US5647989A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Method for recovering abrasive particles
Assignee: Kurita Water Industries Ltd
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Filing: 1995-10-12
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Granted: 1997-07-15
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Expires: 2015-10-12
Abstract
Abstract A method for recovering abrasive particles of, in particular, colloidal silica, in a simple manner from a spent abrasive suspension, which requires subjecting the spent abrasive slurry (5) containing colloidal silica used for polishing a semiconductor substrate in a microfilter (1) to thereby concentrate coarse particulate impurities for being removed out of the system, subjecting the slurry (6) which has permeated through the microfilter to an ultrafiltration in an ultrafilter (2) to concentrate the retained abrasive particles and recovering this concentrate in order to recover the colloidal silica.
Inventors
- 👤 Yoshihiro Hayashi
- 👤 Kouichi Yabe
- 👤 Tetsuo Mizuniwa
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-09 13:22
CPC Classifications
B; B24; B24B; B24B57/00; B24B57/02; B24B37/00; B24B37/04; B01; B01D; B01D61/00; B01D61/14; B01D61/149; B24B55/00; B24B55/02; B24B55/03; C; C02; C02F; C02F1/00; C02F1/44; C02F1/444
Claims Analysis
Total Claims: 8
Claim 1
Independent Claim
157 words
A method for recovering abrasive particles within a desire size range from a spent abrasive suspension obtained from polishing a semiconductor substrate or a surface layer formed on said substrate, said suspension additionally contain coarse impurity particles which are coarser than said desired size range and fine impurity particles which are finer than said desired size range, said method comprising the steps of: subjecting the spent abrasive suspension to microfiltration using a microfiltration membrane which permits the permeation of a filtrate containing the abrasive particles and the fine impurity particles therethrough and retains the coarse impurity particles on the retentate side thereof; subjecting the filtrate from the microfiltration to ultrafiltration using an ultrafiltration membrane which allows water and the fine impurity particles to permeate therethrough and retains the abrasive particles on concentrate side thereof; recovering the abrasive particles from the concentrate side of said ultrafiltration membrane; and recycling said recovered abrasive particles for polishing said semiconductor substrate.
Claim 2
Independent Claim
157 words
A method for recovering abrasive particles within a desire size range from a spent abrasive suspension obtained from polishing a semiconductor substrate or a surface layer formed on said substrate, said suspension additionally contain coarse impurity particles which are coarser than said desired size range and fine impurity particles which are finer than said desired size range, said method comprising the steps of: subjecting the spent abrasive suspension to microfiltration using a microfiltration membrane which permits the permeation of a filtrate containing the abrasive particles and the fine impurity particles therethrough and retains the coarse impurity particles on the retentate side thereof; subjecting the filtrate from the microfiltration to ultrafiltration using an ultrafiltration membrane which allows water and the fine impurity particles to permeate therethrough and retains the abrasive particles on concentrate side thereof; recovering the abrasive particles from the concentrate side of said ultrafiltration membrane; and recycling said recovered abrasive particles for polishing said semiconductor substrate.
Claim 3
Dependent Claim
23 words
A method according to claim 1, wherein the abrasive particles recovered from the ultrafiltration are reused with addition of an electrolyte salt thereto.
Claim 4
Dependent Claim
22 words
A method according to claim 1, wherein the particle size range of the abrasive particles is from 2 nm to 500 nm.
Claim 5
Dependent Claim
13 words
A method according to claim 1, wherein the abrasive particles are colloidal silica.
Claim 6
Dependent Claim
16 words
The method of claim 1, wherein said coarse particles have a particle size exceeding 500 nm.
Claim 7
Independent Claim
159 words
A method for recovering abrasive particles within a desire size range from a spent abrasive suspension obtained from polishing a semiconductor substrate or a surface layer formed on said substrate, said suspension additionally contain coarse impurity particles which are coarser than said desired size range and fine impurity particles which are finer than said desired size range, said method consisting essentially of the steps of: subjecting the spent abrasive suspension to microfiltration using a microfiltration membrane which permits the permeation of a filtrate containing the abrasive particles and the fine impurity particles therethrough and retains the coarse impurity particles on the retentate side thereof; subjecting the filtrate from the microfiltration to ultrafiltration using an ultrafiltration membrane which allows water and the fine impurity particles to permeate therethrough and retains the abrasive particles on concentrate side thereof; recovering the abrasive particles from the concentrate side of said ultrafiltration membrane; and recycling said recovered abrasive particles for polishing said semiconductor substrate.
Claim 8
Independent Claim
159 words
A method for recovering abrasive particles within a desire size range from a spent abrasive suspension obtained from polishing a semiconductor substrate or a surface layer formed on said substrate, said suspension additionally contain coarse impurity particles which are coarser than said desired size range and fine impurity particles which are finer than said desired size range, said method consisting essentially of the steps of: subjecting the spent abrasive suspension to microfiltration using a microfiltration membrane which permits the permeation of a filtrate containing the abrasive particles and the fine impurity particles therethrough and retains the coarse impurity particles on the retentate side thereof; subjecting the filtrate from the microfiltration to ultrafiltration using an ultrafiltration membrane which allows water and the fine impurity particles to permeate therethrough and retains the abrasive particles on concentrate side thereof; recovering the abrasive particles from the concentrate side of said ultrafiltration membrane; and recycling said recovered abrasive particles for polishing said semiconductor substrate.
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JPH01135580A
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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) | 2000-07-14 | 2001-01-13 | 2001-07-15 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2004-07-14 | 2005-01-13 | 2005-07-15 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2008-07-14 | 2009-01-13 | 2009-07-15 | $7700.00 | Window Closed / Lapsed |