| 摘要 |
PURPOSE:Low-melting glass reducing occurrence of memory error, obtained by making a content of radioactive isotopes of unavoidable impurities <= a specific amount. CONSTITUTION:Lead borate glass consisting of about 70-85wt% PbO and about 10-13wt% B2O3 as main component, which are blended with a small amount of Al2O3, SiO2, ZnO, PbF2, etc., is used low-melting glass for sealing semicoductor devices airtightly. A content of radioactive isotopes of unavoidable impurities contains in the glass is limited to <20ppb, and number of counts of radioactive alpha particle is <=0.1CPH/cm<2>. By using this glass, semiconductor devices having high reliability free from occurrence of memory error are obtained.
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