Process for polishing glass substrate
AssigneeAsahi Glass Company, Limited
InventorsKoji Otsuka, Masabumi Ito
Life of this patent
Estimating the term…
Abstract
A process for polishing a glass substrate required to have high-degree of flatness and smoothness, is provided. A preliminarily polished glass substrate is applied with a surface treatment by a first-step gas-cluster ion beam etching to improve the flatness, and then, the glass substrate is applied with a surface treatment by a second-step gas-cluster ion beam etching having different irradiation conditions of those of the first-step gas-cluster ion beam etching to improve the surface roughness, whereby the glass substrate is finish-polished to have a flatness of at most 0.05 μm and a surface roughness (Rms) of at most 0.25 nm.
Claims5
A polishing process, comprising:
- applying a surface treatment to a preliminarily polished TiO2-containing quartz glass substrate having a flatness of at most 0.5 μm and a surface roughness of at most 0.001 μm by a first gas cluster ion-beam etching to improve the flatness of the glass substrate to be at most 0.05 μm, and subsequently applying a surface treatment to the glass substrate by a second gas cluster ion-beam etching under irradiation conditions different from those of the first gas cluster ion-beam etching to improve the surface roughness of the glass substrate, such that the glass substrate is finish-polished to have a flatness of at most 0.05 μm and a surface roughness (Rms) of at most 0.25 nm,
- wherein a source gas for the first gas cluster ion-beam etching is selected from a group consisting of SF6;
- Ar ;
- O2;
- NF3;
- a mixed gas containing SF6, Ar and O2;
- and a mixed gas containing NF3, Ar and O2, and wherein a source gas for the second gas cluster ion-beam etching is selected from a group consisting of O2;
- CO2;
- and a mixed gas of O2 and CO2, and
- wherein the acceleration voltage of the cluster ions in the first gas cluster ion-beam etching is set to be higher than an acceleration voltage of the cluster ions in the second gas cluster ion-beam etching.
Dependencies are inferred from the claim text.