US5376222A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Polishing method for polycrystalline silicon
Assignee: Fujitsu Ltd
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Filing: 1992-08-31
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Granted: 1994-12-27
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Expires: 2012-08-31
Abstract
Abstract This invention discloses a polishing method for flattening an inter-level insulating film or polycrystalline silicon inside a device isolation ditch in a semiconductor fabrication process. To this end, the present invention grinds and flattens an insulating film having a step on the surface thereof by using a polishing solution containing an alkali solution and a grain, wherein a cation concentration in the alkali solution is higher than an OH - ion concentration in the alkali solution.
Inventors
- 👤 Motoshu Miyajima
- 👤 Yasuyuki Ichihashi
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-02 19:29
CPC Classifications
H; H10; H10P; H10P52/00; H10P52/40; H10P52/403; H10W; H10W10/00; H10W10/01; H10W10/041; H10W10/40
Claims Analysis
Total Claims: 4
Claim 1
Independent Claim
105 words
A method of polishing silicon comprising the steps of: a) forming a groove on a substrate; b) depositing silicon on said substrate inclusive of said groove; and c) polishing silicon at portions other than the inside of said groove using a polishing solution comprising an alkali solution having an organic compound and a grain dissolved therein, and a cation of an alkali solution having dissolved therein a neutral inorganic salt of an alkali metal or an inorganic acid, a cation concentration of said polishing solution being higher than an OH - concentration of said polishing solution, a pH of said polishing solution being below 12.5.
Claim 2
Independent Claim
105 words
A method of polishing silicon comprising the steps of: a) forming a groove on a substrate; b) depositing silicon on said substrate inclusive of said groove; and c) polishing silicon at portions other than the inside of said groove using a polishing solution comprising an alkali solution having an organic compound and a grain dissolved therein, and a cation of an alkali solution having dissolved therein a neutral inorganic salt of an alkali metal or an inorganic acid, a cation concentration of said polishing solution being higher than an OH - concentration of said polishing solution, a pH of said polishing solution being below 12.5.
Claim 3
Dependent Claim
40 words
A polishing method of polishing silicon according to claim 1, wherein said grain in said polishing solution comprises colloidal silica or silica, and said cation of said alkali solution comprises a potassium ion, a sodium ion or an ammonium ion.
Claim 4
Dependent Claim
21 words
A method of polishing silicon according to claim 6, wherein said organic compound in said polishing solution is ethylenediamine or hydrazine.
References Cited (Backward Citations)
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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) | 1997-12-26 | 1998-06-27 | 1998-12-27 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2001-12-26 | 2002-06-27 | 2002-12-27 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2005-12-26 | 2006-06-27 | 2006-12-27 | $7700.00 | Window Closed / Lapsed |