| 摘要 |
PURPOSE:To eliminate causes of corrosion of aluminum wiring and alpha-ray software error by using a silica which does not contain uranium and thorium but contains an alkali metal oxide and impurities within the specified rate in total. CONSTITUTION:A silica used does not substantially contain uranium and thorium but contains alkali metal oxide of 10PPM or less and impurities in total contents of 100PPM. Such a high purity silica powder can be obtained by the following process. Namely, a high purity crystal silica or soluble silica is heated up to 2,000-2,500 deg.C under existence of carbon and is vaporized. The vaporized silica is collected and thereby higher purity silica can be obtained. The silica powder has a grain size of 0.1mum or less. Thereby any corrosion of aluminum wiring cannot be found even under the high temperature and high humidity ambient because it contains a very little amount of alkali and moreover even in case it is used for VLSI, and alpha-ray soft ware error is not detected because UO2 and ThO2 are not substantially contained. |
