Diameter and melt measurement method used in automatically controlled crystal growth
US5961716A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Dec 15, 1997 |
| Grant date | Oct 5, 1999 |
| Priority date | — |
| Expiry date | Dec 15, 2017 |
Classification
- Technology area (CPC Y)Emerging Cross-Sectional Technologies
- CPC primaryY10T117/1008
- WIPO fieldSurface technology, coating
- WIPO sectorChemistry
Abstract
A CCD camera is used to measure the diameter of a growing crystal through optical recognition of the luminous ring at a crystal-melt interface. The result is an optical diameter control method and apparatus that eliminates the negative effects of orbit, melt-level and incorrect camera angle. The CCD camera is positioned such that it focuses on a full half of the circumference of the crystal as it is being grown. An automatic control system uses two points diametrically opposed on the crystal to measure the diameter, and a third point on the crystal closest to the camera to compute the melt level error. The automatic control system controls a crucible height and a crystal pull rate to optimize crystal diameter.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.