Preferential etching method and silicon single crystal...

Etching a substrate: processes – Nongaseous phase etching of substrate – Etching inorganic substrate

Reexamination Certificate

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C216S083000, C216S103000, C438S745000, C438S753000

Reexamination Certificate

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07811464

ABSTRACT:
There is provided a preferential etching method wherein a preferential etchant which contains at least a hydrofluoric acid whose composition by volume falls within the range of 0.02 to 0.1, a nitric acid whose composition by volume falls within the range of 0.5 to 0.6, an acetic acid whose composition by volume falls within the range of 0.2 to 0.25, and water is used to etch a silicon single crystal substrate whose electrical resistivity is less than 10 mΩ·cm at a rate higher than 0.1 μm/min, thereby eliciting BMDs on a surface of the silicon single crystal substrate. As a result, the preferential etching method that can evaluate and utilize characteristics of crystal defects, especially BMDs in an ultralow-resistance silicon single crystal substrate whose electrical resistivity is less than 10 mΩ·cm, which cannot be readily detected by conventional techniques, by performing preferential etching using a chromeless etchant containing no harmful chrome can be provided.

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Oct. 20, 2009 Office Action issued in Japanese Patent Application No. 2005-020094 (with partial translation).
Japanese Industrial Standard H 0609:1999; “Test methods of crystalline defects in silicon by preferential etch techniques,” Feb. 29, 2000.

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