Process for the preparation of polycrystalline silicon

Patent metadata

Field	Value
Publication number	US-10400329-B2
Application number	US-201414785918-A
Country	US
Kind code	B2
Filing date	Mar 24, 2014
Priority date	Apr 22, 2013
Publication date	Sep 3, 2019
Grant date	Sep 3, 2019

Abstract

Siemens reactors for polysilicon deposition may employ faster and/or more economical deposition conditions without reduction in yield, by pre-sorting polysilicon rods into different quality classifications prior to comminution, and further sorting the polysilicon fragments in each classification into further classifications.

First claim

The invention claimed is:

1. A process for producing comminuted polycrystalline silicon, comprising depositing polycrystalline silicon on support bodies present in at least one reactor to obtain polycrystalline silicon rods, deinstalling the polycrystalline silicon rods from the at least one reactor, and comminuting the deinstalled polycrystalline silicon rods into chunks, wherein the deinstallation of the polycrystalline silicon rods from the at least one reactor is followed by, and the comminution of the deinstalled polycrystalline silicon rods into chunks is preceded by, classification of whole polycrystalline silicon rods or rod form parts separated therefrom into at least two quality classes of polycrystalline silicon on the basis of at least one classification feature, said at least two quality classes being sent to separate further processing steps.

2. The process of claim 1 , wherein the at least one classification feature of the polycrystalline silicon rods or rod form parts is the position of the silicon in the rod or rod form part being classified.

3. The process of claim 1 , wherein the at least one classification feature of the polycrystalline silicon rods or rod form parts is the position in the reactor of the rod or rod form part being classified.

4. The process of claim 1 , wherein the at least one classification feature of the polycrystalline silicon rods or rod form parts is a visually discernible feature on the rod or rod form part being classified.

5. The process of claim 1 , wherein the at least one classification feature of the polycrystalline silicon rods or rod form parts is a measurable feature of the rod or rod form part being classified.

6. The process of claim 5 , wherein the at least one classification feature of the polycrystalline silicon rods or rod form parts is the rod diameter of the rod or rod form part being classified.

7. The process of claim 1 , wherein the at least one classification feature of the polycrystalline silicon rods or rod form parts is contamination of the surface or of the volume of the rod or rod form part being classified.

8. The process of claim 1 , wherein the polycrystalline silicon rods classified into at least two quality classes include whole polycrystalline silicon rods.

9. The process of claim 1 , wherein rod form parts from a whole polycrystalline silicon rod of the deinstalled polysilicon rods are assigned to at least two quality classes.

10. The process of claim 1 , wherein the comminution of the polycrystalline silicon rods or rod form parts into chunks is followed by a classification of the chunks into at least two quality classes on the basis of at least one feature selected from the group consisting of porosity, cracks, holes, stains, rod diameter and rod shape.

11. The process of claim 1 , wherein following said separate further processing steps, at least two product classes including at least two of three classes a) through c):
a) polycrystalline silicon for monocrystalline solar applications,
b) polycrystalline silicon for multicrystalline solar application, and
c) polycrystalline silicon for semiconductor applications, are collected.

12. The process of claim 1 , wherein the support bodies are filament rods consisting essentially of silicon.

13. The process of claim 11 , wherein one product class collected is polycrystalline silicon for semiconductor applications, and this class is comprised of dense cores of the polycrystalline silicon rods.

14. The process of claim 1 , wherein at least one quality class is a dense first polycrystalline silicon quality class, and a further second quality class is of polycrystalline silicon with a density less than the density of the polycrystalline silicon of the first quality class.

15. The process of claim 1 , wherein the classification into quality classes is based on one or more features selected from the group consisting of porosity, cracks, holes, stains and rod shape.

16. A process for producing polycrystalline silicon, comprising depositing polycrystalline silicon on support bodies present in at least one reactor to obtain polycrystalline silicon rods, deinstalling the polycrystalline silicon rods from the at least one reactor, comminuting the deinstalled polycrystalline silicon rods into chunks, wherein the deinstallation of the polycrystalline silicon rods from the at least one reactor is followed by, and the comminution of the deinstalled polycrystalline silicon rods into chunks is preceded by, classification of the polycrystalline silicon rods or rod form parts derived therefrom into at least two quality classes on the basis of the rod or rod part diameter and at least one additional feature, said at least two quality classes being sent to separate comminution steps, wherein the at least one additional feature is the position of silicon in the rod, the position of the rod in the reactor, a visually discernible feature, a measurable feature, or a combination thereof.

17. A process for producing polycrystalline silicon, comprising depositing polycrystalline silicon on support bodies present in at least one reactor to obtain polycrystalline silicon rods, deinstalling the polycrystalline silicon rods from the at least one reactor, comminuting the deinstalled polycrystalline silicon rods into chunks, wherein the deinstallation of the polycrystalline silicon rods from the at least one reactor is followed by, and the comminution of the deinstalled polycrystalline silicon rods into chunks is preceded by, classification of whole polycrystalline silicon rods, or rod form parts separated from one polycrystalline silicon rod, into at least two quality classes on the basis of the rod diameter and at least one additional feature, said at least two quality classes being sent to separate comminution steps, wherein the at least one additional feature is a feature selected from the group consisting of;
position of the silicon in the rod,
position of the rod in the reactor
fracture characteristics of the rods or rod parts spontaneously or on fragmentation by
mechanical, thermal, or electrical methods, refractive indices of the rods or rod parts for sound, infrasound, or ultrasound waves
emission spectrum of the rods or rod parts after excitation including thermal, electrical, or optically excitations, or in an unexcited state
electromagnetic absorption spectrum of the rods or rod parts
neutron activatability of the rods or rod parts
shape of the rods or rod parts
length of the rods
weight of the rods or rod parts
porosity of the rods or rod parts
density of the rods or rod parts
contamination of the surface or of the volume selected from the group consisting of
surface contamination of the rods or rod parts with metals, nonmetals or compositions thereof,
contamination of the volume of the rods or rod parts with metals, nonmetals or compositions thereof,
contamination of the surface of the rods or rod parts with dust
air temperature, air composition and time up to classification
state of the integrity and contamination of deposition reactor after deposition
the interface of the filament rods with the deposited silicon including color, shape, thickness and composition of any existing intermediate layer, and bond strength
contact of the rods or rod parts with extraneous materials
the odor of the rods or rod parts
sound of the rods or rod parts after mechanical excitation
intrinsic vibration frequency of the rods or rod parts
electrical resistance of the rods or rod parts
refractive indices of the rods or rod parts for electromagnetic waves
X-ray diffract

Assignees

• Wacker Chemie Ag

Inventors

• Kerscher Michael
• Pech Reiner
• Sandner Armin

Classifications

• G01N29/09

  by measuring mechanical or acoustic impedance · CPC title

• B02C23/08

  Separating or sorting of material, associated with crushing or disintegrating (B02C23/18 takes precedence {; beater mills combined with sifting devices B02C13/13, B02C13/14; for tumbling mills B02C17/1835}) · CPC title

• C23C16/24

  Deposition of silicon only · CPC title

• G01N2291/0234

  Metals, e.g. steel · CPC title

• C23C16/56

  After-treatment · CPC title