Apparatus for fabricating a single-crystal semiconductor
US5853480A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Feb 18, 1997 |
| Grant date | Dec 29, 1998 |
| Priority date | — |
| Expiry date | Feb 18, 2017 |
Classification
- Technology area (CPC Y)Emerging Cross-Sectional Technologies
- CPC primaryY10T117/1088
- WIPO fieldSurface technology, coating
- WIPO sectorChemistry
Abstract
An apparatus and a method for fabricating a single-crystal semiconductor by means of a CZ method are provided for improving the quality through modification of the thermal cycle of a pulled single-crystal semiconductor. The apparatus includes a ring-shaped after heater which is capable of elevation. The method decreases the temperature gradient to smaller than 20.degree. C./cm, and preferably under 15.degree. C./cm, when the pulled single-crystal semiconductor is cooled from 1200.degree. C. to 1000.degree. C. The after heater therefore heats the single-crystal semiconductor where there is a temperature of 100.degree.-300.degree. C. lower than the range of 1200.degree.-1000.degree. C. A thermal baffle (or shield) is provided to retain a temperature gradient of larger than 20.degree. C./cm when the single-crystal semiconductor is within the temperature range between the melting point and 1250.degree. C. The after heater and the baffle (or shield) can be raised to an upper portion when polysilicon blocks are charged and a twisting step is carried out.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.