SILICON WAFER, SILICON EPITAXIAL WAFER AND METHOD FOR MANUFACTURING THESE

摘要

PROBLEM TO BE SOLVED: To provide a method for manufacturing a silicon wafer to surely maintain high resistivity even if a device is thermally processed when manufactured. SOLUTION: The silicon wafer has a DZ layer adjacent to a surface and an oxygen deposition layer in a bulk. Lattice oxygen densities in the DZ layer, in the oxygen deposition layer and a transition region between the DZ layer and the oxygen transition layer are 8 ppma or less. The silicon epitaxial wafer has an epitaxial layer formed on the surface of the silicon wafer. In the method for manufacturing the silicon wafer, a monocrystal silicon ingot having an initial lattice oxygen density of 10-25 ppma is grown by Czochralski method. The monocrystal silicon ingot is processed to obtain wafers. The wafer is processed by the first thermal process for 2-5 hours at 950-1,050 deg.C, the second thermal process for 4-10 hours at 450-550 deg.C, the third thermal process for 2-8 hours at 750-850 deg.C and the fourth thermal process for 8-24 hours at 950-1,100 deg.C.