阅读说明：本技术 一种使用异常原料生产单晶硅的方法 (Method for producing monocrystalline silicon by using abnormal raw materials ) 是由 李立峰 胡海勇 曹森 侯雨 关鹏羽 曲雁鹏 陈朝霞 于 2019-04-25 设计创作，主要内容包括：本发明提供一种使用异常原料生产单晶硅的方法,包括装料：将多晶硅原料和异常原料混装在坩埚中；化料：将异常原料和多晶硅原料熔化；杂质提出：在化料后期将所述坩埚内未熔化的多晶硅异常原料提出；生长：利用籽晶将提出杂质后剩余的硅熔体提拉以获得单晶硅。本发明所述的使用异常原料生产单晶硅的方法,通过对单晶硅生产过程中步骤及参数的改变,实现了将含杂质多、品质较差的多晶硅原料分离提出,解决了使用品质较差的多晶硅原料生产过程中单晶硅品质无法保证的问题,使单晶硅生产成本大大降低,同时提高生产效率、提升产品品质。(The invention provides a method for producing monocrystalline silicon by using abnormal raw materials, which comprises the following steps: mixing polycrystalline silicon raw materials and abnormal raw materials in a crucible; material melting: melting the abnormal raw material and the polycrystalline silicon raw material; and (3) impurity extraction: extracting unmelted polycrystalline silicon abnormal raw materials in the crucible in the later stage of material melting; growing: pulling up the silicon melt remaining after the extraction of impurities by using a seed crystal to obtain single-crystal silicon. The method for producing the monocrystalline silicon by using the abnormal raw materials realizes separation and extraction of polycrystalline silicon raw materials with more impurities and poorer quality by changing steps and parameters in the production process of the monocrystalline silicon, solves the problem that the quality of the monocrystalline silicon cannot be ensured in the production process of the polycrystalline silicon raw materials with poorer quality, greatly reduces the production cost of the monocrystalline silicon, improves the production efficiency and improves the product quality.)

1. A method of producing single crystal silicon using an abnormal raw material, comprising the steps of:

charging: mixing polycrystalline silicon raw materials and abnormal raw materials in a crucible;

material melting: melting the abnormal raw material and the polycrystalline silicon raw material;

and (3) impurity extraction: in the later stage of melting, extracting the raw material containing impurity part which is not melted in the crucible;

growing: pulling up the silicon melt remaining after the extraction of impurities by using a seed crystal to obtain single-crystal silicon.

2. The method for producing single-crystal silicon using abnormal raw materials as claimed in claim 1, wherein the weight ratio of the polycrystalline silicon raw material to the abnormal raw materials during the charging is X:1, wherein 1. ltoreq. X.ltoreq.3.

3. The method for producing single-crystal silicon using abnormal raw material as set forth in claim 1 or 2, wherein during the charging, polycrystalline silicon raw material is placed near the side wall of the crucible, and abnormal raw material is placed in the crucible in the middle surrounded by the polycrystalline silicon raw material.

4. The method for producing single-crystal silicon using an abnormal raw material as claimed in claim 1, wherein the melting step is divided into the following three stages:

in the initial stage of material melting: the material melting power is operated according to the set power, the range of the set power is 40-100KW, and the rotating speed of the crucible is set to be 1-2 r/min;

In the middle stage of material melting: after the melting is started for 1-4h, the melting power reaches the peak value, the peak power is controlled to be 50-130KW, the duration is 5-15h, and the rotating speed of the crucible is set to be 1-2 r/min;

and (3) material melting later stage: after the size of the raw materials in the crucible is melted to 80-120mm, the material melting power is reduced to the seeding power, and the rotating speed of the crucible is increased to 3-7 r/min.

5. The method for producing single-crystal silicon using an abnormal raw material according to claim 4, wherein the material melting step further comprises the steps of:

argon is filled in the whole material melting process as protective gas, the pressure in the cavity of the single crystal furnace is controlled to be 0.5kPa-8kPa, and the flow of the argon is controlled to be 10-150L/min.

6. The method for producing single-crystal silicon using an abnormal raw material as claimed in claim 1, wherein the impurity extracting step includes:

and after the size of the raw material in the crucible is melted to 80-120mm, reducing the power of a heater for melting the material to the seeding power, setting the rotating speed of the crucible to be 3-7 r/min, extracting the unmelted abnormal raw material in the crucible as impurities by using the old seed crystals, and controlling the rotating speed of the crucible to be 8-10 r/min after the impurities are extracted.

7. The method for producing single-crystal silicon using an abnormal raw material as claimed in claim 1, wherein the growing step is divided into the following five stages:

And (3) stabilizing: adjusting the power of a heater for melting materials to be conventional melting material power, setting the rotating speed of a crucible to be 5-8 r/min, and setting the duration of the stabilizing process to be 0.15-0.7 times of the duration of the whole melting material process;

seeding: controlling the seeding length to be 1-3 times of the diameter of the drawn crystal, and controlling the diameter of the thin neck within 4mm +/-0.5 mm;

shouldering: a slow-drawing and shoulder-laying mode is adopted, and the taper of the shoulder shape is controlled to be 120-150 degrees;

and (3) constant-diameter production: controlling the equal-diameter production of the crystal to the required length;

ending: the length of the tail is controlled to be 0.2-2 times of the diameter of the crystal, and the diameter of the section of the tail is less than or equal to 120 mm.

8. The method for producing single crystal silicon using an abnormal raw material according to claim 7, wherein the growing step further comprises: argon is filled in the whole growth process as protective gas, the pressure in the cavity of the single crystal furnace is controlled to be 1kPa-4kPa, and the flow of the argon is controlled to be 30-50L/min.

9. The method of producing single crystal silicon using anomalous starting materials in accordance with claim 7 wherein the weight of the residue in the crucible after said growing step is completed is between 1% and 2.5% of the total weight of the charge.

Technical Field

The invention relates to the technical field of monocrystalline silicon, in particular to a method for producing monocrystalline silicon by using abnormal raw materials

Background

The Czochralski method (hereinafter referred to as "CZ method") is currently the most commonly employed for the production of single-crystal silicon. The single-crystal silicon is obtained by charging a crucible with a polycrystalline silicon raw material, melting the polycrystalline silicon in the crucible using a thermal field to obtain a silicon melt, then bringing a seed crystal into contact with the silicon melt, and pulling the seed crystal. The specific process for producing the silicon single crystal rod comprises the following steps: the method comprises the steps of loading and melting, welding, necking, shouldering, shoulder rotating, equal-diameter growth, ending and the like, wherein the purity of monocrystalline silicon is required to reach 99.9999 percent, even more than 99.9999999 percent, the production process is strictly controlled, the quality of the produced polycrystalline silicon raw material is also required to be high, but the cost of the high-purity polycrystalline silicon raw material is high, the polycrystalline silicon raw material is produced along with different degraded polycrystalline silicon raw materials, and the qualified polycrystalline silicon raw material is simply used for production, so that the production cost of the monocrystalline silicon is high.

Therefore, it is important to reduce the production cost while ensuring the intrinsic quality of the silicon ingot.

Disclosure of Invention

The present invention has been made to solve, at least in part, the technical problems of the prior art that the production cost is high and that the silicon single crystal cannot be produced using an abnormal raw material.

The technical scheme adopted for solving the technical problem of the invention is as follows:

the invention provides a method for producing monocrystalline silicon by using abnormal raw materials, which comprises the following steps:

charging: mixing polycrystalline silicon raw materials and abnormal raw materials in a crucible;

material melting: melting the abnormal raw material and the polycrystalline silicon raw material;

and (3) impurity extraction: in the later stage of melting, extracting the raw material containing impurity part which is not melted in the crucible;

growing: pulling up the silicon melt remaining after the extraction of impurities by using a seed crystal to obtain single-crystal silicon.

According to the method for producing the monocrystalline silicon by using the abnormal raw materials, the unmelted abnormal polycrystalline silicon raw materials in the later stage of material melting are extracted in the crystal pulling process, so that the polycrystalline silicon raw materials with high impurity content and poor quality are separated and extracted, the crystal quality after crystal pulling is improved, and the crystal pulling yield is improved.

Further, in the charging process, the weight ratio of the polycrystalline silicon raw material to the abnormal raw material is X:1, wherein X is more than or equal to 1 and less than or equal to 3.

Further, during the charging process, polycrystalline silicon feedstock is placed adjacent the sidewall of the crucible and an anomalous feedstock is placed within the crucible in the middle of the crucible surrounded by polycrystalline silicon feedstock.

Further, the material melting step is divided into the following three stages:

in the initial stage of material melting: the material melting power is operated according to the set power, the range of the set power is 40-100KW, and the rotating speed of the crucible is set to be 1-2 r/min;

in the middle stage of material melting: after the melting is started for 1-4h, the melting power reaches the peak value, the peak power is controlled to be 50-130KW, the duration is 5-15h, and the rotating speed of the crucible is set to be 1-2 r/min;

and (3) material melting later stage: after the size of the raw materials in the crucible is melted to 80-120mm, the material melting power is reduced to the seeding power, and the rotating speed of the crucible is increased to 3-7 r/min.

Further, the material melting step also comprises the following steps:

argon is filled in the whole material melting process as protective gas, the pressure in the cavity of the single crystal furnace is controlled to be 0.5kPa-8kPa, and the flow of the argon is controlled to be 10-150L/min.

Further, the impurity extracting step includes:

and after the size of the raw material in the crucible is melted to 80-120mm, reducing the power of a heater for melting the material to the seeding power, setting the rotating speed of the crucible to be 3-7 r/min, extracting the unmelted abnormal raw material in the crucible as impurities by using the old seed crystals, and controlling the rotating speed of the crucible to be 8-10 r/min after the impurities are extracted.

Further, the growth step is divided into the following five stages:

and (3) stabilizing: adjusting the power of a heater for melting materials to be conventional melting material power, setting the rotating speed of a crucible to be 5-8 r/min, and setting the duration of the stabilizing process to be 0.15-0.7 times of the duration of the whole melting material process;

seeding: controlling the seeding length to be 1-3 times of the diameter of the drawn crystal, and controlling the diameter of the thin neck within 4mm +/-0.5 mm;

shouldering: a slow-drawing and shoulder-laying mode is adopted, and the taper of the shoulder shape is controlled to be 120-150 degrees;

and (3) constant-diameter production: controlling the equal-diameter production of the crystal to the required length;

ending: the length of the tail is controlled to be 0.2-2 times of the diameter of the crystal, and the diameter of the section of the tail is less than or equal to 120 mm.

Further, the growing step further comprises: argon is filled in the whole growth process as protective gas, the pressure in the cavity of the single crystal furnace is controlled to be 1kPa-4kPa, and the flow of the argon is controlled to be 30-50L/min.

Further, after the growing step is completed, the weight of the residual materials in the crucible is 1-2.5% of the total weight of the materials.

Has the advantages that:

according to the method for producing the monocrystalline silicon by using the abnormal raw materials, the polycrystalline silicon raw materials with more impurities and poorer quality are separated and extracted by changing the steps and parameters in the production process of the monocrystalline silicon, the problem that the quality of the monocrystalline silicon cannot be ensured in the production process of the polycrystalline silicon raw materials with poorer quality is solved, the production cost of the monocrystalline silicon is greatly reduced, the production efficiency is improved, and the product quality is improved.

Drawings

FIG. 1 is a flow chart of a method for producing single crystal silicon using an abnormal raw material according to an embodiment of the present invention.

Detailed Description

In order to make the technical solutions of the present invention better understood, the present invention is further described in detail below with reference to the accompanying drawings and examples.

As shown in fig. 1, the present invention provides a method for producing single crystal silicon using abnormal raw materials, including the following steps S1 to S4.

S1, charging: mixing a polycrystalline silicon raw material and an abnormal raw material in a quartz crucible;

s2, material melting: melting the abnormal raw material and the polycrystalline silicon raw material;

s3, impurity extraction: in the later stage of melting, extracting the raw material containing impurity part which is not melted in the crucible;

s4, growing: and pulling the silicon melt left after the impurities are extracted by using the seed crystal to obtain the single crystal silicon.

The CZ monocrystalline silicon production method is characterized by that in a straight-tube type thermal system it uses graphite resistance to heat, and melts the polycrystalline silicon placed in high-purity quartz crucible, then inserts the seed crystal into the surface of melt to make fusion-connection, at the same time, rotates the seed crystal, and reverses the crucible, and the seed crystal is slowly lifted upwards, and passed through the processes of seeding, amplifying, shoulder-rotating, isometric growth and ending so as to obtain the monocrystalline silicon. The quality of the polysilicon raw material is crucial to the quality of the finished product of the monocrystalline silicon, but the cost of the high-quality polysilicon is higher, in the production process of the polycrystalline silicon, along with the production of polycrystalline silicon of multiple grades, polycrystalline silicon raw materials with different degradation and low price are called abnormal polycrystalline silicon raw materials, which are called abnormal raw materials for short, and the abnormal raw materials contain more impurities, and the surface of the polysilicon can be contaminated with residual impurities, which can cause serious influence on the parameters of the produced monocrystalline silicon, when abnormal raw materials are used for producing the monocrystalline silicon, a special process is needed to be used for treating the polycrystalline silicon after melting in the production process, impurities are extracted, in order to meet the quality requirement of monocrystalline silicon production, abnormal raw materials and qualified polycrystalline silicon raw materials are put into a crucible according to a certain proportion in the charging process of the embodiment of the invention, and the raw materials need to be compactly stacked during charging, and the sharp part can not be over against the inner wall of the quartz crucible; the raw materials in the crucible reach the molten state under the heating of thermal field, melt the later stage at polycrystalline silicon raw materials and unusual raw materials, utilize the characteristics of melting behind the impurity in the unusual raw materials, reduce heating power, utilize old seed crystal to refine impurity out, then will refine the raw materials of impurity and produce monocrystalline silicon, when containing impurity in the polycrystalline silicon raw materials of course, because the characteristics that the impurity melting point is higher, also can utilize the characteristic that the solid easily proposed to propose impurity with the impurity, promote the quality of monocrystalline silicon.

Further, in the charging process, the weight ratio of the polycrystalline silicon raw material to the abnormal raw material is X:1, wherein X is more than or equal to 1 and less than or equal to 3.

In the process of filling raw materials, qualified polycrystalline silicon raw materials and abnormal raw materials are put into a crucible according to a certain weight proportion, the proportion of the abnormal raw materials is determined according to the grade of the used abnormal raw materials, the abnormal raw materials with lower grade contain more impurities and the input proportion is smaller, and the polycrystalline silicon raw materials and the abnormal raw materials are generally controlled according to the ratio X to 1, wherein X is more than or equal to 1 and less than or equal to 3.

Further, during the charging process, polycrystalline silicon feedstock is placed adjacent the sidewall of the crucible and an anomalous feedstock is placed within the crucible in the middle of the crucible surrounded by polycrystalline silicon feedstock. The method comprises the steps of heating a single crystal silicon furnace, heating the crucible by a graphite thermal field around the crucible, placing qualified polycrystalline silicon raw materials at the inner wall close to the edge of the quartz crucible, placing abnormal raw materials in the middle of the quartz crucible, preferentially melting the raw materials at the edge of the crucible during material melting, subsequently melting the raw materials at the middle part and the top part of the quartz crucible, placing the qualified polycrystalline silicon raw materials at the inner wall close to the edge of the quartz crucible, placing the abnormal raw materials in the middle of the quartz crucible, melting the abnormal polycrystalline silicon raw materials containing impurities and poor quality at the final stage by controlling the power of the melting materials, the rotating speed of the crucible, the flow of argon gas and the pressure in a single crystal furnace body, and then extracting the impurities and non-melting substances in the molten polycrystalline silicon raw materials in the impurity.

Further, the material melting step is divided into the following three stages:

in the initial stage of material melting: the material melting power is operated according to the set power, the range of the set power is 40-100KW, and the rotating speed of the crucible is set to be 1-2 r/min;

in the middle stage of material melting: after the melting is started for 1-4h, the melting power reaches the peak value, the peak power is controlled to be 50-130KW, the duration is 5-15h, and the rotating speed of the crucible is set to be 1-2 r/min;

and (3) material melting later stage: after the size of the raw materials in the crucible is melted to 80-120mm, the material melting power is reduced to the seeding power, and the rotating speed of the crucible is increased to 3-7 r/min.

After the materials are loaded, according to the specification of the single crystal furnace, the crucible is heated according to the set power, the crucible is slowly rotated, the material melting power of a thermal field in the single crystal furnace is increased along with the heating, the temperature of polycrystalline silicon in the crucible is increased to be above a melting point, the polycrystalline silicon raw materials begin to melt, when the raw materials in the crucible are melted to 80-120mm, the power of the thermal field is reduced to seeding power, the rotating speed is controlled to be 3-7 revolutions, and the impurities are conveniently extracted at the moment.

Further, the material melting step also comprises the following steps:

argon is filled in the whole material melting process as protective gas, the pressure in the cavity of the single crystal furnace is controlled to be 0.5kPa-8kPa, and the flow of the argon is controlled to be 10-150L/min. Introducing argon to remove impurities and reaction product gases, such as CO, CO2, O2, SiO and the like, and controlling the pressure in the furnace through a vacuum pump throttle valve.

Further, the impurity extracting step includes:

and after the size of the raw material in the crucible is melted to 80-120mm, reducing the power of a heater for melting the material to the seeding power, setting the rotating speed of the crucible to be 3-7 r/min, extracting the unmelted abnormal raw material in the crucible as impurities by using the old seed crystals, and controlling the rotating speed of the crucible to be 8-10 r/min after the impurities are extracted.

In the later stage of the material melting process, by observing the melting condition of the raw materials in the crucible, after the raw materials are melted to 80-120mm, reducing the power of a main heater and increasing the rotation speed of the crucible to rapidly crystallize the surface of the liquid level, extracting the unmelted abnormal polycrystalline silicon raw materials in the crucible by adopting old seed crystals, observing the impurity condition of the liquid level, finishing the extraction of the impurities after the impurities are not visible to the naked eye on the liquid level, and increasing the rotation speed of the crucible to 8-10 r/min to mix the melt.

Further, the growth step is divided into the following five stages:

and (3) stabilizing: adjusting the power of a heater for melting materials to be conventional melting material power, setting the rotating speed of a crucible to be 5-8 r/min, and setting the duration of the stabilizing process to be 0.15-0.7 times of the duration of the whole melting material process;

seeding: controlling the seeding length to be 1-3 times of the diameter of the drawn crystal, and controlling the diameter of the thin neck within 4mm +/-0.5 mm;

Shouldering: a slow-drawing and shoulder-laying mode is adopted, and the taper of the shoulder shape is controlled to be 120-150 degrees;

and (3) constant-diameter production: controlling the equal-diameter production of the crystal to the required length;

ending: the length of the tail is controlled to be 0.2-2 times of the diameter of the crystal, and the diameter of the section of the tail is less than or equal to 120 mm.

After impurities are extracted, the power of a heater is adjusted to be the power of a conventional material melting device, the rotating speed of a crucible is controlled to be restored to the normal rotating speed, the stability of the polycrystalline silicon solution is maintained, after the solution is stabilized, new seed crystals are used for liquid level contact, the temperature is used for controlling seeding and shouldering, the diameter is amplified through the adjustment of the temperature and drawing, after the solution is amplified to a proper size, the diameter is subjected to equal-diameter growth, finally ending is carried out, and after the required length is reached, the diameter of a crystal rod is subjected to necking.

Further, the growing step further comprises: argon is filled in the whole growth process as protective gas, the pressure in the cavity of the single crystal furnace is controlled to be 1kPa-4kPa, and the flow of the argon is controlled to be 30-50L/min.

The filling amount and flow rate of argon can be kept constant during the solution stabilization process, and the flow rate of argon can be properly reduced after the seeding process is started.

Further, after the growing step is completed, the weight of the residual materials in the crucible is 1% -2.5% of the total weight of the charging materials.

After finishing the ending, the residual polycrystalline silicon raw material in the crucible accounts for 1-2.5% of the total weight of the charge, the residual weight in the crucible is determined according to the quality of the raw material and the operation in the crystal pulling process and can be 1.5%, 2%, 2.3% and the like of the total weight of the charge, and the residual amount is cleaned up after the production is finished.

In order to better describe the technical solution of the present disclosure, the following describes in detail a specific process of a preferred embodiment of the present invention, and the steps of the embodiment include:

charging: the polycrystalline silicon raw material and the abnormal raw material are mixed according to the weight ratio of 2: 1 in a proportion of 1, the qualified polycrystalline silicon raw material is arranged at a position close to the side wall of the quartz crucible, the abnormal raw material of the secondary polycrystalline silicon is arranged in the middle of the quartz crucible, and the raw material is compactly piled up and the sharp part is not aligned to the inner wall of the quartz crucible in the charging process;

material melting:

when the material melting is started, the material melting power of the heater is operated according to 100kW, and the rotating speed of the quartz crucible is 1 r/min of the conventional rotating speed;

3 hours after the melting is started, the melting power reaches the peak value of 110KW, and the rotating speed of the quartz crucible lasts for 10 hours at 2 revolutions per minute;

and (3) impurity extraction: when the polycrystalline silicon raw material is molten to about 100mm, reducing the heating power to the seeding power, and controlling the crucible rotation speed to be 5 r/min to crystallize the surface of the liquid surface, then extracting impurities from the seed crystal polycrystalline silicon raw material, and adjusting the crucible rotation speed to be 9 r/min for 5h after the impurities are extracted;

In the whole material melting process, argon exists as protective gas, the pressure in the furnace is controlled to be 1kPa-4kPa by a vacuum pump through the opening of a throttle valve, and the flow is controlled to be 50-70L/min;

and (3) stabilizing: adjusting the power of a heater to seeding power, adjusting the rotating speed of a quartz crucible to 5 revolutions per minute, adjusting the flow of argon to 30L per minute, adjusting the pressure in a single crystal furnace to 1.5kPa, and stabilizing for 6 hours;

seeding: the seeding length is 1-3 times of the crystal diameter during seeding, and the diameter of the thin neck is controlled to be 4mm +/-0.5 mm;

during shouldering, a slow-pulling shouldering mode is carried out, and the taper of the shoulder shape is controlled to be 120-150 degrees;

and (3) constant-diameter production: controlling the equal-diameter production of the crystal to the required length;

ending: the length of the tail part is 0.5 times of the length and the diameter of the crystal during ending, the diameter of the section of the tail part is less than or equal to 10mm, and the mass of the residual materials in the quartz crucible after ending is 1.2-2.3% of the total weight of the materials in the step one.

It will be understood that the above embodiments are merely exemplary embodiments taken to illustrate the principles of the present invention, which is not limited thereto. It will be apparent to those skilled in the art that various modifications and improvements can be made without departing from the spirit and substance of the invention, and these modifications and improvements are also considered to be within the scope of the invention.