Method and apparatus for melt level detection in czochralski crystal growth systems
US5286461A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Sep 20, 1991 |
| Grant date | Feb 15, 1994 |
| Priority date | — |
| Expiry date | Sep 20, 2011 |
Classification
- Technology area (CPC Y)Emerging Cross-Sectional Technologies
- CPC primaryY10T117/1012
- WIPO fieldSurface technology, coating
- WIPO sectorChemistry
Abstract
The present invention is directed toward a melt level detection system for detecting the level of the melt surface in crystal growing systems that utilize a crucible containing a pool of melt from which a seed is withdrawn to grow the crystal. The detection system utilizes a light source for directing a light beam at the melt, and a light detection apparatus positioned on the other side of the melt for receiving the beam of light that is reflected off of the melt. The detection system utilizes a single element linear detector that provides output signals relating to whether the light beam is illuminating the detector, and where on the detector the illumination occurs. A computer system is utilized to implement an algorithm that processes the output signals from the detector which are continually sampled over time. The algorithm disregards the location data sent from the detector if it determines that the light beam was not incident on the detector for a given sample. By analyzing location data only for samples generated when the light beam was incident on the detector, the algorithm determines an average location of the melt level for a predetermined number of samples and assumes t…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.