Patent US4549374A successfully refreshed from Google Patents.
US4549374A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Method for polishing semiconductor wafers with montmorillonite slurry
Assignee: International Business Machines Corp
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Filing: 1985-01-14
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Granted: 1985-10-29
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Expires: 2005-01-14
Abstract
Abstract Semiconductor wafers are polished with an abrasive slurry which is prepared by dispersing montmorillonite clay in deionized water. The pH of the slurry is adjusted to 9.5 to 12.5 by adding alkali such as NaOH and KOH.
Inventors
- 👤 Jagtar S. Basi
- 👤 Eric Mandel
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-30 04:17
CPC Classifications
H; H10; H10P; H10P90/00; H10P90/12; H10P90/129; C; C09; C09G; C09G1/00; C09G1/02; H10P50/00
Claims Analysis
Total Claims: 9
Claim 1
Independent Claim
64 words
A method for polising the surface of a semiconductor wafer to render said surface smooth and flat, said method comprising: polishing the wafer surface with a surfactant-free slurry consisting primarily of powdered montmorillonite mineral colloidally suspended in deionized water and an alkaline solution in an amount suffficient to adjust the pH value of said suspension to be in the range of 9.5 to 12.5.
Claim 2
Independent Claim
64 words
A method for polising the surface of a semiconductor wafer to render said surface smooth and flat, said method comprising: polishing the wafer surface with a surfactant-free slurry consisting primarily of powdered montmorillonite mineral colloidally suspended in deionized water and an alkaline solution in an amount suffficient to adjust the pH value of said suspension to be in the range of 9.5 to 12.5.
Claim 3
Dependent Claim
20 words
The method of claim 1 wherein the weight percent of montmorillonite powder is about 2 to 10 of said suspension.
Claim 4
Dependent Claim
65 words
A colloidal liquid composition free of surfactants and oxidizing agents and specifically suitable for relatively inexpensive polishing of semiconductor substrates said composition consisting of a mixture of about 2 to 10 percent by weight of montmorillonite clay deionized water, and an alkali compound of sodium hydroxide in an amount sufficient to render the pH value of said mixture in the range of 9.5 to 12.5.
Claim 5
Dependent Claim
65 words
A colloidal liquid composition free of surfactants and oxidizing agents and specifically suitable for relatively inexpensive polishing of semiconductor substrates said composition consisting of a mixture of about 2 to 10 percent by weight of montmorillonite clay deionized water, and an alkali compound of sodium hydroxide in an amount sufficient to render the pH value of said mixture in the range of 9.5 to 12.5.
Claim 6
Dependent Claim
14 words
The composition as recited in claim 3 wherein said alkaline compound is potassium hydroxide.
Claim 7
Independent Claim
139 words
A method of polishing a silicon semiconductor wafer surface comprising: (a) applying to said silicon wafer surface by means of a polishing pad a polishing slurry consisting of 2-10 percent by weight of colloidal montmorillonite mineral admixed with deionized water and the alkaline compound of NaOH, said alkaline compound being in an amount sufficient to adjust the pH value of the slurry to be in the range of 9.5-12.5, to cause a chemical reaction of said NaOH with said silicon surface and form thereon the alkaline metal silicate of Na 4 SiO 4 ; and (b) mechanically removing said Na 4 SiO 4 from said surface with said montmorillonite by rubbing said surface with said pad, whereby said silicon wafer surface is rendered free of undesirable crystal defects and surface imperfections while causing minimal degradation of said polishing pad.
Claim 8
Independent Claim
139 words
A method of polishing a silicon semiconductor wafer surface comprising: (a) applying to said silicon wafer surface by means of a polishing pad a polishing slurry consisting of 2-10 percent by weight of colloidal montmorillonite mineral admixed with deionized water and the alkaline compound of NaOH, said alkaline compound being in an amount sufficient to adjust the pH value of the slurry to be in the range of 9.5-12.5, to cause a chemical reaction of said NaOH with said silicon surface and form thereon the alkaline metal silicate of Na 4 SiO 4 ; and (b) mechanically removing said Na 4 SiO 4 from said surface with said montmorillonite by rubbing said surface with said pad, whereby said silicon wafer surface is rendered free of undesirable crystal defects and surface imperfections while causing minimal degradation of said polishing pad.
Claim 9
Dependent Claim
22 words
The method as recited in claim 5 wherein said alkaline compound is KOH and said silicate is K 4 SiO 4 .
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) | 1988-10-28 | 1989-04-29 | 1989-10-29 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1992-10-28 | 1993-04-29 | 1993-10-29 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1996-10-28 | 1997-04-29 | 1997-10-29 | $7700.00 | Window Closed / Lapsed |