Control system for the czochralski process
US4857278A · kind A · utility
17Cited by
7References
12Claims
0Family size
Assignee
Inventors
Key dates
| Filing date | Jul 13, 1987 |
| Grant date | Aug 15, 1989 |
| Priority date | — |
| Expiry date | Jul 13, 2007 |
Classification
- Technology area (CPC Y)Emerging Cross-Sectional Technologies
- CPC primaryY10T117/1008
- WIPO fieldSurface technology, coating
- WIPO sectorChemistry
Abstract
The control system includes a master loop for controlling crystal interface diameter and slave control loops for controlling the melt and the crystal thermal environment. Diameter and meniscus angle signals are partitioned into both a low frequency and a high frequency signal. The low frequency signal is used to adjust the set point of the melt. The higher frequency signal is used to control the crystal pull rate. The crystal control slave loop regulates crystal heat flux which may include following a heat flux trajectory. The heat flux trajectory may also be used to adjust the melt temperature set point.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.