Methods for working and sensing synthetic quartz glass substrate

Patent metadata

Field	Value
Publication number	US-9599746-B2
Application number	US-201514645908-A
Country	US
Kind code	B2
Filing date	Mar 12, 2015
Priority date	Mar 17, 2014
Publication date	Mar 21, 2017
Grant date	Mar 21, 2017

Abstract

A synthetic quartz glass substrate having front and back surfaces is worked by lapping, etching, mirror polishing, and cleaning steps for thereby polishing the front surface of the substrate to a mirror-like surface. The etching step is carried out using a hydrofluoric acid solution at pH 4-7.

First claim

The invention claimed is:

1. A method for working a synthetic quartz glass substrate, comprising the steps, in the recited order, of lapping, etching, mirror polishing, and cleaning the synthetic quartz glass substrate having front and back surfaces for thereby polishing the front surface to a mirror-like surface,
wherein, in the etching step, etching of the front and back surfaces of the synthetic quartz glass substrate is performed with hydrofluoric acid or buffered hydrofluoric acid at pH 4 to 7, and
wherein a heat treatment in a heating furnace is carried out between the etching step and the mirror polishing step.

2. The method of claim 1 wherein the back surface of the synthetic quartz glass substrate at the end of lapping step has a surface roughness (Ra) of 0.1 to 0.2 μm.

3. The method of claim 1 wherein the back surface of the synthetic quartz glass substrate at the end of etching step has a surface roughness (Ra) of 0.15 to 0.25 μm.

4. The method of claim 1 wherein the back surface of the synthetic quartz glass substrate at the end of mirror polishing step has a surface roughness (Ra) of 0.15 to 0.25 μm.

5. The method of claim 1 wherein the front surface of the synthetic quartz glass substrate at the end of mirror polishing step has a surface roughness (Ra) of 0.1 to 0.8 nm, which is less than the surface roughness (Ra) of the back surface.

6. The method of claim 1 wherein the cleaning step includes cleaning with 0.1 to 2% by weight hydrofluoric acid and/or pure water while applying ultrasonic wave in an intermediate or high frequency band to the front and back surfaces of the substrate.

7. The method of claim 1 , further comprising, after the cleaning step, the step of forming a thin film on the back surface of the synthetic quartz glass substrate by vapor deposition.

8. The method of claim 1 , wherein a temperature of the heat treatment is in a range of 600 to 1,200° C. and a heating rate is in a range of 100 to 300° C./hr.

Assignees

• Shinetsu Chemical Co

Inventors

• Ueda Shuhei
• Takeuchi Masaki

Classifications

• H10P74/203

  Structural properties, e.g. testing or measuring thicknesses, line widths, warpage, bond strengths or physical defects · CPC title

• C03C2217/252

  Al · CPC title

• G01V8/12 Primary

  using one transmitter and one receiver · CPC title

• C03C23/007

  by thermal treatment · CPC title

• C23C16/402

  Silicon dioxide · CPC title