# US 10,865,498 B2 · Polycrystalline silicon rod, method for producing polycrystalline silicon rod, and single-crystalline silicon

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- Number: US 10,865,498 B2
- Document ID: US10865498B2
- Status: Granted
- Kind: B2
- Application number: 16/157,858
- Filed: 2018-10-11
- Published: 2019-03-14
- Granted: 2020-12-15
- Earliest claimed: 2014-05-07
- Assignees: Shin-Etsu Chemical Co., Ltd.
- Applicants: Shin-Etsu Chemical Co., Ltd.
- Inventors: Shuichi Miyao; Shigeyoshi Netsu; Tetsuro Okada
- Web page: https://patentgrep.com/patent/US10865498B2

## CPC

- C30B 13/08: adding crystallising materials or reactants forming it in situ to the molten zone
- C01B 33/035: by decomposition or reduction of gaseous or vaporised silicon compounds in the presence of heated filaments of silicon, carbon or a refractory metal, e.g. tantalum or tungsten, or in the presence of heated silicon rods on which the formed silicon is deposited, a silicon rod being obtained, e.g. Siemens process
- C30B 15/02: adding crystallising materials or reactants forming it in situ to the melt
- C30B 29/06: Silicon
- C30B: SINGLE-CRYSTAL GROWTH (by using ultra-high pressure, e.g. for the formation of diamonds, B01J3/06); UNIDIRECTIONAL SOLIDIFICATION OF EUTECTIC MATERIAL OR UNIDIRECTIONAL DEMIXING OF EUTECTOID MATERIAL; REFINING BY ZONE-MELTING OF MATERIAL (zone-refining of metals or alloys C22B); PRODUCTION OF A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE (casting of metals, casting of other substances by the same processes or devices B22D; working of plastics B29; modifying the physical structure of metals or alloys C21D, C22F); SINGLE CRYSTALS OR HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; AFTER-TREATMENT OF SINGLE CRYSTALS OR A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE (for producing semiconductor devices or parts thereof H10); APPARATUS THEREFOR
- C01B: NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; {METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C}

## 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-sin2Ψ diagram can be obtained.

## Claims

### Claim 1

A method of producing a polycrystalline silicon rod, comprising:
(i) growing a polycrystalline silicon rod by a Siemens process, and
(ii) after said growing, heat-treating the polycrystalline silicon rod, which was grown, at a temperature ranging from 750° C. to 900° C. for stress relief,
wherein said heat-treating is conducted inside a furnace in which the polycrystalline silicon rod was grown and
wherein said heat-treating occurs in absence of growing the polycrystalline silicon rod.