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US 4,910,156 AGranted
Neutron transmutation doping of a silicon wafer
AssigneeToshiba Ceramics Co., Ltd.
InventorsShin'ichiro Takasu, Michihiro Ohwa, Kazuhiko Kashima, Eiichi Toji, Kazumoto Homma
Life of this patent
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Abstract
A silicon wafer and a method of producing a silicon wafer comprising a phosphor-doping method of doping phosphor into a single silicon crystals by transmuting isotope Si.sup.30 contained in said single silicon crystals made by the CZ method or the MCZ method into p.sup.31 under neutron irradiation to said single silicon crystals.
Claims2
A method of producing a P-doped silicon wafer, comprising the steps of:
- preparing a single silicon crystal made by the MCZ method and having an oxygen content within a range from 5.times.10.sup.16 atoms/cm.sup.3 to 10.times.10.sup.17 atoms/cm.sup.3, and
- doping phosphor into said crystal by transmuting isotope Si.sup.30 contained in said crystal into P.sup.31, under a neutron irradiation to said crystal at an irradiation dose of fast neutrons less than 3.times.10.sup.16 /cm.sup.2.
A method of producing a silicon wafer having a low density of A center type defects for use in epitaxial growing, comprising the steps of:
- preparing a silicon wafer having an oxygen content of not less than 5.times.10.sup.16 atoms/cm.sup.3, and
- irradiating fast neutrons to said wafer at a dose of not less than 1.times.10.sup.12 /cm.sup.2 by a nuclear reactor having a thermal neutron/fast neutron ratio of not greater than 30.
Dependencies are inferred from the claim text.