| 摘要 |
PURPOSE: To prevent impurities from entering a substrate in an intrinsic gettering process by carrying out intrinsic/gettering process comprised of a first heat treatment process to a third heat treatment process of various specific conditions with a silicon nitride film provided to a silicon board surface. CONSTITUTION: An about 1500Å-thick nitride film 2 is deposited by a CVD method after a heat oxide film for preventing a surface of a substrate 1 from being roughened is formed and a first heat treatment is carried out for one hour at about 900 to 1350 deg.C. Then, oxygen contained in a surface of the substrate 1 passes through a nitride film 2 and is diffused, and a denuded layer 3 is formed in a surface of the substrate 1 and an intrinsic point defect generation region 4 is formed in an inside thereof. Thereafter, when second (400 to 650 deg.C) and third (900 to 1350 deg.C for 0 to 5 hours) heat treatments are carried out, oxygen precipitation nucleus is formed in an intrinsic point defect generation region 4 and an oxygen precipitation is formed. Metallic impurities are prevented from entering following a heat treatment process by providing a nitride film 2 to a surface of the substrate 1.
|
