Silicon semiconductor wafer and method for producing the same

A silicon semiconductor substrate obtained from a silicon single crystal grown by the Czochralski method, characterized by the fact that the density of crystal defects is so distributed as to decrease from the center of thickness of the substrate to the surface thereof, the surface density of crystal defects measuring not less than 0.1 μm as reduced to diameter on the surface of the substrate is not more than one piece/cm2, the volumetric density of crystal defects measuring not less than 0.1 μm as reduced to diameter at a depth of 0.1 μm is not more than 1% of that at the center of thickness of the substrate, and the nitrogen content at the center of thickness of the substrate is not less than 1×1013 atoms/cm3 and not more than 1×1016 atoms/cm3.

A method for the production of a silicon semiconductor substrate, characterized by growing a silicon single crystal by the Czochralski method from a molten silicon containing not less than 1×1016 atoms/cm3 and not more than 1.5×1019 atoms/cm3 of nitrogen, obtaining a silicon semiconductor substrate from said silicon single crystal, and heat-treating said silicon semiconductor substrate at a temperature of not less than 1000° C. and not more than 1300° C. for not less than one hour.

A silicon semiconductor substrate, characterized by being produced by a procedure which comprises preparing as a substrate wafer a silicon wafer having a nitrogen content of not less than 1.0×1013 atoms/cm3 and not more than 1.0×1016 atoms/cm3 and depositing on the surface of the substrate wafer a silicon single crystal layer by the epitaxial method.

A silicon semiconductor substrate obtained by preparing as a substrate wafer a silicon wafer having an oxygen content of not less than 1.0×1017 atoms/cm3 and depositing on the surface of the substrate wafer a silicon single crystal layer by the epitaxial method, characterized by the fact that the density of crystal defects measuring not less than 0.1 μm as reduced to diameter is not more than 5×104 pieces/cm3 at least in the region reaching a depth of 1 μm from the interface between the substrate wafer and the silicon single crystal layer deposited by the epitaxial method.

A silicon semiconductor substrate obtained by preparing as a substrate wafer a silicon wafer having an oxygen content of not less than 1.0×1017 atoms/cm3 and depositing on the surface of the substrate wafer a silicon single crystal layer by the epitaxial method, characterized by the fact that at least in the region reaching a depth of 1 μm from the interface between the substrate wafer and the silicon single crystal layer deposited by the epitaxial method, the density of crystal defects measuring not less than 20 nm as reduced to diameter is not more than 5×105 pieces/cm3.

A method for the production of a silicon semiconductor substrate, characterized by preparing as a substrate wafer a silicon wafer obtained from a silicon single crystal grown from a molten silicon containing not less than 1.0×1016 atoms/cm3 and not more than 1.0×1019 atoms/cm3 of nitrogen and depositing on the surface of the substrate wafer a silicon single crystal layer by the epitaxial method.

A method for the production of a silicon semiconductor substrate, characterized by preparing as a substrate wafer a silicon wafer obtained from a silicon single crystal grown by the Czochralski method at a cooling speed of not less than 2.0° C./minute through the range of crystal temperature from the solidification point to 800° C. and depositing on the surface of the substrate wafer a silicon single crystal layer by the epitaxial method.

A method for the production of a silicon semiconductor substrate, characterized by preparing as a substrate wafer a silicon wafer obtained from a silicon single crystal grown by the Czochralski method at a cooling speed of not less than 1.0° C./minute through the range of crystal temperature from 800° C. to 400° C. and depositing on the surface of the substrate wafer a silicon single crystal layer by the epitaxial method.

A method for the production of a silicon semiconductor substrate, characterized by preparing as a substrate wafer a silicon wafer grown by the Czochralski method and, during the growth by pulling, cooled through the range of crystalline temperature from the solidification point to 800° C. at a cooling speed of not less than 2.0° C./minute and subsequently through the range of crystal temperature of 800° C.-400° C. at a cooling speed of not less than 1.0° C./minute and depositing on the surface of the substrate wafer a silicon single crystal layer by the epitaxial method.