CN101186298A

CN101186298A - Method for refining and purifying crystalline silicon

Info

Publication number: CN101186298A
Application number: CNA2007100706946A
Authority: CN
Inventors: 吴振华; 汤荣发
Original assignee: Individual
Current assignee: Individual
Priority date: 2007-09-06
Filing date: 2007-09-06
Publication date: 2008-05-28
Anticipated expiration: 2027-09-06
Also published as: CN100575253C

Abstract

The invention discloses an extraction and purification method of crystalline silicon, which comprises the steps that: 1) feeding: silicon dioxide is added in a small crucible of a jacket crucible and activated carbon and catalyst are added in the crevice between the small crucible and a big crucible; 2) high temperature catalytic reaction: the jacket crucible is put into a furnace with high temperature to be catalyzed by high temperature to obtain primary crystalline silicon; 3) liquefaction reaction: the primary crystalline silicon is put into a closed glass vessel, then chlorine gas is input to liquefy the crystalline silicon to obtain liquid crystalline silicon; 4) purifying and filtering: the liquid silicon chloride is cooled and then filtered; 5) reduction and replacement: the filtered liquid is put into the closed glass vessel, and then chlorine gas is input and reduction is carried out, thus obtaining crystalline silicon with high purity; 6) cooling and drying: the crystalline silicon is cooled and dried and the finished product is obtained. The crystalline silicon extracted by the invention has high purity, can be applied to producing various solar photovoltaic energy cells and the single crystal silicon produced by the crystalline silicon extracted by the invention can be applied to producing various IC chips.

Description

Refining and purifying method of crystalline silicon

Technical Field

The invention relates to a production method of crystalline silicon, in particular to a refining and purifying method of crystalline silicon.

Background

With the acceleration of world industrialization, the demand for energy is increasing day by day. However, non-renewable energy sources such as electricity, coal, petroleum and the like are increasingly in short supply, and the environment is polluted. So the energy problem has become a bottleneck restricting the economic development. Therefore, the development and use of renewable energy are advanced to the last level, and solar energy is increasingly regarded by people due to the characteristics of inexhaustible, pollution-free, compatible and freely available for human beings. In the existing photovoltaic power generation system for converting solar energy into electric energy, crystalline silicon is mainly used as a material for converting solar energy into electric energy. The purity of crystalline silicon directly influences the conversion efficiency of the solar photovoltaic cell, the purity of crystalline silicon produced by the existing production method is usually 99.9999, and the efficiency of converting solar energy into electric energy by the crystalline silicon with the purity is only 7% -8%.

Disclosure of Invention

The invention aims to develop a method for refining and purifying high-purity crystalline silicon.

The invention aims to solve the problem that the purity of crystalline silicon produced by the existing method is low. And the low-purity crystalline silicon is used for a photovoltaic cell, and the solar energy conversion efficiency is low.

In order to solve the problem of achieving the aim, the invention adopts the following process steps: 1) feeding: adding silicon dioxide into a small crucible of a jacketed crucible, and adding activated carbon with the silicon dioxide dosage of 20-30% and catalyst nickel or nickel carbonate with the silicon dioxide dosage of 10-18% into a crack between a large crucible and the small crucible; 2) high-temperature catalytic reaction: placing the jacketed crucible in a high-temperature furnace, carrying out high-temperature catalysis, controlling the temperature to be 1600-1700 ℃, and carrying out catalytic reaction until the silicon dioxide is changed into grey black to obtain primary crystalline silicon, wherein the reaction time is controlled to be about 6 hours; 3) and (3) liquefaction reaction: placing the reacted primary crystalline silicon in a closed glass container, heating to about 75-90 ℃, vacuumizing and reducing the pressure to about negative 1 atmospheric pressure, and introducing chlorine gas to liquefy the primary crystalline silicon into liquid silicon chloride; 4) filtering and purifying: cooling the liquid silicon chloride, then filtering, and filtering to remove impurities; 5) reduction and replacement: putting the obtained filtrate into a closed glass container, introducing hydrogen at normal temperature and normal pressure, reducing, and replacing chloride ions to obtain crystalline silicon with the purity of 99.99999; 6) cooling and drying: and cooling and drying the crystalline silicon to obtain the finished crystalline silicon.

Compared with the traditional crystalline silicon production technology, the core technology of the invention is high-temperature catalysis and liquefaction purification. The crystalline silicon has the advantage of high purity, the purity of the produced crystalline silicon can reach more than 99.99999, and the efficiency of converting solar energy into electric energy of a solar photovoltaic cell made of the crystalline silicon with the high purity can reach 20-21%. The monocrystalline silicon refined by the crystalline silicon produced by the invention can beused for producing various IC chips.

Detailed Description

The present invention will be further described with reference to the following examples.

The first process step of the invention comprises: 1) feeding: the reaction crucible of the present invention adopts a jacket crucible, and the jacket mode of the jacket crucible is that a small crucible is sleeved in a large crucible, and a crack is left between the large crucible and the small crucible. When feeding, adding silicon dioxide into a small crucible of a jacketed crucible, and adding 21 percent of activated carbon and 15 percent of catalyst nickel or nickel carbonate into a crack between the large crucible and the small crucible; 2) high-temperature catalytic reaction: placing the jacketed crucible in a high-temperature furnace, performing high-temperature catalysis, controlling the temperature to be about 1650 ℃, and performing catalytic reaction until the silicon dioxide is changed into grey black to obtain primary crystalline silicon, wherein the reaction time is controlled to be about 6 hours; 3) and (3) liquefaction reaction: placing the reacted primary crystalline silicon in a closed glass container, heating to about 80 ℃, vacuumizing and reducing the pressure to about negative 1 atmospheric pressure, and introducing chlorine gas to liquefy the primary crystalline silicon into liquid silicon chloride; 4) filtering and purifying: cooling the liquid silicon chloride, then filtering, and filtering out impurities, mainly filtering out impurities such as copper, iron and the like; 5) reduction and replacement: putting the obtained filtrate into a closed glass container, introducing hydrogen at normal temperature and normal pressure, reducing, and replacing chloride ions to obtain crystalline silicon with the purity of 99.99999; 6) cooling and drying: and cooling and drying the crystalline silicon to obtain the finished crystalline silicon.

In the above process steps, the related chemical reaction process is as follows:

Si+Cl2——→SiCl4

SiCl4+2H2——→Si+4HCl

the second embodiment of the invention comprises the following process steps: 1) feeding: the reaction crucible of the present invention adopts a jacket crucible, and the jacket mode of the jacket crucible is that a small crucible is sleeved in a large crucible, and a crack is left between the large crucible and the small crucible. When feeding, adding silicon dioxide into a small crucible of a jacketed crucible, and adding active carbon accounting for 30 percent of the material amount of the silicon dioxide and catalyst nickel or nickel carbonate accounting for 16 percent of the material amount of the silicon dioxide into a crack between the large crucible and the small crucible; 2) high-temperature catalytic reaction: placing the jacketed crucible in a high-temperature furnace, performing high-temperature catalysis, controlling the temperature to be about 1680 ℃, and performing catalytic reaction until the silicon dioxide is changed into grey black to obtain primary crystalline silicon, wherein the reaction time is controlled to be about 5 hours; 3) and (3) liquefaction reaction: placing the reacted primary crystalline silicon in a sealed glass container, heating to about 85 ℃, vacuumizing and reducing the pressure to about negative 1 atmospheric pressure, and introducing chlorine gas to liquefy the primary crystalline silicon into liquid silicon chloride; 4) filtering and purifying: cooling the liquid silicon chloride, then filtering, and filtering out impurities, mainly filtering out impurities such as copper, iron and the like; 5)reduction and replacement: putting the obtained filtrate into a closed glass container, introducing hydrogen at normal temperature and normal pressure, reducing, and replacing chloride ions to obtain crystalline silicon with the purity of 99.99999; 6) cooling and drying: and cooling and drying the crystalline silicon to obtain the finished crystalline silicon.

In the above process steps, the related chemical reaction process is the same as that of the first embodiment.

The third embodiment of the invention comprises the following process steps: 1) feeding: the reaction crucible of the present invention adopts a jacket crucible, and the jacket mode of the jacket crucible is that a small crucible is sleeved in a large crucible, and a crack is left between the large crucible and the small crucible. When feeding, adding silicon dioxide into a small crucible of a jacketed crucible, and adding activated carbon with the silicon dioxide dosage of 21 percent and catalyst nickel or nickel carbonate with the silicon dioxide dosage of 12 percent into a crack between the large crucible and the small crucible; 2) high-temperature catalytic reaction: placing the jacketed crucible in a high-temperature furnace, performing high-temperature catalysis, controlling the temperature to be about 1700 ℃, and performing catalytic reaction until the silicon dioxide is changed into grey black to obtain primary crystalline silicon, wherein the reaction time is controlled to be about 6 hours; 3) and (3) liquefaction reaction: placing the reacted primary crystalline silicon in a closed glass container, heating to about 90 ℃, vacuumizing and reducing the pressure to about negative 1 atmospheric pressure, and introducing chlorine gas to liquefy the primary crystalline silicon into liquid silicon chloride; 4) filtering and purifying: cooling the liquid silicon chloride, then filtering, and filtering out impurities, mainly filtering outimpurities such as copper, iron and the like; 5) reduction and replacement: putting the obtained filtrate into a closed glass container, introducing hydrogen at normal temperature and normal pressure, reducing, and replacing chloride ions to obtain crystalline silicon with the purity of 99.99999; 6) cooling and drying: and cooling and drying the crystalline silicon to obtain the finished crystalline silicon.

It can be seen from the comprehensive examples of the first, second and third embodiments that the invention adopts the steps of high-temperature melting catalysis, impurity filtering, hydrogenation reduction and the like to obtain the crystalline silicon with the purity of more than 99.99999.

The crystalline silicon produced by the invention can be used for a solar power generation system, and the process for manufacturing the solar power generation system by using the crystalline silicon comprises the following steps: crystalline silicon- → silicon ingot, silicon wafer- → solar cell piece- → solar cell module- → solar power generation device. The monocrystalline silicon refined by the crystalline silicon produced by the invention can be used for producing various IC chips. The specific production process comprises the following steps: crystalline silicon- → refined single crystal silicon- → silicon wafer → single crystal silicon wafer- → various chips- → various IC products.

Claims

1. A method for refining and purifying crystalline silicon is characterized in that the method comprises the following process steps: 1) feeding: adding silicon dioxide into a small crucible of a jacketed crucible, and adding activated carbon with the silicon dioxide dosage of 20-30% and catalyst nickel or nickel carbonate with the silicon dioxide dosage of 10-18% into a crack between a large crucible and the small crucible; 2) high-temperature catalytic reaction: placing the jacketed crucible in a high-temperature furnace, carrying out high-temperature catalysis, controlling the temperature to be 1600-1700 ℃, and carrying out catalytic reaction until the silicon dioxide is changed into grey black to obtain primary crystalline silicon, wherein the reaction time is controlled to be about 6 hours; 3) and (3) liquefaction reaction: placing the reacted primary crystalline silicon in a closed glass container, heating to about 75-90 ℃, vacuumizing and reducing the pressure to about negative 1 atmospheric pressure, and introducing chlorine gas to liquefy the primary crystalline silicon into liquid silicon chloride; 4) filtering and purifying: cooling the liquid silicon chloride, then filtering, and filtering to remove impurities; 5) reduction and replacement: putting the obtained filtrate into a closed glass container, introducing hydrogen at normal temperature and normal pressure, reducing, and replacing chloride ions to obtain crystalline silicon with the purity of 99.99999; 6) cooling and drying: and cooling and drying the crystalline silicon to obtain the finished crystalline silicon.

2. The method for refining crystalline silicon as defined in claim 1, wherein the crucible is jacketed in such a manner that a small crucible is inserted into a large crucible with a gap left therebetween.