# US 2019/0375642 A1 · Method for producing polycrystalline silicon

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- Number: US 2019/0375642 A1
- Document ID: US20190375642A1
- Status: Published application
- Kind: A1
- Application number: 16/477,814
- Filed: 2017-12-28
- Published: 2019-12-12
- Earliest claimed: 2017-01-16
- Assignees: Tokuyama Corporation
- Applicants: Tokuyama Corporation
- Inventors: Yuichi INOUE
- Web page: https://patentgrep.com/patent/US20190375642A1

## CPC

- C01B 33/03: by decomposition of silicon halides or halosilanes or reduction thereof with hydrogen as the only reducing agent
- C01B: NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; {METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C}

## Abstract

Provided is a method which not only prevents (i) accumulation of fine silicon powder in a separation device and a pipe which are provided in steps after passage of a filter and (ii) damage to a pump, but also reduces adhesion of a silane oligomer to the filter. A method, in accordance with an embodiment of the present invention, for producing polycrystalline silicon, includes: a silicon deposition step; a separation step; and a fine powder removal step of removing the fine silicon powder by passing a chlorosilane condensate through a filter.

## Claims

### Claim 1

A method for producing polycrystalline silicon, comprising the steps of:
a) depositing polycrystalline silicon by reacting a chlorosilane compound and hydrogen together;
b) separating, into a chlorosilane condensate and a gas component, exhaust gas which is discharged through the step a), the chlorosilane condensate containing fine silicon powder; and
c) removing the fine silicon powder by passing the chlorosilane condensate containing the fine silicon powder through a filter.

### Claim 2 (depends on 1)

The method as set forth in claim 1, wherein:
the chlorosilane condensate is carried to the filter by use of a slurry pump.

### Claim 3 (depends on 2)

The method as set forth in claim 2, further comprising the step of:
circulating, to the step b), part of the chlorosilane condensate discharged from the slurry pump.

### Claim 4 (depends on 2)

The method as set forth in claim 2, wherein:
the chlorosilane condensate is carried to the slurry pump after having passed through a strainer.

### Claim 5 (depends on 1)

The method as set forth in claim 1, wherein:
the fine silicon powder is contained in an amount of 0.01% by mass to 0.3% by mass in the chlorosilane condensate.

### Claim 6 (depends on 1)

The method as set forth in claim 1, wherein:
the filter has a pore size of 1 μm to 5 μm.

### Claim 7 (depends on 1)

The method as set forth in claim 1, wherein:
the chlorosilane condensate having been subjected to the step c) is distilled so that a chlorosilane compound is produced, and the chlorosilane compound is circulated to the step a).