| 摘要 |
Manufacture of a crucible from fused quartz comprises: (a) fabricating a green compact from porous, amorphous, fused quartz permeated with a substance promoting crystallisation of the crucible; (b) drying the obtained compact, (c) filling the compact with metal or metalloid; and (d) heating for 1-1000 hours at 900-2000 deg C Preferred Features: Between stages (b) and (c) the green compact is subjected to thermal treatment during which grain narrowing occurs while maintaining the open porosity of the green compact. The material promoting crystallisation, especially cristobalite formation, is selected from compounds of barium, aluminum and boron, most preferably Ba(OH)2, barium oxide or barium carbonate, and less preferably aluminum oxide. The compound can be applied in the form of a liquid by spraying, dip coating, or impregnation, or in the form of a solid by adding it to a dispersion containing SiO2 and using the dispersion to make the green compact. The compound is used in amount 0.01-1000 micro g/g of SiO2. The metal or metalloid is selected from polycrystalline silicon and single crystal silicon, preferably of high purity, and their mixtures. After fusion of the metal or metalloid a single crystal is drawn from the crucible. Independent claims are given for: (a) a process for pulling a single crystal of metal or metalloid, preferably silicon; and (b) utilization of a non-sintered, porous, amorphous fused quartz green compact, non-sintered or pre-sintered, which is infiltrated by a substance that promotes cristobalite, for pulling a single crystal. |
