Production of high purity amorphous silica and polysilicon by a low temperature silicofluoride process
碩士 === 國立聯合大學 === 材料科學工程學系碩士班 === 94 === The research is to develop a chemical process for purification of natural quartz sand and transfer such technology to those factories that still using conventional floating and washing technique in Taiwan. Conventional floating and washing methods may produce...
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| Format: | Others |
| Language: | zh-TW |
| Published: |
2006
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| Online Access: | http://ndltd.ncl.edu.tw/handle/02465999981653010781 |
| Summary: | 碩士 === 國立聯合大學 === 材料科學工程學系碩士班 === 94 === The research is to develop a chemical process for purification of natural quartz sand and transfer such technology to those factories that still using conventional floating and washing technique in Taiwan. Conventional floating and washing methods may produce quartz sand with 95~99 wt.% purity that is not satisfied by both semiconductor and planar display industries. Quartz crucible for growth of silicon wafer requires purity of silica at 99.995 wt.% level. Glass sheets for liquid crystal display and plasma display also require high purity silica as raw materials. The purpose is to establish capabilities of manufacturing high purity silica raw materials.
The experimental results show that high purity SiO2 (99.995%) can be obtained by the re-crystallization of (NH4)2SiF6 at temperatures as low as 140℃.The UMG polysilicon can be produced by heating the purified (NH4)2SiF6 above 500℃ in H2/Ar atmosphere. FTIR and XRD results show that amorphous polysilicon granules can be prepared after heat-treatment of (NH4)2SiF6 in a reducing atmosphere. The reduction of silicofluoride salts is a viable method for the production of UMG-Si.
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