Method for recovering abrasive particles
AssigneesKurita Water Industries Ltd., NEC Corporation
InventorsYoshihiro Hayashi, Kouichi Yabe, Tetsuo Mizuniwa
Life of this patent
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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.
Claims6
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.
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.
Dependencies are inferred from the claim text.