Method for manufacturing semiconductor silicon wafer composed of silicon wafer substrate and silicon monocrystalline epitaxial layer

A method for manufacturing a semiconductor silicon wafer with a silicon monocrystalline epitaxial layer, wherein a silicon monocrystalline epitaxial film with reduced SF is formed on the front surface side of a substrate sliced from a silicon single crystal ingot that is grown using the Czochralski method, the method comprising:

• a step of manufacturing substrates, being doped with phosphorus, having resistivity being adjusted to be 1.05 mΩ·cm or less, a concentration of solid-solution oxygen of 0.9×1018 atoms/cm3 or less, and sliced such that the slicing angle against the primary plane orientation falls in a range of 0.1 degrees to 0.4 degree;
• a step of forming a silicon oxide film with a thickness of at least 300 nm or thicker only on a backside of the silicon wafer substrate containing Si—P (silicon phosphorus) defects by the CVD method at a temperature of 500° C. or lower;
• a step of heat treatment, after the step of forming a silicon oxide film, in which the substrate, only on the backside of which a silicon oxide film is formed, is kept in an oxidizing atmosphere at a constant temperature of more than 1100° C. or higher and 1250° C. or lower for 30 minutes or longer and 120 minutes or shorter such that for the substrate after the heat treatment in the oxidizing atmosphere, a thickness of a surface thermal oxide film formed on the surface of the substrate is 20 nm or more to 150 nm or less, and a concentration of phosphorus (P) to a depth of 300 nm from the substrate surface is 7×1019 atoms/cm3 or less;
• a step of removal of a front surface oxide film, after the step of heat treatment, in which a thermal oxide film formed on the front surface of the substrate is removed, wherein the thickness of the CVD oxide film on the backside of the substrate remains at 300 nm or more after the step of removal of the surface thermal oxide film;
• and
• a step of deposition of a silicon monocrystalline epitaxial layer on the front surface of the substrate from which the oxide film is removed, after the step of removing the surface oxide film.