阅读说明：本技术 一种提高三氯氢硅品质的方法 (Method for improving quality of trichlorosilane ) 是由 官健 刘逸枫 罗轩 袁野 钟国俊 于 2021-09-30 设计创作，主要内容包括：本发明公开了一种提高三氯氢硅品质的方法,将合成精馏中提纯三氯氢硅时脱重得到的三氯氢硅重组分与四氯化硅产品液混合,依次经树脂吸附柱、反歧化树脂柱后,再作为合成精馏原料循环使用,以控制合成精馏得到的精制三氯氢硅物料中硼含量≤0.06ppb、磷含量为0.2～0.5ppb、有机硅含量为1～4ppm。本发明通过将合成精馏中循环的三氯氢硅重组分与四氯化硅混合,再进行脱硼磷等杂质处理后,再重复用于合成精馏以得到精制三氯氢硅,具有提升精制三氯氢硅及多晶硅产品质量的目的。(The invention discloses a method for improving the quality of trichlorosilane, which is characterized in that trichlorosilane recombinant obtained by de-weighting during trichlorosilane purification in synthetic rectification is mixed with silicon tetrachloride product liquid, and the mixture sequentially passes through a resin adsorption column and a reverse disproportionation resin column and then is used as a synthetic rectification raw material for recycling so as to control the boron content of the refined trichlorosilane material obtained by synthetic rectification to be less than or equal to 0.06ppb, the phosphorus content of the refined trichlorosilane material to be 0.2-0.5 ppb and the organic silicon content of the refined trichlorosilane material to be 1-4 ppm. According to the invention, trichlorosilane recombinant which circulates in the synthetic distillation is mixed with silicon tetrachloride, and is repeatedly used for synthetic distillation to obtain refined trichlorosilane after impurity treatment such as boron removal, phosphorus removal and the like, so that the purpose of improving the quality of the refined trichlorosilane and polysilicon products is achieved.)

1. A method for improving the quality of trichlorosilane is characterized by comprising the following steps: and mixing trichlorosilane recombinant obtained by de-weighting in the process of purifying trichlorosilane in the synthetic rectification with silicon tetrachloride product liquid, sequentially passing through a resin adsorption column and a reverse disproportionation resin column, and then taking the mixture as a synthetic rectification raw material for recycling so as to control the boron content to be less than or equal to 0.06ppb, the phosphorus content to be 0.2-0.5 ppb and the organic silicon content to be 1-5 ppm in the refined trichlorosilane material obtained by the synthetic rectification.

2. The method for improving the quality of trichlorosilane according to claim 1, which is characterized in that: the silicon tetrachloride product liquid is obtained by treating slag slurry from a silicon tetrachloride heavy component obtained when silicon tetrachloride is removed from the synthetic distillation.

3. The method for improving the quality of trichlorosilane according to claim 1, which is characterized in that: the trichlorosilane recombinant and silicon tetrachloride product liquid are mixed according to the weight ratio of 3-5: mixing at a volume ratio of 2 to 3.3.

4. The method for improving the quality of trichlorosilane according to claim 1, which is characterized in that: and (3) controlling the temperature of a mixed solution obtained by mixing the trichlorosilane recombinant and the silicon tetrachloride product liquid to be 60-70 ℃ through a cooler, and then sending the mixed solution into an adsorption resin column for treatment to obtain a silane material with the boron content of less than or equal to 0.3ppb and the phosphorus content of less than or equal to 1.3 ppb.

5. The method for improving the quality of trichlorosilane according to claim 4, which is characterized in that: and (3) feeding the silane material treated by the adsorption resin column into a reverse disproportionation resin column, and carrying out reverse disproportionation catalytic reaction at the temperature of 40-70 ℃ to obtain the silane material with the organic silicon content of less than or equal to 50 ppm.

6. The method for improving the quality of trichlorosilane according to claim 1, which is characterized in that: the adsorption resin column adopts a boron-removing chelating adsorption material.

7. The method for improving the quality of trichlorosilane according to claim 1, which is characterized in that: the reverse disproportionation resin column adopts a reverse disproportionation catalyst.

Technical Field

The invention belongs to the technical field of polysilicon production, and particularly relates to a method for improving the quality of trichlorosilane.

Background

With the development of the photovoltaic industry, especially the electronic industry, the requirements on the quality of polycrystalline silicon are continuously increased, and the quality of trichlorosilane serving as a main raw material directly influences the quality and yield of polycrystalline silicon products. At present, raw material manufacturers have good and uneven quality, and particularly, the content of impurities such as boron trichloride, phosphorus trichloride and the like in the raw materials is ultrahigh, so that the method has certain influence on the mass production and quality improvement of enterprises. Under the circumstances, polysilicon enterprises seek a new technical method, and expect to remove a part of impurities such as boron trichloride, phosphorus trichloride and the like by a pretreatment or post-refining method, improve and stabilize the quality of raw materials and ensure the quality of products.

The macroporous adsorption resin is used as a novel adsorption material, can selectively adsorb a target object to achieve the aim of purification and separation, has good effect on removing impurities such as boron, phosphorus and the like, and can be used as a pretreatment process for the purification of a trichlorosilane raw material. The special adsorption resin is a cross-linked functional polymer material which can form a multi-coordination complex with ions. The mechanism is that functional atoms on the resin and target ions are subjected to coordination reaction to form a stable structure similar to small molecules, the binding force with a target object is stronger, the selectivity is higher, and the method is suitable for adsorption of substances under low concentration and is mainly used for large impurity removal and refining of high-purity products. At present, through continuous efforts of part of resin enterprises, a process technology for removing impurities in trichlorosilane by using a resin treatment technology is developed, and experiments prove that accurate and detailed process technical parameters are obtained.

For example: the invention discloses an adsorption impurity removal process for ppb-level boron and phosphorus element impurities in trichlorosilane, which is disclosed by the invention with the publication number of CN105329902A, industrial trichlorosilane is rectified firstly, and then is adsorbed and removed by modified resin to remove boron and phosphorus element impurities in the trichlorosilane, so that high-purity trichlorosilane can be obtained, and the quality of a final polycrystalline silicon product can stably reach the level of an electronic grade.

However, in the production process of polysilicon, the main sources of boron and phosphorus impurities are carried in by hydrogen and hydrogen chloride and a small amount of equipment besides industrial silicon powder. The boron-phosphorus impurities in the silicon powder participate in the reaction in the trichlorosilane synthetic furnace and the cold hydrogenation furnace to form boron-phosphorus compounds and methyl silane which exist in the trichlorosilane liquid and can be removed through multi-stage rectification, but in a high-purity rectification system, the boron, the phosphorus and the methyl silane which are light and heavy components are still not easy to be completely removed. The impurities which participate in material circulation in the system enter the rectification unit along with the materials, finally enter the reduction process, then enter the recovery rectification unit along with the reduction tail gas, and finally form an impurity circulation accumulation.

In the prior art, in order to solve the problem of removing impurities such as boron, phosphorus, methyl silane and the like in a high-purity rectification system, the invention patent with publication number of CN103553058A discloses a production process of high-purity refined trichlorosilane, which combines adsorption and rectification processes, wherein after the impurities in crude trichlorosilane are adsorbed by resin, silicon tetrachloride, dichlorosilane, trichlorosilane and hydrogen chloride in the crude trichlorosilane are separated by rectification, and the purity of the trichlorosilane obtained by rectification is more than 99.9999%. In addition, the invention patent with publication number CN109205627A discloses a device and a method for preparing high-purity trichlorosilane by adsorbing and removing methyl chlorosilane impurities, trichlorosilane after multistage rectification is used as an adsorption raw material, a directional adsorbent is used for carrying out fractional adsorption on methyl chlorosilane impurities, and the adsorbed trichlorosilane material can be directly used as a raw material of a reduction process without rectification.

Disclosure of Invention

The invention aims to provide a method for improving the quality of trichlorosilane, which has the aim of improving the quality of refined trichlorosilane and polysilicon products by mixing trichlorosilane heavy components circulating in synthetic rectification with silicon tetrachloride, carrying out impurity treatment such as boron and phosphorus removal and the like, and then repeatedly using the mixture for synthetic rectification to obtain the refined trichlorosilane.

The invention is realized by the following technical scheme: the method for improving the quality of trichlorosilane comprises the steps of mixing trichlorosilane recombinant obtained by de-weighting in trichlorosilane purification in synthetic rectification with silicon tetrachloride product liquid, sequentially passing through a resin adsorption column and a reverse disproportionation resin column, and then taking the mixture as a synthetic rectification raw material for recycling, so as to control the boron content of the refined trichlorosilane material obtained by synthetic rectification to be less than or equal to 0.06ppb, the phosphorus content of the refined trichlorosilane material to be 0.2-0.5 ppb and the organic silicon content of the refined trichlorosilane material to be 1-5 ppm.

The silicon tetrachloride product liquid is obtained by treating slag slurry from a silicon tetrachloride heavy component obtained when silicon tetrachloride is removed from the synthetic distillation.

The trichlorosilane recombinant and silicon tetrachloride product liquid are mixed according to the weight ratio of 3-5: mixing at a volume ratio of 2 to 3.3.

And (3) controlling the temperature of a mixed solution obtained by mixing the trichlorosilane recombinant and the silicon tetrachloride product liquid to be 60-70 ℃ through a cooler, and then sending the mixed solution into an adsorption resin column for treatment to obtain a silane material with the boron content of less than or equal to 0.3ppb and the phosphorus content of less than or equal to 1.3 ppb.

And (3) feeding the silane material treated by the adsorption resin column into a reverse disproportionation resin column, and carrying out reverse disproportionation catalytic reaction at the temperature of 40-70 ℃ to obtain the silane material with the organic silicon content of less than or equal to 50 ppm.

The adsorption resin column adopts a boron-removing chelating adsorption material.

The reverse disproportionation resin column adopts a reverse disproportionation catalyst.

Compared with the prior art, the invention has the following advantages and beneficial effects:

(1) according to the invention, a mode of matching treatment of the resin adsorption column and the anti-disproportionation resin column is adopted, impurities such as boron, phosphorus and the like and organic silicon in the material can be removed to a great extent, the content of phosphorus in the treated material is less than or equal to 0.3ppb, the content of phosphorus is less than or equal to 1.3ppb, and the content of organic silicon is less than or equal to 50ppm, the treated material is used as a raw material for synthetic rectification, the content of the impurities for refining trichlorosilane in the synthetic rectification can be obviously reduced through the circulating operation of the system, the content of boron in the material is controlled to be less than or equal to 0.06ppb, the content of phosphorus in the material is controlled to be 0.2-0.5 ppb, and the content of organic silicon in the material is controlled to be 1-5 ppm, so that the quality of trichlorosilane is improved.

(2) The resin adsorption column is adopted to effectively remove boron-phosphorus hybrid compounds mainly existing in a silane system by utilizing the chemical adsorption reaction characteristic of catalytic resin, so that the content of the boron-phosphorus hybrid compounds is greatly reduced, the boron-phosphorus hybrid compounds are used as an important device link for removing impurities of the system to effectively reduce the impurity equilibrium concentration in the system, and then the aim of improving the quality of trichlorosilane refined materials and polycrystalline silicon products is fulfilled, the resin adsorption temperature is controlled to be 60-70 ℃, and the ideal reaction temperature of the catalytic resin can be achieved.

(3) The invention can remove the organic silicon impurities in the materials through the catalytic reaction characteristic of the anti-disproportionation catalyst. In order to ensure the effective proceeding of the anti-disproportionation catalytic reaction, silicon tetrachloride product liquid and trichlorosilane heavy components in proper proportion can be mixed, excessive reaction of TCS and resin can be inhibited by adding STC, and the condition of over-temperature and over-pressure in the reaction process is avoided. Meanwhile, the anti-disproportionation catalysis temperature is controlled to be 40-70 ℃, so that the reaction of the catalytic resin can be facilitated, and the maximum adsorption reaction capability can be exerted.

In conclusion, the method can effectively reduce the impurity content of the trichlorosilane heavy component in the original synthetic rectification by adding the anti-disproportionation catalysis and the resin adsorption treatment in the synthetic rectification system, and can also effectively reduce the impurity equilibrium concentration in the synthetic rectification system, thereby achieving the purpose of improving the quality of the refined trichlorosilane and polycrystalline silicon products.

Drawings

FIG. 1 is a schematic process flow diagram of the present invention.

Detailed Description

The objects, technical solutions and advantageous effects of the present invention will be described in further detail below.

It is to be noted that the following detailed description is exemplary and is intended to provide further explanation of the invention claimed, and unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs.

In the production process of high-purity polysilicon, the content of impurities such as boron, phosphorus and the like in the product needs to be strictly controlled in a mode of impurity removal and refining. The impurities mainly come from the silicon powder, hydrogen and hydrogen chloride, and also include a small amount of the impurities from the equipment. Although the purity of polysilicon raw material gas can be improved to a certain extent by the existing impurity removal and refining modes, with the continuous production of a polysilicon production system, impurities brought by silicon powder, hydrogen chloride and equipment are continuously and circularly accumulated in the polysilicon system, so that the equilibrium concentration of the impurities in the system is increased, and the product quality of high-purity polysilicon is reduced. In order to solve the problem of product quality reduction caused by increased impurity equilibrium concentration in the system, the invention needs to find a method capable of reducing the impurity equilibrium concentration of a polycrystalline silicon system, and the method not only can obtain high-quality trichlorosilane and polycrystalline silicon products, but also can continuously control the impurity equilibrium concentration of the system in the continuous operation process of the polycrystalline silicon system, thereby achieving the purpose of improving the quality of the trichlorosilane and polycrystalline silicon products.

The following examples are provided to illustrate specific embodiments of the present invention, and it is understood that the scope of the present invention is not limited to the following examples.

Example 1:

the embodiment is a method for improving the quality of trichlorosilane, and mainly comprises a reverse disproportionation resin column and a resin adsorption column which are additionally arranged in a synthetic rectification system. FIG. 1 includes the synthetic rectification process flow and the resin adsorption column and the inverse disproportionation resin column of this example. The synthetic rectification process flow comprises a synthetic rectification raw material tank, a synthetic rectification 1-stage tower, a synthetic rectification 2-stage tower, a synthetic rectification 3-stage tower, a synthetic rectification 4-stage tower, a synthetic rectification 5-stage tower and a synthetic rectification 6-stage tower.

When in use, the synthesized and cold hydrogenated product liquid is sent to a synthetic rectification raw material tank (V9101) and then enters a synthetic rectification 1-level tower for separation, STC is extracted from the tower kettle, and TCS and DCS are extracted from the tower top. STC obtained by separation and STC separated by a slurry evaporator (807-3 and 807-4) enter a synthetic rectification 6-grade tower together for height removal, heavy components and metal impurities are extracted from a tower kettle and conveyed to 807-4 for slurry treatment, and STC (silicon tetrachloride product liquid) meeting the product quality requirement is extracted from the tower top for cold hydrogenation and anti-disproportionation processes.

The TCS and the DCS which are extracted from the top of the synthetic rectification 1-stage tower enter a synthetic rectification 2-stage tower for separation, the DCS is extracted from the top of the synthetic rectification 2-stage tower and sent to an anti-disproportionation process, and the TCS is extracted from the synthetic rectification 2-stage tower kettle and then enters a synthetic rectification 3-stage tower, a synthetic rectification 4-stage tower and a synthetic rectification 5-stage tower in sequence for purification. Wherein, the synthetic rectification 3-stage tower is used for removing the weight, the synthetic rectification 4-stage tower is used for removing the light, the synthetic rectification 5-stage tower is used for removing the weight again, the obtained refined TCS is extracted from the top of the synthetic rectification 5-stage tower and is conveyed to a finished product storage tank to be used as a reduced raw material for production.

And mixing the trichlorosilane heavy components extracted from the synthetic rectification 3-level tower kettle and the synthetic rectification 5-level tower kettle with the silicon tetrachloride product liquid after the slag slurry treatment according to the weight ratio of 3-5: 2-3.3, controlling the temperature to be 60-70 ℃ through a cooler, sending the mixture into an adsorption resin column for treatment, then controlling the temperature of the treated silane material to be 40-70 ℃, sending the silane material into a reverse disproportionation resin column for reverse disproportionation catalytic reaction, and returning the obtained silane material to V9101 for recycling.

When the adsorption resin is treated, a boron removal chelating adsorption material can be adopted, and the parameters of the boron removal chelating adsorption material meet the following conditions:

(1) appearance: spherical particles, no resin particles are damaged or deformed;

(2) water content: dry basis <1.2wt%, wet basis 48-54 wt%;

(3) exchange capacity: not less than 3.5mmol/g

(4) Particle size: 0.315-1.26 mm (50-14 mesh);

(5) maximum operating temperature: less than or equal to 50 ℃;

(6) pH value: 0 to 14.

In the catalytic reaction of the disproportionation, a catalyst of disproportionation can be used, and the parameters thereof satisfy the following conditions:

(1) appearance: the opaque spherical particles are free from any material particle breakage and deformation;

(2) water content: dry basis <1.0 wt%;

(3) the main components are as follows: weakly basic polymeric resins, free base;

(4) exchange capacity: the total exchange capacity is more than or equal to 5mmol/g, and the volume exchange capacity is more than or equal to 1.4 mmol/ml;

(5) particle size: average value of 0.4-0.7mm, uniformity coefficient of less than or equal to 1.8, fine particle content (< 0.3 mm) of less than or equal to 1.0%, coarse particle content (< 1.18 mm) of less than or equal to 2%;

(6) maximum operating temperature: 120 ℃;

(7) pH value: 0 to 14;

(8) bulk density: 0.3-0.35 g/ml;

(9) specific surface area: every gram of square meter;

(10) total pore volume: 0.1cc/g, average pore diameter: 110A.

During specific implementation, regulating valves of trichlorosilane heavy components and silicon tetrachloride product liquid are preset according to an automatic control program, and the set range is controlled to be the volume ratio. During temperature control, the temperature sensor is adopted to measure the temperature of the material and feed the temperature back to the computer so as to adjust the temperature medium of the cooler through an automatic control program, and the adjusting range is controlled within the temperature range.

Example 2:

the resin adsorption column and the inverse disproportionation resin column in the embodiment 1 are added on the existing synthesis and rectification process system, and meanwhile, facilities such as a matched cooler, an instrument, a pipeline, a valve and the like are arranged. The investment budget table is shown in table 1 below.

TABLE 1 investment budget List

The embodiment predicts the total investment of 53 ten thousand yuan, wherein the equipment cost is 40 ten thousand yuan, and the supporting facilities are 13 ten thousand yuan.

In this embodiment, according to the process flow described in example 1, after installation and debugging, the resin starts to be put into operation after being dried and activated, the product qualities of the trichlorosilane heavy component, the silicon tetrachloride product liquid, the refined trichlorosilane material and the polysilicon before and after operation (30 days/180 days) are respectively sampled and detected, and the detection data are shown in tables 2, 3, 4 and 5 below.

TABLE 2 System Material sampling test data before operation

TABLE 3 System Material sampling test data 30 days after operation

TABLE 4 System Material sampling test data 180 days after operation

TABLE 5 polysilicon product sampling test data before and after operation

The above description is only a preferred embodiment of the present invention, and is not intended to limit the present invention in any way, and all simple modifications and equivalent variations of the above embodiments according to the technical spirit of the present invention are included in the scope of the present invention.