WO2024131427A1

WO2024131427A1 - Silicon material melting method, monocrystalline silicon rod drawing method, and monocrystalline silicon rod drawing apparatus

Info

Publication number: WO2024131427A1
Application number: PCT/CN2023/133228
Authority: WO
Inventors: 韩伟; 邓浩
Original assignee: 隆基绿能科技股份有限公司
Priority date: 2022-12-23
Filing date: 2023-11-22
Publication date: 2024-06-27
Also published as: CN116200811A

Abstract

Provided in the embodiments of the present application are a silicon material melting method, a monocrystalline silicon rod drawing method and a monocrystalline silicon rod drawing apparatus. The silicon material melting method comprises: providing a furnace, wherein a crucible and a heater are mounted in the furnace; putting a silicon material in the crucible; adjusting the furnace pressure in the furnace to a first preset range at a first preset rate; adjusting the power of the heater to a second preset range at a second preset rate, so as to heat the silicon material in the crucible; and maintaining the furnace pressure and the power for a first preset duration until the silicon material is melted into silicon liquid. In the embodiments of the present application, the inhibition of a hydrogen jump phenomenon is conducive to the large-scale application of granules, thereby reducing the raw material cost and production cost of monocrystalline silicon rods.

Description

Silicon material melting method, single crystal silicon rod drawing method and single crystal silicon rod drawing device

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority to a Chinese patent application filed with the Chinese Patent Office on December 23, 2022, with application number 202211670780.1 and titled “Silicon Material Melting Method, Single Crystal Silicon Rod Pulling Method and Single Crystal Silicon Rod Pulling Device,” the entire contents of which are incorporated by reference into this application.

Technical Field

The present application belongs to the field of photovoltaic technology, and specifically relates to a silicon material melting method, a single crystal silicon rod drawing method and a single crystal silicon rod drawing device.

Background technique

In recent years, photovoltaic power generation, as a green energy and a major energy source for sustainable human development, has been increasingly valued and developed by countries around the world. As a basic material for photovoltaic power generation, single crystal silicon wafers have a wide market demand. Single crystal silicon wafers are usually obtained by slicing single crystal silicon rods. Therefore, the quality of single crystal silicon rods will eventually affect the quality of silicon wafers. In practical applications, the Czochralski (CZ) method is currently the main method for pulling single crystal silicon rods.

In the related art, the raw material used in the CZ method is polycrystalline granular silicon. However, due to the limitations of the production process, the hydrogen content of granular silicon is relatively high. In the feeding stage of growing silicon crystals by the Cz method, when the granular silicon comes into contact with the molten silicon, the hydrogen on the surface is released and forms hydrogen gas, causing the granular silicon to jump from the liquid surface and scatter to the outside of the crucible, while stirring up the silicon liquid to splash onto the thermal field components. At the same time, when the granular silicon melts, the large amount of hydrogen released also causes the liquid surface to jump, stirring up the silicon liquid to splash onto the thermal field components. If the silicon liquid splashed onto the thermal field components is not solidified in time and flows back into the silicon liquid, it will cause contamination of the thermal field components. Moreover, polishing the silicon points splashed on the thermal field components will also reduce the life of the thermal field components. In other words, the problem of granular silicon hydrogen jumping limits the large-scale application of granular silicon.

Summary of the invention

The present application aims to provide a silicon material melting method, a single crystal silicon rod pulling method and a single crystal silicon rod pulling device, so as to solve the problem of granular silicon hydrogen jumping in the existing single crystal silicon rod pulling process.

In order to solve the above technical problems, this application is implemented as follows:

In a first aspect, the present application discloses a silicon material melting method, the silicon material melting method comprising:

Providing a furnace body, wherein a crucible and a heater are housed in the furnace body;

Loading silicon material into the crucible;

adjusting the furnace pressure in the furnace body to a first preset range at a first preset rate;

adjusting the power of the heater to a second preset range at a second preset rate to heat the silicon material in the crucible;

The first preset time is maintained until the silicon material is melted into silicon liquid.

Optionally, in the step of adjusting the power of the heater to a second preset range at a second preset rate to heat the silicon material in the crucible, the rotation speed of the crucible satisfies a third preset range;

In the step of maintaining the first preset time length until the silicon material is melted into silicon liquid, the rotation speed of the crucible is gradually reduced.

Optionally, the step of gradually reducing the rotation speed of the crucible comprises:

The rotation speed of the crucible is gradually reduced until the rotation speed of the crucible is reduced to 0.

Optionally, before the step of adjusting the furnace pressure in the furnace body to a first preset range at a first preset rate, the step further includes:

Inert gas is introduced into the furnace body at a preset flow rate.

Optionally, the preset flow rate is 100-200 standard liters per minute.

Optionally, the first preset rate is 1-5 Torr per minute; the first preset range is 20, 20-35, 35, 35-75, 75, 75-80, 80, 50-100 Torr.

Optionally, the second preset rate is 10-30 kilowatts per hour, the second preset range is less than 120 kilowatts, and the third preset range is 5-10 revolutions per minute.

Optionally, the first preset duration is 5-30 minutes.

Optionally, the silicon material melting method further comprises:

The power of the heater is increased at a second preset rate and lasts for a second preset time, wherein the rotation speed of the crucible satisfies a fourth preset range.

Optionally, the second preset rate is 1 kilowatt per minute, the second preset time is 1 hour, and the fourth preset range is 5-10 revolutions per minute. A method for pulling a single crystal silicon rod, the method comprising:

Providing a furnace body and a feeder, wherein the furnace body is equipped with a crucible and a heater;

Using the feeder to load silicon material into the crucible;

adjusting the power of the heater to a second preset range at a second preset rate to heat the silicon material in the crucible, wherein the rotation speed of the crucible satisfies a third preset range;

The crucible speed is reduced to 0 and maintained for a first preset time until the silicon material is melted into silicon liquid;

Switching to the crystal pulling process, crystals are pulled from the silicon liquid in the crucible to obtain single crystal silicon rods.

In a second aspect, the present application further discloses a method for pulling a single crystal silicon rod. After the silicon material is melted by any of the above-mentioned silicon material melting methods, the single crystal silicon rod pulling method further includes:

Switch to the crystal pulling process to pull crystals from the silicon liquid in the crucible to obtain single crystal silicon rods.

Optionally, in the crystal pulling process, the power of the heater is 50-70 kilowatts, the furnace pressure in the furnace body is 5-20 torr, and the rotation speed of the crucible is 5-10 revolutions per minute.

In a third aspect, the present application further discloses a single crystal silicon rod pulling device, the single crystal silicon rod pulling device comprising:

Furnace body;

A crucible, which is disposed in the furnace body and is used to contain silicon material;

A heater, the heater is disposed in the furnace body and is used to heat the silicon material in the crucible;

Among them, after the silicon material is loaded into the crucible, the furnace pressure in the furnace body can be adjusted to a first preset range at a first preset rate; the power of the heater can be adjusted to a second preset range at a second preset rate to heat the silicon material in the crucible; the first preset time is maintained until the silicon material is melted into silicon liquid; and the crystal pulling process is switched to pull crystals from the silicon liquid in the crucible to obtain single crystal silicon rods.

In the embodiment of the present application, by adjusting the furnace pressure in the furnace body to a first preset range at a first preset rate, the hydrogen bond breaking rate in the silicon material and the release rate of hydrogen from the silicon liquid to the silicon liquid surface can be suppressed. By adjusting the power of the heater to a second preset range at a second preset rate to heat the silicon material in the crucible, the hydrogen bond breaking rate in the silicon material can be suppressed, and the melt convection in the silicon liquid can be reduced, thereby increasing the saturation of hydrogen in the silicon liquid and avoiding Prevent the hydrogen liquid in the silicon liquid from gathering into gas masses; by maintaining the first preset time length until the silicon material is melted into silicon liquid, the melt convection in the silicon liquid is reduced, the saturation of hydrogen in the silicon liquid is increased, and the hydrogen liquid in the silicon liquid is prevented from gathering into gas masses. In this way, it is possible to avoid the silicon liquid being splashed onto the thermal field components above the crucible and contaminating the thermal field components when hydrogen overflows during the melting of the silicon material into silicon liquid, thereby avoiding the operation of polishing the silicon points splashed on the thermal field components and increasing the service life of the thermal field components. In the embodiment of the present application, by suppressing the phenomenon of hydrogen jumping, it is conducive to the large-scale application of granular materials and reducing the raw material cost and production cost of single crystal silicon rods.

Additional aspects and advantages of the present application will be given in part in the description below, and in part will become apparent from the description below, or will be learned through the practice of the present application.

BRIEF DESCRIPTION OF THE DRAWINGS

In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the following is a brief introduction to the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

FIG1 is a flow chart of the steps of a method for melting silicon material according to an embodiment of the present application;

FIG2 is a schematic structural diagram of a single crystal silicon rod pulling device according to an embodiment of the present application;

FIG3 is a flow chart of another method for melting silicon material according to an embodiment of the present application;

Reference numerals: 10 - furnace body, 11 - crucible, 12 - heater, 13 - thermal field component, 20 - silicon material.

Specific embodiments

In order to make the purpose, technical solution and advantages of the embodiments of the present application clearer, the technical solution in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

The terms "first" and "second" in the specification and claims of this application may explicitly or implicitly include one or more of the features. In the description of this application, unless otherwise specified, "plurality" means two or more. In addition, the terms "and" in the specification and claims may include one or more of the features. /or" indicates at least one of the connected objects. The character "/" generally indicates that the related objects are in an "or" relationship.

In the description of the present application, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise", "axial", "radial", "circumferential" and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present application.

In the description of this application, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in this application can be understood according to specific circumstances.

Referring to Figure 1, a flow chart of the steps of a silicon material melting method described in an embodiment of the present application is shown. As shown in Figure 1, the silicon material melting method may specifically include the following steps:

Step 101: providing a furnace body, wherein a crucible and a heater are installed in the furnace body.

In the embodiment of the present application, a single crystal silicon rod pulling device (single crystal furnace) can be used to melt the silicon material to melt the silicon material into silicon liquid.

Referring to Figure 2, there is shown a structural schematic diagram of a single crystal silicon rod pulling device described in an embodiment of the present application. As shown in Figure 2, the single crystal silicon rod pulling device may specifically include: a furnace body 10; a crucible 11, the crucible 11 is arranged in the furnace body 10, and is used to accommodate silicon material 20; a heater 12, the heater 12 is arranged in the furnace body 10, and is used to heat the silicon material 20 in the crucible 11.

In practical applications, the furnace body 10 can be used as the main structure of the single crystal silicon rod pulling device, and is used to accommodate and support the crucible 11, the heater 12, and the heat shield and other thermal field components 13. The crucible 11 can be used to accommodate the silicon material 20, and the heater 12 can be arranged at the bottom and/or side of the crucible 11 to heat the crucible. The silicon material 20 in the crucible 11 is heated into silicon liquid and the silicon liquid is kept at a suitable temperature. A thermal field component 13 such as a heat shield can also be arranged above the crucible 11, and the thermal field component 13 can maintain a suitable thermal field environment in the furnace body 10 to facilitate the pulling of single crystal silicon rods.

Specifically, the single crystal silicon rod pulling device may further include a feeder (not shown in the figure), which extends from outside the furnace body 10 into the furnace body 10 and is used to add silicon material 20 into the crucible 11 .

Step 102: Load silicon material into the crucible.

In the embodiment of the present application, after the single crystal silicon rod pulling device is put into furnace, a feeder can be used to add silicon material 20 into the crucible 11. Specifically, the silicon material 20 can be granular silicon.

In a specific application, the silicon material 20 can also be added into the crucible 11 before the single crystal silicon rod pulling device and the furnace to avoid using a feeder. The embodiment of the present application does not specifically limit the feeding method of the silicon material 20.

Step 103: adjusting the furnace pressure in the furnace body to a first preset range at a first preset rate.

In the embodiment of the present application, an inert gas is introduced into the furnace body 10 to adjust the furnace pressure in the furnace body 10, so that the furnace pressure in the furnace body 10 is adjusted to a first preset range at a first preset speed, so as to increase the furnace pressure and reduce the partial pressure of hydrogen in the furnace atmosphere, inhibit the hydrogen bond breaking speed in the silicon material 20 and the release speed of hydrogen from the silicon liquid to the silicon liquid surface, and reduce the hydrogen escape rate to avoid the silicon liquid splashing onto the heat field component 13 above the crucible 11 when hydrogen overflows, thereby contaminating the heat field component 13 and improving the service life of the heat field component 13. In the embodiment of the present application, by inhibiting the phenomenon of hydrogen jumping, it is conducive to the large-scale application of granular materials and reducing the raw material cost and production cost of single crystal silicon rods.

In specific applications, when the furnace pressure rising rate in the furnace body 10 is too fast, it is easy to cause the return gas in the furnace to contaminate the silicon liquid and affect the crystal pulling. When the furnace pressure rising rate in the furnace body 10 is too slow, it will increase the invalid working hours and affect the production efficiency. In the embodiment of the present application, by adjusting the furnace pressure to the first preset range at a suitable first preset rate, it is possible to avoid the return gas in the furnace from contaminating the silicon liquid and affecting the crystal pulling, and to maintain a high production efficiency. By increasing the furnace pressure to the first preset range, the furnace pressure can be increased to reduce the partial pressure of hydrogen in the furnace atmosphere, reduce the hydrogen escape rate, and then achieve the purpose of suppressing hydrogen jump, which is conducive to the large-scale application of granular materials and reduces the raw material cost and production cost of single crystal silicon rods.

Optionally, the first preset rate can be 1-5 Torr per minute (Torr/min), and the first preset range is 20, 20-35, 35, 35-75, 75, 75-80, 80, 50-100 Torr. Relative to the furnace pressure level in the prior art, the technical solution adopted in the embodiment of the present application increases the furnace pressure and reduces the escape rate of hydrogen, thereby achieving the purpose of suppressing hydrogen jump. In practical applications, if the furnace pressure is too high, the silicon oxide volatiles cannot be carried away by the atmosphere in time, and adhere to components such as crystal rods and heat exchangers. After the particles fall off and fall into the molten silicon, they cannot be melted in time, which may cause wire breakage; if the furnace pressure is too low, it is not conducive to the escape of hydrogen, which will aggravate the phenomenon of hydrogen jump.

In practical applications, those skilled in the art can set specific values of the first preset rate and the first preset range according to actual needs. For example, the first preset rate can be 1, 1.5, 4 or 5 Torr per minute, and the value in the first preset range can be 50, 60, 78 or 100 Torr, etc. The embodiment of the present application does not limit the specific values of the first preset rate and the first preset range.

Step 104: Adjust the power of the heater to a second preset range at a second preset rate to heat the silicon material in the crucible.

In the embodiment of the present application, after the furnace pressure in the furnace body 10 is adjusted to the first preset range at the first preset rate, the heater 12 can be turned on, and the power of the heater 12 can be adjusted to the second preset range at the second preset rate to heat the silicon material 20 in the crucible 11. Optionally, during the power adjustment of the heater 12, the rotation speed of the crucible 11 can be adjusted to the third preset range to uniformly heat the silicon material 20 in the crucible 11.

Specifically, during the power adjustment of the heater 12 , the power of the heater 12 may be reduced first to suppress the hydrogen jump phenomenon, and then the power of the heater 20 may be increased after the silicon material 20 melts to a certain degree.

In a specific application, by adjusting the power of the heater 12 to a second preset range at a second preset rate to heat the silicon material 20 in the crucible 11, not only can the breaking speed of hydrogen bonds in the silicon material 20 be suppressed, but also the melt convection in the silicon liquid can be reduced, the saturation of hydrogen in the silicon liquid can be increased, and the hydrogen liquid in the silicon liquid can be prevented from gathering into gas masses. Thus, when hydrogen overflows, the silicon liquid can be prevented from splashing onto the thermal field component 13 above the crucible 11, causing contamination to the thermal field component 13, and the thermal field component 13 can be prevented from splashing onto the thermal field component 13 when polishing. The operation of the silicon point is improved, and the service life of the thermal field component 13 is increased. In the embodiment of the present application, by suppressing the phenomenon of hydrogen jump, it is beneficial to the large-scale application of granular materials and reduces the raw material cost and production cost of single crystal silicon rods.

In practical applications, when the power adjustment rate of the heater 12 is too fast, it is easy to cause a sharp change in the temperature of the molten silicon, which may easily cause internal crystallization and thus bring the risk of silicon leakage. When the power adjustment rate of the heater 12 is too slow, it will increase the ineffective working hours and affect the production efficiency. In the embodiment of the present application, by adjusting the power of the heater 12 to the second preset range at a suitable second preset rate, it is possible to avoid the sharp change in the temperature of the molten silicon, which may easily cause internal crystallization and thus bring the risk of silicon leakage, and maintain a high production efficiency. Moreover, it is also possible to suppress the breaking rate of hydrogen bonds in the silicon material 20, reduce the melt convection in the silicon liquid, increase the saturation of hydrogen in the silicon liquid, avoid the hydrogen liquid in the silicon liquid from gathering into gas masses, and suppress the phenomenon of hydrogen jumping, which is conducive to the large-scale application of granular materials and reduces the raw material cost and production cost of single crystal silicon rods.

Optionally, the second preset rate can be 10-30 kilowatts per hour (kw/h), the second preset range is less than 120 kilowatts (kw), and the third preset range is 5-10 revolutions per minute. Relative to the power of the heater 12 in the prior art (the power of the existing horizontal heater is 50-70 kilowatts), the technical solution adopted in the embodiment of the present application adjusts the power of the heater 12, reduces the escape rate of hydrogen, and thus achieves the purpose of suppressing hydrogen jump. During the power adjustment process of the heater 12, the crucible 11 can be coordinated with a certain rotation speed to achieve uniform heating of the silicon material 20 in the crucible 11.

In practical applications, those skilled in the art can set specific values of the second preset rate, the second preset range, and the third preset range according to actual needs. For example, the second preset rate can be 10, 12, 20, or 30 kilowatts per hour, etc. The values in the second preset range can be 70, 90, 103, 120 kilowatts, etc. The values in the third preset range can be 5, 6, 9, 10 revolutions per minute, etc. The embodiment of the present application does not limit the specific values of the second preset rate, the second preset range, and the third preset range.

Step 105: Maintaining the first preset time length until the silicon material is melted into silicon liquid.

In the embodiment of the present application, after the power of the heater 12 is increased to the second preset range, The first preset time period may be maintained until the silicon material is fully melted into silicon liquid.

Optionally, the first preset time is 5-30 minutes. In a specific application, after the power of the heater 12 meets the second preset range and the crucible 11 stops rotating, it is maintained for 5-30 minutes, which is conducive to fully melting the silicon material 20 in the crucible 11 into silicon liquid.

It should be noted that, in a specific application, those skilled in the art may set a specific value of the first preset time length according to the material of the silicon material 20, the quality of the silicon material 20, etc. For example, the first preset time length may be 5, 10, 18, 22 or 30 minutes, etc., and the embodiment of the present application may not limit the specific value of the first preset time length.

Optionally, after the power of the heater 12 is increased to the second preset range, the rotation speed of the crucible 11 can also be gradually reduced to reduce the melt convection in the silicon liquid, increase the saturation of hydrogen in the silicon liquid, and avoid the hydrogen liquid in the silicon liquid from gathering into gas masses. In this way, it is possible to avoid the overflow of hydrogen in the process of melting the silicon material 20 into silicon liquid, which may cause the silicon liquid to splash onto the thermal field component 13 above the crucible 11 and contaminate the thermal field component 13, thereby avoiding the operation of polishing the silicon points splashed on the thermal field component 13 and improving the service life of the thermal field component 13. In the embodiment of the present application, by suppressing the phenomenon of hydrogen jumping, it is conducive to the large-scale application of granular materials and reduces the raw material cost and production cost of single crystal silicon rods.

Optionally, gradually reducing the rotation speed of the crucible 11 may include: gradually reducing the rotation speed of the crucible until the rotation speed of the crucible is reduced to 0, that is, controlling the crucible 11 to stop rotating, so as to reduce melt convection in the silicon liquid, increase the saturation of hydrogen in the silicon liquid, and prevent the hydrogen liquid in the silicon liquid from gathering into gas masses.

In summary, the silicon material melting method described in the embodiment of the present application can at least include the following advantages:

In the embodiment of the present application, by adjusting the furnace pressure in the furnace body to a first preset range at a first preset rate, the breaking rate of hydrogen bonds in the silicon material and the release rate of hydrogen moving from the inside of the silicon liquid to the surface of the silicon liquid can be suppressed. By adjusting the power of the heater to a second preset range at a second preset rate to heat the silicon material in the crucible, the breaking rate of hydrogen bonds in the silicon material can be suppressed, and the melt convection in the silicon liquid can be reduced, the saturation of hydrogen in the silicon liquid can be increased, and the hydrogen liquid in the silicon liquid can be prevented from gathering into gas masses; by maintaining the first preset time until the silicon material melts into silicon liquid, the melt convection in the silicon liquid can be reduced, the saturation of hydrogen in the silicon liquid can be increased, and the hydrogen liquid in the silicon liquid can be prevented from gathering into gas masses. The hydrogen liquid in the silicon liquid gathers into gas masses. In this way, it is possible to avoid the silicon liquid being splashed onto the thermal field components above the crucible and contaminating the thermal field components when hydrogen overflows during the melting of the silicon material into silicon liquid, thereby avoiding the operation of polishing the silicon points splashed on the thermal field components and improving the service life of the thermal field components. In the embodiment of the present application, by suppressing the phenomenon of hydrogen jumping, it is beneficial to the large-scale application of granular materials and reducing the raw material cost and production cost of single crystal silicon rods.

3 , a flow chart of another method for melting silicon material according to an embodiment of the present application is shown. As shown in FIG3 , the method for melting silicon material may specifically include the following steps:

Step 301: providing a furnace body, wherein a crucible and a heater are installed in the furnace body.

In the embodiment of the present application, the specific operation process of step 301 can refer to step 101 in the aforementioned embodiment and will not be repeated here.

Step 302: Load silicon material into the crucible.

In the embodiment of the present application, the specific operation process of step 302 can refer to step 102 in the aforementioned embodiment and will not be repeated here.

Step 303: Introduce inert gas into the furnace body at a preset flow rate.

In the embodiment of the present application, after the silicon material is loaded into the crucible, an inert gas can be introduced into the furnace body 10 at a preset flow rate to quickly take away the hydrogen in the furnace body 10, further avoiding the hydrogen jump phenomenon, which is beneficial to the large-scale application of granular materials and reducing the raw material cost and production cost of single crystal silicon rods.

Optionally, the preset flow rate is 100-200 standard liters per minute (slpm). Compared with the multi-gas flow rate in the prior art (the current level of inert gas flow rate is 50-100slpm), the technical solution adopted in the embodiment of the present application increases the inert gas flow rate, quickly takes away the hydrogen in the furnace body, and thus achieves the purpose of suppressing hydrogen jump.

In practical applications, those skilled in the art can set the specific value of the preset flow rate according to actual needs. For example, the preset flow rate can be 100, 120, 150, 190 or 200 standard liters per minute, etc. The present application embodiment does not limit the specific value of the preset flow rate.

Step 304: adjusting the furnace pressure in the furnace body to a first preset range at a first preset rate.

In the embodiment of the present application, the specific operation process of step 304 can refer to step 103 in the aforementioned embodiment and will not be described in detail here.

Step 305: adjusting the power of the heater to a second preset range at a second preset rate to heat the silicon material in the crucible, wherein the rotation speed of the crucible satisfies a third preset range.

In the embodiment of the present application, the specific operation process of step 305 can refer to step 104 in the aforementioned embodiment and will not be repeated here.

Step 306: gradually reducing the rotation speed of the crucible and maintaining it for a first preset time period until the silicon material is melted into silicon liquid.

In the embodiment of the present application, the specific operation process of step 306 can refer to step 105 in the aforementioned embodiment and will not be repeated here.

Step 307: increasing the power of the heater at a second preset rate and continuing for a second preset time, wherein the rotation speed of the crucible satisfies a fourth preset range.

In the embodiment of the present application, after the silicon material in the crucible 11 is fully melted into silicon liquid, the power of the heater 12 can be increased at a second preset rate and continued for a second preset time, wherein the rotation speed of the crucible 11 satisfies the fourth preset range, so that the hydrogen in the silicon liquid can slowly overflow. In this way, the hydrogen in the silicon liquid can be slowly released to avoid the agglomeration of hydrogen in the silicon liquid affecting the subsequent crystal pulling process, thereby improving the quality of the single crystal silicon rod. The hydrogen jump phenomenon formed when hydrogen overflows quickly can also be avoided, which is conducive to the large-scale application of granular materials and reduces the raw material cost and production cost of single crystal silicon rods.

In this step, the crucible 11 can rotate at a certain speed to make the melt in the silicon liquid convect, reduce the saturation of hydrogen in the silicon liquid, and make the hydrogen in the silicon liquid slowly gather into gas masses and overflow. That is, the purpose of controlling the overflow speed of the hydrogen is achieved by rotating the crucible 11 in conjunction with the power of the heater 12.

Optionally, the second preset rate is 1 kilowatt per minute, the second preset time is 1 hour, and the fourth preset range is 5-10 revolutions per minute, so that the hydrogen in the silicon liquid can be released slowly at a certain rate to avoid hydrogen jump phenomenon.

It should be noted that, in a specific application, those skilled in the art can set the second preset rate, the second preset time and the specific values of the fourth preset range according to the material of the silicon material 20, the quality of the silicon material 20 and the like. For example, the second preset rate can be 0.5, 0.8 or 1. kilowatts per minute, etc. The second preset time length may be 0.5, 0.6, 0.8 or 1 hour, etc., and the value of the fourth range may be 5, 6, 9, 10 revolutions per minute, etc. The embodiment of the present application does not limit the specific values of the second preset rate, the second preset time and the fourth preset range.

In the embodiment of the present application, during the melting process of the silicon material, by suppressing the breaking speed of hydrogen bonds in the silicon material, reducing the melt convection in the silicon liquid, increasing the saturation of hydrogen in the silicon liquid, and avoiding the hydrogen liquid in the silicon liquid from gathering into gas masses; and reducing the melt convection in the silicon liquid, increasing the saturation of hydrogen in the silicon liquid, and avoiding the hydrogen liquid in the silicon liquid from gathering into gas masses. In this way, it is possible to avoid the silicon liquid from being splashed onto the thermal field parts above the crucible when hydrogen overflows during the melting of the silicon material into silicon liquid, thereby avoiding the operation of polishing the silicon points splashed on the thermal field parts, and improving the service life of the thermal field parts. Moreover, after the silicon material in the crucible is fully melted into silicon liquid, the power of the heater can be increased at a second preset rate and continued for a second preset time, so that the hydrogen in the silicon liquid can slowly overflow. In this way, the hydrogen in the silicon liquid can be slowly released, avoiding the agglomeration of hydrogen in the silicon liquid to affect the subsequent crystal pulling process, and improving the quality of the single crystal silicon rod. It can also avoid the hydrogen jump phenomenon caused by rapid hydrogen overflow, which is conducive to the large-scale application of granular materials and reduces the raw material cost and production cost of single crystal silicon rods.

An embodiment of the present application also provides a method for pulling a single crystal silicon rod. After melting the silicon material using the above-mentioned silicon material melting method, the method for pulling a single crystal silicon rod may further include: switching to a crystal pulling process, pulling crystals from the silicon liquid in the crucible to obtain a single crystal silicon rod.

In the embodiment of the present application, after the silicon material 20 in the crucible 11 is fully melted into silicon liquid, it is possible to switch to the crystal pulling process, that is, performing seeding, shouldering, and equal diameter operations in the silicon liquid, and pulling crystals from the silicon liquid in the crucible 11 to obtain single crystal silicon rods.

Specifically, the seeding operation can be: inserting the seed crystal into the silicon liquid to draw out a thin neck of a certain length and a diameter of 3 to 5 mm to eliminate crystal dislocations. The shoulder release operation can be: enlarging the diameter of the thin neck to the target diameter. When the thin neck grows to a sufficient length and reaches a certain pulling rate, the pulling speed can be reduced to release the shoulder. The equal diameter operation can be specifically: when the crystal is basically achieved When the diameter grows uniformly and reaches the target diameter, it can be pulled into a single crystal silicon rod.

In some optional embodiments of the present application, before performing the crystal pulling operation, the furnace pressure of the furnace body 10, the rotation speed of the crucible 11, and the power of the heater 12 can be changed to provide a more suitable crystal pulling environment. Specifically, the power of the heater 12 can be adjusted to 50-70 kilowatts, the furnace pressure in the furnace body 10 can be adjusted to 5-20 Torr, and the rotation speed of the crucible 11 can be adjusted to 5-10 revolutions per minute.

In the prior art, due to the existence of hydrogen jumping phenomenon, silicon liquid is easy to splash onto the thermal field component 13 to form silicon dots during the hydrogen release process. As time goes by, the silicon dots attached to the thermal field component 13 are easy to fall off from the thermal field component 13, resulting in the breakage of the single crystal silicon rod, which greatly reduces the quality and production efficiency of the single crystal silicon rod.

In the embodiment of the present application, since the phenomenon of hydrogen jumping is avoided, the phenomenon of silicon points on the thermal field component 13 falling off can be avoided during the operations of seeding, shouldering, equal diameter, etc., which greatly reduces the breakage of the single crystal silicon rod and improves the quality and production efficiency of the single crystal silicon rod.

In practical applications, since the addition of granular silicon is likely to cause the phenomenon of hydrogen jumping, the addition of granular material is likely to increase the disconnection rate of the single crystal silicon rod accordingly. Since the technical solution described in the embodiment of the present application can avoid the phenomenon of hydrogen jumping and reduce the disconnection rate of the single crystal silicon rod, it is conducive to the widespread application of granular silicon, and is conducive to the use of the CZ method to draw single crystal silicon rods, reducing the production cost of the single crystal silicon rods and improving the quality of the single crystal silicon rods. The following table shows the disconnection rate of silicon materials in different comparative test groups when single crystal silicon rods are drawn using the CZ method.

As shown in the table above, the experimental groups for pulling single crystal silicon rods using the existing process are Comparative Group 1, Comparative Group 2, and Comparative Group 3. Among them, the silicon material of Comparative Group 1 is native polycrystalline silicon without adding granular silicon, the proportion of granular silicon to native polycrystalline in the silicon material of Comparative Group 2 is 20%, and the silicon material of Comparative Group 3 is all granular silicon. The experimental groups for pulling single crystal silicon rods using the process of the present application are Example 1, Example 2, and Example 3. Embodiment 3 and Embodiment 4. Among them, in the silicon material of Embodiment 1, the proportion of granular silicon to native polycrystalline is 20%; in the silicon material of Embodiment 2, the proportion of granular silicon to native polycrystalline is 40%; in the silicon material of Embodiment 3, the proportion of granular silicon to native polycrystalline is 80%; and the silicon material of Embodiment 4 is all granular silicon.

As shown in the table above, when the existing process is used to pull single crystal silicon rods, the average single wire breakage rate of comparison group 2 (49.09%) and the average single wire breakage rate of comparison group 3 (62.24%) are both greater than the average single wire breakage rate of comparison group 1 (35.66%). It can be seen that the addition of granular silicon will increase the wire breakage rate of single crystal silicon rods, and as the proportion of granular silicon increases, the wire breakage rate of single crystal silicon rods will further increase. When the process of the present application is used to pull single crystal silicon rods, the average single wire breakage rate of Example 1 (36.11%), the average single wire breakage rate of Example 2 (35.38%), the average single wire breakage rate of Example 3 (35.32%), and the average single wire breakage rate of Example 4 (36.67%) are basically the same as the average single wire breakage rate of comparison group 1 (35.66%). It can be seen that, by using the crystal pulling process described in the embodiment of the present application, the addition of granular silicon does not increase the disconnection rate of the single crystal silicon rod, and as the proportion of granular silicon increases, the disconnection rate of the single crystal silicon rod can remain unchanged. That is, by suppressing the phenomenon of hydrogen jump, the embodiment of the present application is conducive to the large-scale application of granular materials and reduces the raw material cost and production cost of single crystal silicon rods.

In summary, the single crystal silicon rod pulling method described in the embodiment of the present application can at least include the following advantages:

In the embodiment of the present application, by adjusting the furnace pressure in the furnace body to the first preset range at a first preset rate; the hydrogen bond breaking speed in the silicon material and the release speed of hydrogen from the inside of the silicon liquid to the surface of the silicon liquid can be suppressed. By adjusting the power of the heater to the second preset range at a second preset rate to heat the silicon material in the crucible, the hydrogen bond breaking speed in the silicon material can be suppressed, and the melt convection in the silicon liquid can be reduced, the saturation of hydrogen in the silicon liquid can be increased, and the hydrogen liquid in the silicon liquid can be prevented from gathering into gas masses; by reducing the speed of the crucible to 0 and maintaining the first preset time until the silicon material is melted into silicon liquid, the melt convection in the silicon liquid is reduced, the saturation of hydrogen in the silicon liquid can be increased, and the hydrogen liquid in the silicon liquid can be prevented from gathering into gas masses. In this way, it is possible to avoid the silicon liquid being splashed onto the heat field component above the crucible when hydrogen overflows during the melting of the silicon material into silicon liquid, thereby avoiding the operation of polishing the silicon points splashed on the heat field component and improving the service life of the heat field component. In the embodiment of the present application, by suppressing the phenomenon of hydrogen jump, It is conducive to the large-scale application of granular materials and reduces the raw material cost and production cost of single crystal silicon rods.

The embodiment of the present application further provides a single crystal silicon rod pulling device as shown in FIG. 2 . As shown in FIG. 2 , the single crystal silicon rod pulling device may specifically include:

Furnace body 10;

A crucible 11, which is disposed in the furnace body 10 and is used to contain silicon material 20;

A heater 12, which is disposed in the furnace body 10 and is used to heat the silicon material 20 in the crucible 11;

A feeder, which extends from outside the furnace body 10 into the furnace body 10 and is used to add silicon material 20 into the crucible 11;

Among them, after the silicon material 20 is loaded into the crucible 11, the furnace pressure in the furnace body 10 can be adjusted to a first preset range at a first preset rate; the power of the heater 12 can be adjusted to a second preset range at a second preset rate to heat the silicon material 20 in the crucible 11, wherein the rotation speed of the crucible 11 satisfies a third preset range; the rotation speed of the crucible 11 is reduced to 0 and maintained for a first preset time until the silicon material 20 is melted into silicon liquid; switch to the crystal pulling process to pull crystals from the silicon liquid in the crucible 11 to obtain a single crystal silicon rod.

In a specific application, the furnace body 10 can be used as the main structure of the single crystal silicon rod pulling device, and is used to accommodate and support the crucible 11, the heater 12, and the thermal field components 13 such as the heat shield. The crucible 11 can be used to accommodate the silicon material 20, and the heater 12 can be arranged at the bottom and/or the side of the crucible 11 to heat the silicon material 20 in the crucible 11 into silicon liquid and keep the silicon liquid at a suitable temperature. A thermal field component 13 such as a heat shield can also be arranged above the crucible 11. The thermal field component 13 can maintain a suitable thermal field environment in the furnace body 10, which is conducive to the subsequent single crystal silicon rod pulling operation.

In the embodiment of the present application, by adjusting the furnace pressure in the furnace body to a first preset range at a first preset rate, the breaking rate of hydrogen bonds in the silicon material and the release rate of hydrogen from the inside of the silicon liquid to the surface of the silicon liquid can be suppressed. By adjusting the power of the heater to a second preset range at a second preset rate to heat the silicon material in the crucible, the breaking rate of hydrogen bonds in the silicon material can be suppressed, and the melt convection in the silicon liquid can be reduced, the saturation of hydrogen in the silicon liquid can be increased, and the hydrogen liquid in the silicon liquid can be prevented from gathering into gas masses; by reducing the rotation speed of the crucible to 0 and maintaining the first preset time until the silicon material melts into silicon liquid, the melt convection in the silicon liquid can be reduced, the saturation of hydrogen in the silicon liquid can be increased, and the hydrogen liquid in the silicon liquid can be prevented from gathering into gas masses. In this way, it can be This is to avoid the silicon liquid splashing onto the thermal field component above the crucible and contaminating the thermal field component when hydrogen overflows during the melting of the silicon material into silicon liquid, thereby avoiding the operation of polishing the silicon points splashed on the thermal field component and improving the service life of the thermal field component. In the embodiment of the present application, by suppressing the phenomenon of hydrogen jump, it is conducive to the large-scale application of granular materials and reducing the raw material cost and production cost of single crystal silicon rods.

The device embodiments described above are merely illustrative, wherein the units described as separate components may or may not be physically separated, and the components displayed as units may or may not be physical units, that is, they may be located in one place, or they may be distributed on multiple network units. Some or all of the modules may be selected according to actual needs to achieve the purpose of the scheme of this embodiment. Ordinary technicians in this field can understand and implement it without paying creative labor.

The term "one embodiment", "embodiment" or "one or more embodiments" herein means that a particular feature, structure or characteristic described in conjunction with the embodiment is included in at least one embodiment of the present application. In addition, please note that the examples of the term "in one embodiment" here do not necessarily all refer to the same embodiment.

In the description provided herein, a large number of specific details are described. However, it is understood that the embodiments of the present application can be practiced without these specific details. In some instances, well-known methods, structures and techniques are not shown in detail so as not to obscure the understanding of this description.

In the claims, any reference signs placed between brackets shall not be construed as limiting the claims. The word "comprising" does not exclude the presence of elements or steps not listed in the claims. The word "a" or "an" preceding an element does not exclude the presence of a plurality of such elements. The present application may be implemented by means of hardware comprising several different elements and by means of a suitably programmed computer. In a unit claim enumerating several means, several of these means may be embodied by the same item of hardware. The use of the words first, second, and third etc. does not indicate any order. These words may be interpreted as names.

Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the present application, rather than to limit it; although the present application is described in detail with reference to the above embodiments, ordinary technicians in the field Personnel should understand that they can still modify the technical solutions recorded in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of this application.

Claims

A silicon material melting method, characterized in that the silicon material melting method comprises:

Providing a furnace body, wherein a crucible and a heater are housed in the furnace body;

Loading silicon material into the crucible;

adjusting the furnace pressure in the furnace body to a first preset range at a first preset rate;

adjusting the power of the heater to a second preset range at a second preset rate to heat the silicon material in the crucible;

The first preset time is maintained until the silicon material is melted into silicon liquid.
The silicon material melting method according to claim 1, characterized in that in the step of adjusting the power of the heater to a second preset range at a second preset rate to heat the silicon material in the crucible, the rotation speed of the crucible satisfies a third preset range;

In the step of maintaining the first preset time length until the silicon material is melted into silicon liquid, the rotation speed of the crucible is gradually reduced.
The silicon material melting method according to claim 2, characterized in that the step of gradually reducing the rotation speed of the crucible comprises:

The rotation speed of the crucible is gradually reduced until the rotation speed of the crucible is reduced to 0.
The silicon material melting method according to claim 1, characterized in that before the step of adjusting the furnace pressure in the furnace body to a first preset range at a first preset rate, it also includes:

Inert gas is introduced into the furnace body at a preset flow rate.
The silicon material melting method according to claim 4, characterized in that the preset flow rate is 100-200 standard liters per minute.
The silicon material melting method according to claim 1 is characterized in that the first preset rate is 1-5 torr per minute; the first preset range is 20, 20-35, 35, 35-75, 75, 75-80, 80, 50-100 torr.
The silicon material melting method according to claim 2, characterized in that the second preset rate is 10-30 kilowatts per hour, and the second preset range is less than 120 kilowatts.
The silicon material melting method according to claim 2, characterized in that the first pre- Set the duration to 5-30 minutes.
The silicon material melting method according to any one of claims 1 to 8, characterized in that the silicon material melting method further comprises:

The power of the heater is increased at a second preset rate and lasts for a second preset time, wherein the rotation speed of the crucible satisfies a fourth preset range.
The silicon material melting method according to claim 9, characterized in that the second preset rate is 1 kilowatt per minute, the second preset time is 1 hour, and the fourth preset range is 5-10 revolutions per minute.
A method for pulling a single crystal silicon rod, characterized in that after melting the silicon material by the silicon material melting method according to any one of claims 1 to 10, the method for pulling a single crystal silicon rod further comprises:

Switch to the crystal pulling process to pull crystals from the silicon liquid in the crucible to obtain single crystal silicon rods.
The single crystal silicon rod pulling method according to claim 11 is characterized in that, in the crystal pulling process, the power of the heater is 50-70 kilowatts, the furnace pressure in the furnace body is 5-20 torr, and the rotation speed of the crucible is 5-10 revolutions per minute.
A single crystal silicon rod pulling device, characterized in that the single crystal silicon rod pulling device comprises:

Furnace body;

A crucible, which is disposed in the furnace body and is used to contain silicon material;

A heater, the heater is disposed in the furnace body and is used to heat the silicon material in the crucible;

Among them, after the silicon material is loaded into the crucible, the furnace pressure in the furnace body can be adjusted to a first preset range at a first preset rate; the power of the heater can be adjusted to a second preset range at a second preset rate to heat the silicon material in the crucible; the first preset time is maintained until the silicon material is melted into silicon liquid; and the crystal pulling process is switched to pull crystals from the silicon liquid in the crucible to obtain single crystal silicon rods.