The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Sep. 06, 2011
Filed:
May. 25, 2007
Hiroshi Hayakawa, Tokyo, JP;
Tokuji Maeda, Tokyo, JP;
Hiroshi Hayakawa, Tokyo, JP;
Tokuji Maeda, Tokyo, JP;
Sumco Corporation, Tokyo, JP;
Abstract
The liquid surface position of the melt in the crucible in the silicon single crystal growth process utilizing the Czochralski method is monitored using the melt surface position on the occasion of seeding as a reference position and an estimated melt surface position can be calculated according to every situation, so that the distance between the melt and the thermal shield or water-cooling structure can be controlled with high precision. When the estimated melt surface position passes a preset upper limit and approaches the thermal shield, an alarm goes off and, further, when the melt comes into contact with the thermal shield or approaches the water-cooling structure, an alarm goes off if desired and, at the same time, the crucible is forcedly stopped from moving, so that a serious accident such as steam-incurred explosion resulting from the melt coming into contact with the water-cooling structure can be prevented. Accordingly, the apparatus can be widely applied as a melt surface position monitoring apparatus making it possible to safely operate any silicon single crystal growth apparatus utilizing the Czochralski method.