Vitreous silica crucible and evaluation method of the same
US10024784B2 · kind B2 · utility
Assignee
Inventors
Key dates
| Filing date | Oct 13, 2017 |
| Grant date | Jul 17, 2018 |
| Priority date | — |
| Expiry date | Oct 13, 2037 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG01N2201/0683
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
A vitreous silica crucible used to pull up silicon single crystal includes: a cylindrical straight body portion, a corner portion formed at a lower end of the straight body portion, and a bottom portion connected with the straight body portion via the corner portion, wherein the vitreous silica crucible further comprises: an opaque outer layer enclosing bubbles therein; and a transparent inner layer from which bubbles are removed, wherein the residual distortion's distribution obtained by measuring the silica glass's inner surface in a non-destructed state has an optical path difference which is 130 nm or less, which residual distortion's distribution is measured using a distortion-measuring apparatus which converts a linearly polarized light into circularly polarized light and then irradiates the crucible's wall.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.