JP2004196643A - Silicon - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a product obtained through highly efficient reduction of silicon tetrachloride with a zinc gas for realizing cost reduction and large-amount supply of high-purity raw material silicon, i.e., the greatest problems in a photovoltaic power generation system which is the most preferable system for energy generation from the standpoint of improving global environment. <P>SOLUTION: A high-purity silicon crystal is produced by heating and evaporating zinc metal and silicon tetrachloride in an evaporator, introducing the evaporated silicon tetrachloride and zinc metal into a reactor by employing an inert gas as a carrier, and carrying out reduction in a gasifying atmosphere. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to high-purity silicon produced by a zinc gasification reduction method of silicon tetrachloride in which high-purity zinc gas and high-purity silicon tetrachloride gas are reacted.
[0002]
[Prior art]
In the conventional method, TCS (silane trichloride) is reduced with hydrogen gas to produce high-purity silicon. However, since the reaction efficiency is low and large power is consumed, about 5% of high-purity polycrystalline silicon is used. It is expensive at 2,000 yen / kg, and only some of the unqualified products are used for solar cells.
[0003]
[Problems to be solved by the invention]
The present invention is to produce high-purity silicon crystals by reacting high-purity zinc gas and high-purity silicon tetrachloride gas in a gasification atmosphere at 900 ° C to 1100 ° C.
[0004]
[Means for Solving the Problems]
In order to solve the above problems, an evaporator for heating and evaporating metal zinc and silicon tetrachloride respectively, and reacting a predetermined amount of the evaporated silicon tetrachloride and metal zinc while performing temperature control and flow rate control using an inert gas as a carrier. The high-purity silicon according to claim 1 is produced when the reaction product is introduced into a vessel to perform a reduction reaction. The rate of formation of dendritic crystals or scale-like crystals varies depending on operating conditions.
[0005]
Most of the high-purity silicon produced above consists of dendritic crystals or scale-like crystals, but the shape is not constant and includes fine particles and powder. In addition, for the convenience of handling in a post-process such as casting, the hardly-dissolved powder is removed by a sieve or the like, and then heated and melted to form a solid polycrystalline silicon.
[0006]
Embodiment 1
The quality of the product manufactured according to the above item 0004 is shown below.
(1) Measurement conditions: CZ carrot X'tal 4P measurement.
(2) Resistance: N240Ωcm (Top-5%), N160Ωcm (Top-60%)
(3) B level: P1,020 Ωcm (Top-5%), P990 Ωcm (Top-60%)
(4) LT: 130 μ-sec
[0007]
Embodiment 2
The quality of the product manufactured according to the above item 0005 is shown below.
(1) Measurement conditions: CZ carrot X'tal 4P measurement.
(2) Resistance value: N270Ωcm (Top-5%), N400Ωcm (Top-60%)
(3) B level: P240Ωcm (Top-5%), P280Ωcm (Top-60%)
(4) LT: 80 μ-sec
Embodiment 3
An example of sorting according to the size of the product manufactured according to the above item 0004 is shown below.
(1) Measurement conditions: 16 mesh screen.
(2) Percentage of those passing through the screen: 37%
(3) Proportion not passing through the screen: 63%

Claims (1)

A general solar cell which is a dendritic crystal or a scale-like crystal in which 50% by weight or more is produced by a zinc gasification reduction method of silicon tetrachloride which reacts high-purity zinc gas and high-purity silicon tetrachloride gas and does not pass through a 1 mm size screen. High-purity polycrystalline silicon with a resistance value of “N> 0.1 Ωcm” or “P> 1 Ωcm” used for battery grade.