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:
Dec. 15, 2020
Filed:
Oct. 11, 2018
Shin-etsu Chemical Co., Ltd., Tokyo, JP;
SHIN-ETSU CHEMICAL CO., LTD., Tokyo, JP;
Abstract
In the present invention, once a polycrystalline silicon rod is grown by the Siemens process, the polycrystalline silicon rod is heat-treated within a temperature range from 750° C. to 900° C. to relieve residual stress in the crystal. According to the experiment of the present inventors, residual stress can be relieved satisfactorily by heat treatment at the above-described low temperature, and in addition, metal contamination cannot be induced and the physical properties of the polycrystalline silicon rod cannot be changed. The above heat treatment can be conducted inside a furnace used to grow the polycrystalline silicon rod, and can also be conducted outside a furnace used to grow the polycrystalline silicon rod. According to the present invention, a polycrystalline silicon rod with residual stress (σ) of not more than +20 MPa evaluated by a 2θ-sinΨ diagram can be obtained.