Method for evaluating abrasive grains, and method for manufacturing silicon wafer

Patent metadata

Field	Value
Publication number	US-10416145-B2
Application number	US-201515535567-A
Country	US
Kind code	B2
Filing date	Oct 9, 2015
Priority date	Dec 26, 2014
Publication date	Sep 17, 2019
Grant date	Sep 17, 2019

Abstract

An evaluation method of abrasive grains used in an ingot-cutting slurry includes: an evaluation solution preparation step in which abrasive grains including polishing grains and impurities are dissolved in a solvent to prepare an evaluation solution; a sedimentation step in which a container containing the evaluation solution is left still to settle the polishing grains; a measurement step in which a turbidity of supernatant of the evaluation solution is measured using the measurement device; and an estimation step in which an amount of the impurities is estimated based on the measurement result of the turbidity of the supernatant.

First claim

The invention claimed is:

1. An evaluation method of abrasive grains suitable for an ingot-cutting slurry, the evaluation method comprising:
providing abrasive grains comprising polishing grains consisting of green silicon carbide, which contributes to cutting an ingot, and
impurities consisting of a form of tree carbon, which do not contribute to cutting the ingot:

preparing an evaluation solution by dissolving a test portion of the abrasive grains in a solvent;
settling the polishing grains by leaving still a container containing the evaluation solution for a period of time sufficient to settle the green silicon carbide but to leave the impurities present in a supernatant of the evaluation solution;
measuring a turbidity of the supernatant of the evaluation solution using a turbidity measurement device;
determining that the abrasive grains are unusable if the turbidity of the supernatant exceeds a preset level; and
determining that the abrasive grains is acceptable if the turbidity of the supernatant does not exceed a predetermined level.

2. The evaluation method of abrasive grains according to claim 1 , wherein
the solvent is water, pure water or ultra-pure water.

3. The evaluation method of abrasive grains according to claim 1 , wherein
the settling is performed after shaking the container containing the evaluation solution.

4. The evaluation method of abrasive grains according to claim 1 , wherein
the measuring is performed after diluting the supernatant.

5. A manufacturing method of a silicon wafer using a wire saw, the method comprising:
evaluating one or a series of batches of abrasive grains used in the ingot-cutting slurry according to claim 1 ; and
where a batch of abrasive grains is determined to be acceptable, preparing the ingot-cutting slurry using the batch of abrasive grains; and
cutting an ingot using the wire saw and the ingot-cutting slurry to produce the silicon wafer.

Assignees

• Sumco Corp

Inventors

• MINAMIHATA Yuuji

Classifications

• H10P52/00

  Grinding, lapping or polishing of wafers, substrates or parts of devices · CPC title

• G01N21/94

  Investigating contamination, e.g. dust (G01N21/85 takes precedence) · CPC title

• G01N21/85

  Investigating moving fluids or granular solids · CPC title

• B28D5/007

  Use, recovery or regeneration of abrasive mediums (for grinding and polishing in general B24B57/00) · CPC title

• G01N21/51

  inside a container, e.g. in an ampoule (G01N21/53 takes precedence) · CPC title