Method for evaluating metal contamination of silicon single crystal
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United States of America Patent
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Jul 2, 2013
Grant Date -
Oct 15, 2009
app pub date -
Apr 7, 2009
filing date -
Apr 10, 2008
priority date (Note) -
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Abstract
When a silicon single crystal is grown by the CZ method using a pulling apparatus in which a voltage can be applied between a crystal suspending member and a crucible, the voltage is applied under the condition that the crystal suspending member is set as a negative electrode while the crucible is set as a positive electrode in a process for growing a lower end portion of a cylindrical portion or a tail portion which is of a non-convertible portion of the silicon single crystal. A sample wafer is collected from the lower end portion of the cylindrical portion or the tail portion, which is grown in association with the voltage application, and the metal contamination of the sample wafer is evaluated. The sample wafer has enough metal impurity concentration to evaluate the metal contamination. The metal contamination is evaluated for each of the sequentially grown silicon single crystals, so that a metal impurity generation behavior in a pulling apparatus, which is a factor in silicon single crystal metal contamination, can assuredly be grasped.
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