| 摘要 |
PURPOSE:To prevent the gettering of a heavy metal by a method wherein an epitaxial growing method is performed on the silicon single crystal substrate in which high density impurities are added, then a buffer layer is formed by performing a heat treatment, and an epitaxial growing method is performed again. CONSTITUTION:The oxygen on the surface of a silicon substrate 1 is outwardly diffused by performing a heat treatment on the substrate 1 at 1150 deg.C for one hour in hydrogen, and an oxygen concentration reduced layer 2 is formed. Then, the first boron-added epitaxial layer 3 of 25 mum in thickness and the resistivity of 0.1 OMEGAcm is formed by vapor growth thereon using dichlorosilane at 1100 deg.C. Subsequently, the boron in the silicon substrate 1 and oxygen concentration reduced layer 2 is diffused into the first epitaxial layer 3 by performing a heat treatment in hydrogen at 1150 deg.C for about 30 minutes, and a buffer layer 4 is formed. Then, the second epitaxial layer 5 is formed by vapor growth on the buffer layer 4 by adding boron so as to obtain the thickness of 2.5 mum and the resistivity of 1 OMEGAcm using dichlorosilane, and the wafer forming operation is finished.
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