein a primary polishing liquid comprises 1 to 3% of sodium hypochlorite and 1 to 5 g/l of sodium carbonate, and is regulated to a pH value ranging from 9 to 11.
Claim 8
Dependent Claim
43 words
A method for polishing AlGaAs surfaces as claimed in claim 5, wherein a secondary polishing liquid comprises 0.1 to 3% of sodium hypochlorite and 1 to 2 g/l of sodium carbonate, and is regulated to a pH value ranging from 8 to 10.
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) | 1992-12-25 | 1993-06-26 | 1993-12-26 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1996-12-25 | 1997-06-26 | 1997-12-26 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2000-12-25 | 2001-06-26 | 2001-12-26 | $7700.00 | Window Closed / Lapsed |