Method for producing single crystal
US6416576B1 · kind B1 · utility
Assignee
Inventors
Key dates
| Filing date | May 25, 2001 |
| Grant date | Jul 9, 2002 |
| Priority date | — |
| Expiry date | May 25, 2021 |
Classification
- Technology area (CPC C)Chemistry; Metallurgy
- CPC primaryC30B15/26
- WIPO fieldSurface technology, coating
- WIPO sectorChemistry
Abstract
In pulling a single crystal by CZ method, stable pulling up is carried out in a pulling rate as fast as possible while a crystal deformation is controlled to an aimed value and density of grown-in defects is suppressed to a value below an upper limit value. As an index of deformation of the single crystal from a perfect circle, the aimed value of the crystal deformation is previously determined. The upper limit value of a pulling rate necessary to suppress a defect density to an allowable range is previously calculated from distribution of grown-in defects in the crystal section, the single crystal is pulled up according to a predetermined pulling rate, and then deviation of the achieved value from the aimed value of the crystal deformation in pulling is calculated. The deviation is converted to a correction of the pulling rate. This correction is added to a set value of the pulling rate in the pulling and the result is used as a temporary set value of the pulling rate in the next pulling. The temporary set value is compared with the upper limit value of the above described pulling rate and the smaller value is determined as the pulling rate in the next runs.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.