Conical portion growth control method and apparatus
US5223078A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Oct 15, 1991 |
| Grant date | Jun 29, 1993 |
| Priority date | — |
| Expiry date | Oct 15, 2011 |
Classification
- Technology area (CPC Y)Emerging Cross-Sectional Technologies
- CPC primaryY10T117/1008
- WIPO fieldSurface technology, coating
- WIPO sectorChemistry
Abstract
A conical portion growth control method and an apparatus used in the method grow a conical portion 32B of a single crystal rod 32 by pulling the crystal rod from a melt 16 heated by a heater 14 in the Czochralski method, and aim to enhance reproducibility of the shape of the conical portion 32B and shorten the conical portion 32B. The control method has the steps of presetting a target value pattern 66 of the temperature of a concave portion 46 formed on a heat-insulating material 18 and a target value pattern 64 of the diameter change rate of a growing portion of the crystal rod, measuring the diameter of the crystal growing portion, calculating the change rate of the diameter, measuring the temperature of the concave portion, correcting the target temperature based on a difference between the calculated value and the target value of the diameter change rate, and controlling the amount of electricity supplied to the heater so that the measured temperature becomes equal to the corrected target temperature.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.