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Polycrystalline silicon rod

a technology of polycrystalline silicon and polycrystalline crystalline materials, applied in the direction of crystal growth process, polycrystalline material growth, silicon compounds, etc., can solve the problems of dislocation, production yield decline, unmelted polycrystalline, etc., and achieve the effect of remarkably suppressing the occurrence of dislocation

Inactive Publication Date: 2019-12-05
SHIN ETSU CHEM IND CO LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Benefits of technology

The present invention provides a polycrystalline silicon rod that can significantly reduce dislocations and is ideal for producing single-crystalline silicon using the FZ method.

Problems solved by technology

It has been known that, if unmelted polycrystalline silicon remains and floats in the silicon melt when the single-crystalline silicon is grown by the CZ method, the unmelted polycrystalline silicon causes the occurrence of dislocation.
Japanese Patent Laid-Open No. 2008-285403 reports that, when single crystal growth is performed according to the FZ method using the polycrystalline silicon rod in which the needle crystal has been deposited as a raw material, the inhomogeneous microstructure of the polycrystalline silicon rod causes each of crystallites to be non-uniformly melted, and the unmelted crystallite reaches a solid-liquid interface of single-crystalline silicon being grown through a melting zone, thereby causing dislocation.
Once the dislocation occurs, the single-crystalline silicon ingot cannot be obtained any longer, and as a result the production yield decreases.
However, according to investigations by the present inventors, it has become clear that the measures disclosed in the prior art literature make it difficult to make sure to suppress the occurrence of the dislocation when the single-crystalline silicon is grown in the FZ method or the CZ method.

Method used

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  • Polycrystalline silicon rod
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Experimental program
Comparison scheme
Effect test

experiment 1

[0035]First, five kinds of polycrystalline silicon rods (rods A to E) were prepared under different deposition conditions according to the Siemens method using trichlorosilane as a raw material, and a crystal piece (evaluation sample) having a principal surface set in a radial direction perpendicular to the axis direction of a silicon core was collected from each of the polycrystalline silicon rods.

[0036]Each of the samples was analyzed (magnification ratio: 5,000 times) by an EBSD method to obtain a crystal grain size distribution from the obtained image. FIGS. 2 and 3 show photographs when polycrystalline silicon rods as the rods A and E are observed with an optical microscope. A crystal grain size distribution (a crystal grain size distribution at an area ratio) for each of the samples and a “yield” when the polycrystalline silicon rod was used as the raw material for production of single-crystalline silicon according to the FZ method were summarized in Table 1.

[0037]When a lengt...

experiment 2

[0039]In addition to the rods A and B, three kinds of polycrystalline silicon rods (rods F to H) were prepared under different deposition conditions by the Siemens method using trichlorosilane as a raw material. A crystal piece (evaluation sample) having a principal surface set in the axis direction of a silicon core as a direction different from that of “experiment 1” was collected from each of the five kinds of polycrystalline silicon rods.

[0040]Each of the samples was analyzed (magnification ratio: 5,000 times) by an EBSD method, and a crystal grain size distribution was obtained from the obtained image. A crystal grain size distribution (a crystal grain size distribution at an area ratio) for each of the samples and a “yield” when the polycrystalline silicon rod was used as the raw material for production of single-crystalline silicon by the FZ method were summarized in Table 2. The meaning of the “yield” is as described above.

TABLE 2Crystal grain size distribution (%),Surface r...

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Abstract

Provided is a polycrystalline silicon rod suitable as a raw material for production of single-crystalline silicon. A crystal piece (evaluation sample) is collected from a polycrystalline silicon rod grown by a Siemens method, and a polycrystalline silicon rod in which an area ratio of a crystal grain having a particle size of 100 nm or less is 3% or more is sorted out as the raw material for production of single-crystalline silicon. When single-crystalline silicon is grown by an FZ method using the polycrystalline silicon rod as a raw material, the occurrence of dislocation is remarkably suppressed.

Description

BACKGROUND OF THE INVENTIONField of the Invention[0001]The present invention relates to a polycrystalline silicon rod grown by a Siemens method, and particularly relates to a polycrystalline silicon rod suitable as a raw material for production of single-crystalline silicon according to a floating zone method (FZ method).Description of the Related Art[0002]Polycrystalline silicon is used as a raw material for semiconductor single-crystalline silicon or solar cell silicon. As a method for producing polycrystalline silicon, the Siemens method has been widely known. The Siemens method generally includes contacting a silane source gas with a heated silicon core to deposit polycrystalline silicon on the surface of the silicon core using a chemical vapor deposition (CVD) method.[0003]When a polycrystalline silicon rod is produced by the Siemens method, two vertical silicon cores and one horizontal silicon core are assembled in a square arch shape (inverted U shape). The end parts of the s...

Claims

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Application Information

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IPC IPC(8): C01B33/035
CPCC01P2004/16C01B33/035C01P2002/70C01B33/03C30B13/00C30B15/00C30B28/14C30B29/06
Inventor HOSHINO, NARUHIRONETSU, SHIGEYOSHIOKADA, TETSUROISHIDA, MASAHIKO
Owner SHIN ETSU CHEM IND CO LTD