Method of and apparatus for measuring oscillation of the outside diameter of a melt surface
US5170061A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Apr 29, 1991 |
| Grant date | Dec 8, 1992 |
| Priority date | — |
| Expiry date | Apr 29, 2011 |
Classification
- Technology area (CPC Y)Emerging Cross-Sectional Technologies
- CPC primaryY10T117/1004
- WIPO fieldSurface technology, coating
- WIPO sectorChemistry
Abstract
A method and an apparatus for measuring oscillation of a melt surface in growing a single crystal by Czochralski process, particularly in growing and pulling a crystal neck portion having a small diameter of 2 to 5 mm. The image of a region where the single crystal is being grown by the Czochralski process is taken by a camera 38 and the outside diameter D.sub.o of a bright ring image 70 of a brightness not lower than a predetermined reference value E is detected in accordance with video signals produced by the camera (Steps 80-83). The amount of oscillation of the outside diameter D.sub.o is measured as the amount S.sub.v of oscillation of the melt surface near the region where the single crystal is grown. The reference value E is determined by multiplying the maximum value of the video signals in one field with a predetermined constant K. The constant K is a value which, when the velocity of pulling of the single crystal is fixed to zero, substantially maximizes the amount of S.sub.v of oscillation of the outside diameter D.sub.o.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.