Single Crystal Silicon Plate-Shaped Body and Production Method Therefor
AssigneeTokuyama Corporation
InventorsIsao Masada, Shoji Tachibana
Life of this patent
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Abstract
A single crystal silicon plate-shaped body as cut out from an upper portion of a straight body portion of a CZ method single crystal silicon ingot has an interstitial oxygen concentration in a crystal is 25 ppma to 45 ppma and a substitutional carbon concentration is 0.5 ppma or less in a radial center. In the radial center, oxygen precipitates are not observed in a bulk in an image of 200,000 times by a transmission electron microscope, and after heating the single crystal silicon plate-shaped body at 950° C. for 60 minutes, oxygen precipitates are observed in an image of the 200,000 times, and a shape of the oxygen precipitates is observed in a polyhedral structure in an image of 2,000,000 times.
Claims9
A single crystal silicon plate-shaped body, wherein
- an interstitial oxygen concentration in a crystal is 25 ppma to 45 ppma and a substitutional carbon concentration is 0.5 ppma or less in a radial center, and
- in the radial center, oxygen precipitates are not observed in a bulk in an image of 200,000 times by a transmission electron microscope, and after heating the single crystal silicon plate-shaped body at 950° C. for 60 minutes, oxygen precipitates are observed with number density of 2×1012 pieces/cm3 or less in a bulk in an image of 200,000 times, and when the oxygen precipitates are observed in an image of 2,000,000 times, oxygen precipitates of which a shape is observed in a polyhedral structure are 75% or more.
(canceled)
A method of producing a CZ method single crystal silicon ingot, wherein
- when a single crystal silicon ingot is pulled up by a CZ method from a melt in which polycrystal silicon is melted, cooling is carried out in a cooling time of 20 hours or more and 30 hours or less from 1000° C. to 800° C. of a region where an interstitial oxygen concentration is 25 ppma to 45 ppma and a substitutional carbon concentration is 0.5 ppma or less in a radial center in a long axis direction of the ingot, and cooling from less than 800° C. to 600° C. is performed at a speed of 5° C./min to 15° C./min.
Dependencies are inferred from the claim text.