Komatsu Electronic Metals Co., Ltd.

Sumco Techxiv Corporation

Komatsu Denshi Sinzoku Kabushiki

Kouichirou Hayashida

Susumu Maeda

Shiro Yoshino

Hisami Motoura

Takahisa Sugiman

Masayoshi Danbata

Kouzo Nakamura

Katsuhiko Sugisawa

An epitaxial wafer and a high-temperature heat treatment wafer having an excellent gettering capability are obtained by performing epitaxial growth or a high-temperature heat treatment. A relational equation relating the density to the radius of an oxygen precipitate introduced in a silicon crystal doped with nitrogen at the time of crystal growth can be derived from the nitrogen concentration and the cooling rate around 1100&#xb0; C. during crystal growth, and the oxygen precipitate density to be obtained after a heat treatment can be predicted from the derived relational equation relating the oxygen precipitate density to the radius, the oxygen concentration, and the wafer heat treatment process. Also, an epitaxially grown wafer and a high-temperature annealed wafer whose oxygen precipitate density has been controlled to an appropriate density are obtained, using conditions predicted by the method.

Nitrogen doped silicon wafer and manufacturing method thereof

A method for producing a silicon ingot through pulling up a silicon single crystal according to the Czochralski method, wherein the silicon single crystal is pulled up while being doped with nitrogen in such a condition as to form a part having a nitrogen content of 5&times;10 atoms/cm to 1&times;10 atoms/cm . A silicon wafer having a nitrogen content of 5&times;10 atoms/cm to 1&times;10 atoms/cm which is suitable for being treated with heat in a non-oxidizing atmosphere is manufactured of an ingot produced by using the method. The method can be used for producing a silicon wafer being doped with nitrogen and having satisfactory characteristics for use in a semiconductor device.

Silicon wafer and method for manufacture thereof, and method for evaluation of silicon wafer

The method of evaluating silicon wafers according to this invention is capable of predicating degradation of the quality of oxide film insulation, which is incurred, on the silicon wafers, by process faults or local residual strains undetectable by the naked eye. The method includes the following steps of: removing selectively a surface of a silicon wafer treated by mirror polishing by using an etching selectivity caused by an unordinary surface state; counting the number of etch pits on the surface of the silicon wafer with the aid of an optical microscope; and judging the quality of the silicon wafer based on the etch pit density, which is calculated from the above number of etch pits, and the threshold value of etch pit density. The threshold value of etch pit density of the silicon wafer treated by selective etching is set to be below 5.times.10.sup.5 pits/cm.sup.2, and improvements to the processing of production lines relating to low-quality silicon wafers can be made.

Method of evaluating silicon wafers

Growing community of inventors

Kanagawa, Japan

Kouichirou Hayashida