Fused silica glass crucible
US5730800A · kind A · utility
Assignees
Inventors
Key dates
| Filing date | Dec 17, 1996 |
| Grant date | Mar 24, 1998 |
| Priority date | — |
| Expiry date | Dec 17, 2016 |
Classification
- Technology area (CPC C)Chemistry; Metallurgy
- CPC primaryC03C2201/32
- WIPO fieldSurface technology, coating
- WIPO sectorChemistry
Abstract
An improved method is proposed for the preparation of a semiconductor silicon single crystal of N-type by the Czochralski process, which is free from the problem of occurrence of delayed OSFs as defects in the single crystal even after prolonged storage at room temperature based on the discovery that presence of a certain amount of aluminum in the melt of silicon contained in a fused silica glass crucible acts to suppress occurrence of delayed OSFs as a type of defects in the single crystal while copper as an impurity acts adversely in this regard. With a known fact that an about 30 .mu.m thick inner surface layer of the crucible is melted down into the silicon melt during the single crystal pulling-up process, namely, the invention proposes use of a crucible of which the inner surface layer of 30 .mu.m thickness contains aluminum in an average concentration of 40 to 500 ppm by weight while the content of copper is as low as possible not to exceed 0.5 ppb by weight. Alternatively, when the fused silica glass crucible is deficient in the content of aluminum, an amount of aluminum is introduced as a dopant into the melt of silicon in the crucible to supplement the content of aluminum…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.