Recovery of coolant and abrasive grains used in slicing semiconductor wafers
AssigneesShin-Etsu Handotai Co., Ltd., Mimasu Semiconductor Industry Co., Ltd., Ohtomo Chemical Ind., Corp., Hitachi Zosen Metal Works Co., Ltd.
InventorsKohei Toyama, Etsuo Kiuchi, Kazuo Hayakawa, Shingo Kaburagi, Akio Ashida, Takara Ito, Kuniaki Noami
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Abstract
A system for reusing water soluble slurry waste fluid wherein separated available abrasive grains and extracted water soluble coolant are reused. This system is capable of reducing a disposal cost due to a reduction of a load to a waste water disposal plant by effectively reusing water soluble slurry waste fluid, and making a contribution to a reduction of a total slicing cost by reusing abrasive grains and water soluble coolant.
Claims14
A process for reusing water soluble slurry waste fluid used when semiconductor ingots are sliced with a wire saw slicing apparatus, which comprises the steps of:
- (a) decreasing viscosity of water soluble slurry waste fluid
- (b) separating the water soluble slurry waste fluid of low viscosity into separated abrasive grains and waste liquid consisting of a suspended solid part and a liquid part;
- (c) extracting water soluble coolant from the waste liquid consisting of the suspended solid part and the liquid part with a coagulation separating operation including the sub-steps of:
- (c1) adding bentonite as a coagulating agent to the waste liquid consisting of the suspended solid part and the liquid part;
- (c2) concentrating the liquid part from the waste liquid added with the coagulating agent to form coagulation flocks;
- (c3) extracting the water soluble coolant by solid-liquid separation of the waste liquid consisting of the suspended solid adsorbed to the coagulation flocks and the concentrated liquid part,
- thereafter discarding the suspended solid part as useless sludge;
- and
- (d) reusing the separated grains and the extracted water soluble coolant.
Dependencies are inferred from the claim text.