Automatic crystal pulling method

Abstract

The invention relates to the technical field of semiconductors, in particular to an automatic crystal pulling method which comprises the steps of melting, charging, temperature adjusting and seeding, and the melting step comprises the step of collecting pixel information through a camera; the feeding step comprises the following steps: when the pixel information is lower than a threshold value, feeding raw materials into a crucible from a feeding hole in the side edge of the single crystal furnace by using a conveying device; welding is carried out in the temperature adjusting process, and whether welding is completed or not is judged according to the seed crystal aperture; the seeding step comprises the following steps: when the seeding length reaches the target length, judging whether the pulling speed of seeding meets the target pulling speed or not, and when the pulling speed of seeding does not meet the target pulling speed, correcting the heater power of the crucible according to a formula 1, the formula 1 is as follows: the correction power of the heater = (| actual seeding pulling speed-target seeding pulling speed |) * (0.01-0.03) + actual power of the heater during seeding; the method is high in automation degree, one-key crystal pulling can be achieved, and the survival rate of crystal bars can be effectively increased.

Description

Technical Field

[0001] The present invention relates to the field of semiconductor technology, and in particular to an automated crystal pulling method. Background Art

[0002] The Czochralski method is a commonly used production process for preparing single crystal silicon. Its main process steps include melting, welding, seeding, shoulder release, shoulder rotation, equal diameter, finishing, segmentation and feeding, and furnace shutdown.

[0003] However, the automation degree of the Czochralski method provided by the related art is different, and the survival rate of the produced crystal rod is low, usually difficult to exceed 70%. Summary of the invention

[0004] The object of the present invention is to provide an automated crystal pulling method, which has a high degree of automation and can achieve one-key crystal pulling, and can effectively improve the survival rate of the crystal rod, that is, the survival rate can significantly exceed 70%.

[0005] The present invention is achieved in that:

[0006] The present invention provides an automated crystal pulling method, comprising:

[0007] Melting the material, the step of melting the material includes collecting pixel information through a camera;

[0008] Adding materials, the step of adding materials includes using a conveying device to put the raw materials into the crucible from a feeding port on the side of the single crystal furnace when the pixel information is lower than a threshold value;

[0009] Temperature adjustment: welding is performed during the temperature adjustment process, and whether welding is completed is determined based on the seed crystal aperture;

[0010] Seeding, the step of seeding includes judging whether the seeding pulling speed meets the target pulling speed when the seeding length reaches the target length, and when the seeding pulling speed does not meet the target pulling speed, correcting the heater power of the crucible according to Formula 1, Formula 1 is: Correction power of heater = (|actual seeding pulling speed-target seeding pulling speed|) × (0.01~0.03) + actual power of heater during seeding.

[0011] In an optional embodiment, the temperature adjustment step includes: when the power of the heater is the set power, keeping warm for T1 time and then performing welding; wherein, T1 time = (|C0-C1|)×(10~15)-T0-(15~20)min, C0 is the initial temperature of the melt surface in the crucible when the heater starts to heat the crucible at the set power, T0 is the time the melt surface is maintained at the initial temperature; C1 is the target temperature of the melt surface when welding.

[0012] In an optional embodiment, the temperature adjustment step also includes: when the power of the heater is the set power, keeping warm for T2 time, T2 time = (C1-C2)×(10~15)-T1-(15~20min), wherein C2 is the target temperature of the melt surface when performing the crystal seeding step.

[0013] In an optional embodiment, the temperature adjustment step further includes adjusting the power of the heater to the target power of the crystal seeding step after time T2, and starting the crystal seeding step after time T3.

[0014] In an optional embodiment, the T3 time is 20 to 30 minutes.

[0015] In an optional embodiment, the automated crystal pulling method further includes: releasing the shoulder when the pulling speed of the seeded crystal meets the target pulling speed.

[0016] In an optional embodiment, the step of placing the shoulder includes controlling the rising speed of the crucible according to Formula 2 and Formula 3, controlling the power of the heater according to Formula 3 and Formula 4, and controlling the pulling speed of the crystal according to Formula 3 and Formula 5;

[0017] Formula 2: S 实际 =D 实际 2 / D 埚 2 ×2.33 / 2.53, Formula 3: D 实际 =L 实际 / tanQ; where S 实际 is the rising speed of the crucible, D 实际 is the actual diameter of the formed crystal rod, D 锅 is the inner diameter of the crucible; L 实际 is the height of the shoulder; Q is the angle of the bottom of the shoulder formed after the shoulder is released;

[0018] Formula 3: W 实际 =W 设定 -(∣D 实际 -D 设定 ∣)×set power factor; where W 实际 is the actual heating power of the heater, W 设定 is the set power of the heater, D 设定 is the target diameter of the crystal rod;

[0019] Formula 4: V 实际 =V 设定 +(D 实际 -D 设定 )×V 设定 ×Set the pulling speed coefficient; where V 实际 is the actual speed of crystal pulling, V 设定Set the speed for crystal pulling.

[0020] In an optional embodiment, the automated crystal pulling method further comprises: after the shoulder placement step, performing a shoulder rotation step and a diameter equalization step; wherein,

[0021] In the shoulder turning step, when the diameter of the formed crystal rod reaches the target diameter and has no tendency to increase, the step of equalizing the diameter is entered.

[0022] In an optional embodiment, the automated crystal pulling method further comprises: in the step of equalizing the diameter, using a CCD camera to detect the broken bud, and when the broken bud phenomenon is detected, executing the circulation step or the completion step; wherein,

[0023] The circulation section includes a tailing step, and the tailing step includes a secondary charging step: according to the amount of residual material in the crucible, the raw material to be supplemented is fed into the crucible from the feeding port on the side of the single crystal furnace by a conveying device, and in the secondary charging step, the previously formed crystal rod is lifted to the auxiliary chamber of the single crystal furnace for pressure maintenance;

[0024] The steps of the finishing section include: after the crystal breaks, when the amount of remaining material in the crucible is less than or equal to 50kg, stopping the furnace; or, after the crystal breaks, when the amount of remaining material in the crucible is greater than 150kg, taking the formed crystal rod out of the single crystal furnace and continuing to lead it; or, after the crystal breaks, when the amount of remaining material in the crucible is greater than 50kg and less than or equal to 150kg, continuing to perform the equal diameter step.

[0025] In an optional embodiment, a feeding mechanism is provided on the single crystal furnace, the feeding mechanism includes a material guide barrel and a vibration component, the material guide barrel is provided in the single crystal furnace and extends from the feed port into the single crystal furnace so that the discharge port of the material guide barrel is located above the crucible, and the vibration component is transmission-connected to the material guide barrel for driving the material guide barrel to vibrate; in the step of feeding, the raw material is delivered to the material guide barrel by a conveying device, and then the vibration component is used to drive the material guide barrel to shake the received raw material into the crucible; and / or,

[0026] Whether the welding is completed is judged according to the seed crystal aperture, specifically including: when the seed crystal aperture is slightly reduced by 1.2 to 1.5 mm, it is judged that the welding is completed.

[0027] The present invention has the following beneficial effects:

[0028] The automated crystal pulling method of the present invention determines whether to add raw materials through pixel information collected by a camera, and uses a conveying device to convey the raw materials to a feeding port on the side of a single crystal furnace so as to be fed into a crucible, thereby realizing automated feeding. In the crystal seeding step, the power of the heater is corrected according to Formula 1, thereby realizing an automated step of the power of the heater. In this way, the degree of automation of the entire crystal pulling process can be improved, which is conducive to achieving the purpose of one-click crystal pulling.

[0029] Moreover, during seeding, the heater power is corrected according to Formula 1, which can improve the stability of the seeding temperature and thus effectively improve the survival rate of the crystal rod. DETAILED DESCRIPTION

[0030] In order to make the purpose, technical scheme and advantages of the embodiments of the present invention clearer, the technical scheme in the embodiments of the present invention will be described clearly and completely below. If the specific conditions are not specified in the embodiments, they are carried out according to conventional conditions or conditions recommended by the manufacturer. If the manufacturer of the reagents or instruments used is not specified, they are all conventional products that can be purchased commercially.

[0031] The disclosed embodiments provide an automated crystal pulling method, which is a one-touch crystal pulling method, i.e., only the "start button" needs to be touched on the crystal pulling device to realize an automated crystal pulling process through the control system of the crystal pulling device; the structure and working principle of the above-mentioned crystal pulling device are similar to those of the related art, and similar contents will not be repeated here, and only the differences will be described in detail here.

[0032] It should be noted that before executing the automated crystal pulling method, it also includes the steps of dismantling and cleaning the furnace and hanging materials and closing the furnace; wherein, the steps of dismantling and cleaning the furnace include: cleaning the single crystal furnace that has been shut down, namely, cleaning the furnace cavity, cleaning the heat field, cleaning the pipeline, etc., and after the cleaning is completed, the heat field is loaded into the furnace in sequence; the step of hanging materials and closing the furnace includes placing the crucible containing native polycrystals in the single crystal furnace, specifically, hanging the quartz crucible containing native polycrystals into the carbon-carbon crucible, and then rotating the furnace cover of the single crystal furnace back.

[0033] It should also be noted that the methods of the above-mentioned cleaning processes are similar to related technologies and will not be repeated here.

[0034] The automated crystal pulling method of this embodiment includes: vacuuming, leak detection, pressurization, melting, initial feeding, continued melting, temperature adjustment, seeding, shoulder release, shoulder rotation, equal diameter, finishing or furnace shutdown, secondary feeding after finishing, re-melting, and repeating the steps of temperature adjustment, seeding, shoulder release, shoulder rotation, etc. starting from the temperature adjustment step until finishing or furnace shutdown again.

[0035] Optionally, the vacuuming step is similar to the related technology, for example: the control system of the crystal pulling equipment controls the main pump of the crystal pulling equipment to automatically start, and the vacuum is drawn to the pressure in the single crystal furnace ≤20mTorr, for example: 20mTorr, 18mTorr, 15mTorr, etc.

[0036] It should be noted that when the control system controls the main pump to start, the main pump can be started with a delay, for example, the main pump starts about 15 seconds after the control system sends the start command to the main pump.

[0037] Optionally, the leak detection step includes: after the vacuuming is completed, the control system automatically jumps to the leak detection step, wherein when the leak detection rate is less than 60mTorr·L / s, it is judged to meet the standard; if it meets the standard, the next process is entered, if it does not meet the standard, argon is flowed again to vacuumize and continue leak detection. The specific method of leak detection is similar to the related technology and will not be repeated here.

[0038] After the leak detection is completed, the control system automatically jumps to the pressurization step, and stabilizes the pressure inside the single crystal furnace by filling inert gases such as argon. The specific method is similar to the related technology and will not be repeated here.

[0039] Optionally, after the pressure treatment is completed, the control system is controlled to automatically jump to the step of melting the material to melt the material in the crucible.

[0040] It should be noted that the type and amount of the melt material can be obtained by looking up the melt formula table.

[0041] In the melting step, the camera can be used to collect pixel information, so that the melting degree of the material in the crucible can be detected, and whether to add material can be determined based on the melting condition of the material (for example: using the full melting method, the size of the molten silicon in the furnace is detected by pixel brightness, and the size of the molten silicon is compared with the molten silicon liquid to determine whether to add material, wherein the size of the molten silicon can refer to the amount or volume of non-melted polysilicon raw material).

[0042] Among them, the pixel information collected by the camera can be sent to the control system, and the control system determines whether to add materials based on the received pixel information, and when it is determined that adding materials is needed, the step of adding materials is performed, that is, the charging amount of the furnace of the crystal pulling system is a fixed value (that is, the furnace has an inherent charging amount, that is, the initial charging amount of the crucible in the step of hanging and closing the furnace is fixed), when the control system receives the pixel information collected and fed back by the camera, the control system compares the received pixel information with the threshold, and when it is determined that the pixel information is less than the threshold, the conveying device is controlled to put the raw materials that need to be added into the crucible from the feeding port on the side of the single crystal furnace. In this way, an automated charging process can be realized, which not only improves efficiency, but also ensures the consistency of crystal rods produced by crystal pulling.

[0043] It should be noted that the crystal pulling equipment includes a batching system, and the feeding device includes an AGV trolley; when the control system determines that feeding is required, the control system sends a feeding instruction to the batching system and the AGV trolley, and then the batching system provides the material to the AGV trolley, and the AGV trolley delivers the material to the single crystal furnace of the crystal pulling equipment, and enables the material to be put into the crucible from the feeding port on the side of the single crystal furnace. The above-mentioned batching system includes but is not limited to a batching machine with a weighing function.

[0044] Optionally, a feeding mechanism is provided on the single crystal furnace, and the feeding mechanism includes a material guide barrel and a vibration component. The material guide barrel is provided in the single crystal furnace and extends from the feed port into the single crystal furnace so that the discharge port of the material guide barrel is located above the crucible. The vibration component is in transmission connection with the material guide barrel and is used to drive the material guide barrel to vibrate. In the step of feeding, the raw material is delivered to the material guide barrel by a conveying device (i.e., an AGV trolley), and then the vibration component is used to drive the material guide barrel to vibrate, so that the received raw material is shaken into the crucible through the feed port under the guidance of the material guide barrel. The vibration component includes but is not limited to a vibration motor; the setting of the vibration component can improve the efficiency and reliability of feeding.

[0045] Furthermore, the feeding mechanism also includes a storage box (which can be understood as a hopper), which is connected to the end of the material guide barrel away from the single crystal furnace, and the storage box has a accommodating cavity. The transportation device (i.e., the AGV trolley) can unload the delivered material into the accommodating cavity of the storage box, and then under the vibration of the vibration component, the storage box vibrates together with the material guide barrel, so that the material in the accommodating cavity can fall into the crucible from the feed port under the guidance of the inner cavity of the guide barrel.

[0046] Optionally, the material guide barrel is arranged at an angle, and the end of the material guide barrel with a lower height extends from the feed port into the single crystal furnace, and the end of the material guide barrel with a lower height is arranged at the discharge port, and the material storage box is connected to the end of the material guide barrel away from the single crystal furnace (that is, the end of the material guide barrel with a higher height); in this way, it can be ensured that the raw materials in the accommodating cavity can fall into the crucible from the feed port more reliably and smoothly under the guidance of the material guide barrel.

[0047] Optionally, the material guide barrel is movably arranged in the single crystal furnace by plugging with the feed port of the single crystal furnace. In other embodiments, the material guide barrel can also be movably connected to the single crystal furnace by a guide rail assembly, and the guide rail assembly can guide the material guide barrel to move up and down, that is, when the vibration assembly drives the material guide barrel to vibrate, the material guide barrel can vibrate up and down under the guidance of the guide rail assembly.

[0048] After the addition of materials is completed and the added materials are melted, the control system controls the execution of the temperature adjustment step; wherein, welding is performed during the temperature adjustment process, and whether the welding is completed is determined based on the aperture of the seed crystal. Specifically, during the welding process, the aperture information of the seed crystal is photographed by a camera, and the aperture information of the seed crystal is sent to the control system, and the control system determines whether the welding is completed based on the received aperture information of the seed crystal.

[0049] Optionally, the control system determines whether the welding is completed according to the seed crystal aperture, specifically including: the control system determines that the welding is completed when the seed crystal aperture is slightly reduced by 1.2 to 1.5 mm according to the received seed crystal aperture information.

[0050] Optionally, the temperature adjustment step includes: when the power of the heater is the set power, the heat preservation time T1 is followed by welding; wherein T1 time = (|C0-C1|)×(10-15)-T0-(15-20) min, C0 is the initial temperature of the melt surface in the crucible when the heater starts to heat the crucible at the set power, T0 is the time the melt surface is maintained at the initial temperature; C1 is the target temperature of the melt surface during welding. In this way, the reliability of welding can be ensured to improve the crystallization rate.

[0051] It should also be noted that during welding, the temperature can be tested by fine crystals, and when the seed crystal is not melted, the seed crystal can be lowered for primary seed crystal welding to ensure the reliability of welding.

[0052] Optionally, the temperature adjustment step also includes: when the power of the heater is the set power, keeping warm for T2 time, T2 time = (C1-C2)×(10~15)-T1-(15~20min), wherein C2 is the target temperature of the melt surface when performing the crystal seeding step.

[0053] Optionally, the temperature adjustment step further includes adjusting the power of the heater to the target power of the seeding step after T2 time, and starting the seeding step after T3 time (i.e., stabilizing the temperature for T3 time with the power of the heater as the target power of the seeding). In this way, the stability of the seeding temperature can be ensured to improve the crystallization rate.

[0054] Optionally, the T3 time is 20 to 30 minutes, for example, 20 minutes, 22 minutes, 25 minutes, 27 minutes, 30 minutes, etc., which is not specifically limited here.

[0055] It should be noted that during the entire temperature adjustment process, the duration is controlled at 70 minutes to 90 minutes.

[0056] After temperature adjustment, the temperature of the melt surface is stable, and the step of seeding is automatically executed by the control system; wherein, the step of seeding includes judging whether the seeding pulling speed meets the target pulling speed when the seeding length reaches the target length, and when the seeding pulling speed does not meet the target pulling speed, correcting the heater power of the crucible according to Formula 1, Formula 1 is: Correction power of heater = (|actual seeding pulling speed-target seeding pulling speed|) × (0.01~0.03) + actual power of heater during seeding.

[0057] In the crystal seeding step, the heater power is corrected according to Formula 1, and the heater power automation step can be realized; thus, the automation level of the entire crystal pulling process can be improved, which is conducive to achieving the purpose of one-key crystal pulling. Moreover, in the crystal seeding, the heater power is corrected according to Formula 1, which can improve the stability of the crystal seeding temperature, thereby effectively improving the survival rate of the crystal rod.

[0058] Optionally, the target pulling speed is 260-320 mm / h, for example, 260 mm / h, 280 mm / h, 300 mm / h, 320 mm / h, etc., which is not specifically limited here.

[0059] Optionally, the target length of the seeding (ie, the length of the fine crystal) can be 150-250 mm, for example, 150 mm, 180 mm, 200 mm, 220 mm, 250 mm, etc.

[0060] Furthermore, the automated crystal pulling method disclosed in the present invention further includes: when the pulling speed of the seeded crystal meets the target pulling speed, directly entering the step of shouldering; and when the pulling speed of the seeded crystal does not meet the target pulling speed, after adjusting the heater power according to the above formula 1, entering the step of shouldering. The shoulder grows in the shape of a pyramid and has a fixed shoulder shape, that is, the angle at the bottom of the shoulder is a set value Q. In the process of shouldering, the speed of the crucible rising, the power of the heater and the crystal pulling speed are adjusted according to the fixed shoulder shape of the shoulder (specifically, the angle at the bottom of the shoulder is the set value Q).

[0061] Furthermore, the rising speed of the crucible can be controlled according to Formula 2 and Formula 3, the power of the heater can be controlled according to Formula 3 and Formula 4, and the pulling speed of the crystal can be controlled according to Formula 3 and Formula 5; Formula 2, Formula 3, Formula 4, and Formula 5 are respectively as follows:

[0062] Formula 2: S 实际 =D 实际 2 / D 埚 2 ×2.33 / 2.53, Formula 3: D 实际 =L 实际 / tanQ; where S 实际 is the rising speed of the crucible, D 实际 is the actual diameter of the formed crystal rod, D 锅 is the inner diameter of the crucible; L 实际 is the height of the shoulder; Q is the angle of the bottom of the shoulder formed after the shoulder is released;

[0063] Formula 3: W 实际 =W 设定 -(∣D 实际 -D 设定 ∣)×set power factor; where W实际 is the actual heating power of the heater, W 设定 is the set power of the heater, D 设定 is the target diameter of the crystal rod, and setting the power factor refers to the PID corresponding to the heater power;

[0064] Formula 4: V 实际 =V 设定 +(D 实际 -D 设定 )×V 设定 ×Set the pulling speed coefficient; where V 实际 is the actual speed of crystal pulling, V 设定 It is the set speed of crystal pulling. Setting the pulling speed coefficient refers to the PID corresponding to the pulling speed.

[0065] By adjusting the shoulder release pot lifting speed, crystal pulling speed and heater power in this way, on the one hand, automatic adjustment can be achieved, and on the other hand, the pot lifting height, pulling speed and power can be adjusted in real time and adaptively according to the current pot lifting height, pulling speed and crystal rod diameter, so as to improve the survival rate of the obtained crystal rod (the survival rate can be increased by about 5% to 8%).

[0066] Optionally, in the shoulder release step, the crucible rotation speed can be controlled to 3-4rpm (for example: 3rpm, 3.5rpm, 4rpm, etc.), the crystal rotation speed can be controlled to 6-8rpm (for example: 6rpm, 7rpm, 8rpm, etc.), the argon flow rate can be controlled to 80-100slpm (for example: 80slpm, 90slpm, 100slpm, etc.), and the furnace pressure can be controlled to be 5-7Torr (for example: 5Torr, 6Torr, 7Torr, etc.).

[0067] It should be noted that whether the seeding pulling speed meets the target pulling speed is determined by the control system after receiving the seeding pulling speed information. When it is determined that the seeding pulling speed meets the target pulling speed, the crystal pulling equipment is controlled to enter the shoulder release step. When it is determined that the pulling speed does not meet the target pulling speed, the heater is controlled to make corrections according to the correction power of Formula 1.

[0068] It should also be noted that the actual diameter of the crystal rod and the angle Q at the bottom of the shoulder formed after the shoulder is released can be obtained by detecting the corresponding image information through the optical measurement mechanism configured by the crystal pulling equipment, and sending the detected image information to the control system, which processes the received image information.

[0069] Of course, in other embodiments, the directness of the crystal rod and the angle Q at the bottom of the shoulder formed after shoulder release can also be obtained by detecting by a laser measurement mechanism, an X-ray detection mechanism, etc. configured in the crystal pulling equipment. The specific detection method is similar to the related technology and will not be repeated here.

[0070] After the growth diameter of the shoulder reaches the target diameter (for example: 250-302mm), under the control of the control system, it automatically enters the shoulder rotation step, and the growth direction of the crystal will be changed to make the crystal grow vertically downward; among them, when the control system determines that the diameter of the crystal rod has reached the set diameter (that is, the target diameter) and there is no increase trend, the control system controls the automatic entry into the equal diameter step.

[0071] It should be noted that, in the shoulder release step, a CCD camera can be used to take a picture of the crystal rod to extract pixel information of the crystal rod, and the extracted pixel information is sent to the control system, which compares the received pixel information (pixel value) with the target pixel information, and determines that the diameter of the crystal rod has reached the set diameter (i.e., the target diameter) when the received pixel information matches the target pixel information.

[0072] In the equal diameter step, a CCD camera is used to detect the broken bud. The CCD camera sends the image information of the crystal rod to the control system, and the control system determines whether the broken bud appears downward according to the image information, and executes the cycle section step or the completion section step when it is determined that the broken bud phenomenon occurs (that is, when the CCD detects the broken bud phenomenon). Among them, the cycle section refers to: after the preparation of the previous crystal rod is completed, the secondary feeding is carried out, and the material is melted after the secondary feeding, and the steps of temperature adjustment, crystal seeding, shoulder release, shoulder rotation, etc. are repeated from the temperature adjustment step until the furnace is stopped; the completion section refers to: after the preparation of the previous crystal rod is completed, the secondary feeding and other steps after the secondary feeding are no longer carried out.

[0073] In the equal diameter step, the crystal rod grows longitudinally with equal diameter. As the length of the crystal rod (crystal) increases, the amount of residual material in the crucible decreases. In the circulation section step, if the amount of residual material in the crucible reaches the target set amount, the closing step can be entered. The closing step includes secondary feeding: according to the amount of residual material in the crucible, the raw materials to be supplemented are fed into the crucible from the feeding port on the side of the single crystal furnace by a conveying device, and in the secondary feeding step, the previously formed crystal rod is lifted to the auxiliary chamber of the single crystal furnace for pressure maintenance, that is, after the previously formed crystal (crystal rod) is broken, under the control of the control system, The crystal rod will be taken out and isolated in the auxiliary chamber of the single crystal furnace for cooling and pressure maintenance. At this time, the remaining material amount in the crucible is calculated. When the remaining material amount reaches the target set amount (for example: the initial charge amount in the crucible is 800g, the remaining material amount in the crucible is 200g, the total amount of crystal rods formed by crystal pulling is 600g, and the remaining 200g in the crucible meets the target set amount), it is determined that the conditions for secondary feeding are met, and the control system will send a secondary feeding instruction to the batching system and the feeding device, so that the batching system and the feeding device add the material to the crucible in a similar manner to the initial feeding.

[0074] During the secondary feeding, there is no need to take out the previously formed crystal rod. Instead, the secondary feeding can be achieved from the feed port on the side of the single crystal furnace while the crystal rod is maintaining pressure in the auxiliary chamber, which can effectively improve the feeding efficiency and save work time.

[0075] It should be noted that the weight of the material in the crucible can be obtained by directly weighing the weighing component arranged at the bottom of the crucible, and the weighing component sends the information of the weighed remaining material amount to the control system, and the control system judges that the conditions for re-feeding are met based on the received remaining material amount and the target set amount when the received remaining material amount is greater than or equal to the target set amount.

[0076] It should also be noted that the target setting amount can be obtained based on experience, for example, it can also be 150g, 250g, etc., and is not specifically limited here.

[0077] The crystal rod that has completed cooling and pressure holding in the auxiliary chamber can be delivered by the AGV car to the machining workshop for cutting, slicing, and quality measurement. The measured quality data can be fed back to the control system, which compares the measured quality data with the quality data indicators stored in its database. If the measured quality data is compared with the quality data indicators in the database and meets the standards, the control system controls the normal flow of the crystal pulling equipment. If the measured quality data is compared with the quality data indicators in the database and does not meet the standards, the control system feeds back an alarm and controls the pulling speed equipment to stop, that is, an abnormal alarm and pulling stop processing are performed.

[0078] In the steps of the finishing section, the control system is also used to determine the amount of remaining material in the crucible, wherein after the crystal breaks, when the amount of remaining material in the crucible is less than or equal to 50kg, the furnace is stopped to allow the furnace to cool; or, after the crystal breaks, when the amount of remaining material in the crucible is greater than 150kg, the previously formed crystal rod is taken out of the single crystal furnace and continues to be introduced; or, after the crystal breaks, when the amount of remaining material in the crucible is greater than 50kg and less than or equal to 150kg, the equal diameter step is continued.

[0079] It should be noted that after stopping the furnace, the furnace can be restarted according to the amount of remaining material in the crucible. The specific furnace restart interval is similar to the related technology. It is only necessary to avoid problems such as furnace burnout caused by abnormal furnace. It should be understood that when the amount of remaining material in the crucible is large, the furnace restart time can be extended.

[0080] It should also be noted that all formulas involved in the present disclosure are stored in the control system and are called by the control system in the corresponding process steps.

[0081] In summary, the automated crystal pulling method of the present invention has a high degree of automation and can achieve one-click crystal pulling, which can effectively improve the survival rate of the crystal rod, that is, the survival rate can significantly exceed 70%.

[0082] The above are only preferred embodiments of the present invention and are not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. An automated crystal pulling method, characterized in that: include: Melting material, the melting step comprising collecting pixel information through a camera; Adding materials, the step of adding materials comprising, when the pixel information is lower than a threshold value, using a conveying device to put the raw materials into the crucible from a feeding port on the side of the single crystal furnace; Temperature adjustment, during which welding is performed, and whether welding is completed is determined according to the seed crystal aperture; Seeding, the step of seeding includes judging whether the pulling speed of the seeding meets the target pulling speed when the length of the seeding reaches the target length, and when the pulling speed of the seeding does not meet the target pulling speed, correcting the heater power of the crucible according to Formula 1, Formula 1 is: corrected power of the heater = (|actual seeding pulling speed-target seeding pulling speed|) × (0.01~0.03) + actual power of the heater during seeding.

2. The automated crystal pulling method according to claim 1, characterized in that: The temperature adjustment step includes: when the power of the heater is the set power, the welding is performed after the heat preservation time T1; wherein the T1 time = (|C0-C1|)×(10~15)-T0-(15~20)min, C0 is the initial temperature of the melt surface in the crucible when the heater starts to heat the crucible with the set power, T0 is the time the melt surface is maintained at the initial temperature; C1 is the target temperature of the melt surface when the welding is performed.

3. The automated crystal pulling method according to claim 2, characterized in that: The temperature adjustment step also includes: when the power of the heater is the set power, keeping warm for T2 time, the T2 time = (C1-C2)×(10~15)-T1-(15~20min), wherein C2 is the target temperature of the melt surface when performing the seeding step.

4. The automated crystal pulling method according to claim 3, characterized in that: The temperature adjustment step further includes adjusting the power of the heater to a target power of the seeding step after T2 time, and starting the seeding step after T3 time.

5. The automated crystal pulling method according to claim 4, characterized in that: The T3 time is 20 to 30 minutes.

6. The automated crystal pulling method according to claim 1, characterized in that: The automated crystal pulling method further includes: releasing the shoulder when the pulling speed of the seeded crystal meets the target pulling speed.

7. The automated crystal pulling method according to claim 6, characterized in that: The step of releasing the shoulders includes controlling the rising speed of the crucible according to Formula 2 and Formula 3, controlling the power of the heater according to Formula 3 and Formula 4, and controlling the pulling speed of the crystal according to Formula 3 and Formula 5; Formula 2: S 实际 =D 实际 2 / D 埚 2 ×2.33 / 2.53, Formula 3: D 实际 =L 实际 / tanQ; where S 实际 is the rising speed of the crucible, D 实际 is the actual diameter of the formed crystal rod, D 锅 is the inner diameter of the crucible; L 实际 is the height of the shoulder; Q is the angle of the bottom of the shoulder formed after the shoulder is released; Formula 3: W 实际 =W 设定 -(∣D 实际 -D 设定 ∣)×set power factor; where W 实际 is the actual heating power of the heater, W 设定 is the set power of the heater, D 设定 is the target diameter of the crystal rod; Formula 4: V 实际 =V 设定 +(D 实际 -D 设定 )×V 设定 ×Set the pulling speed coefficient; where V 实际 is the actual speed of crystal pulling, V 设定 Set the speed for crystal pulling.

8. The automated crystal pulling method according to claim 6, characterized in that: The automated crystal pulling method further comprises: after the shoulder release step, performing a shoulder rotation step and a diameter equalization step; wherein, In the shoulder turning step, when the diameter of the formed crystal rod reaches the target diameter and has no tendency to increase, the step of equalizing the diameter is entered.

9. The automated crystal pulling method according to claim 8, characterized in that: The automated crystal pulling method further comprises: in the step of equalizing the diameter, using a CCD camera to detect broken buds, and when the broken bud phenomenon is detected, executing a circulation step or a completion step; wherein, The circulation section step includes a tailing step, and the tailing step includes secondary charging: according to the amount of residual material in the crucible, the raw material to be supplemented is fed into the crucible from the feeding port on the side of the single crystal furnace by the conveying device, and in the secondary charging step, the previously formed crystal rod is lifted to the auxiliary chamber of the single crystal furnace for pressure maintenance; The steps of the finishing section include: after the crystal breaks, when the amount of remaining material in the crucible is less than or equal to 50kg, stopping the furnace; or, after the crystal breaks, when the amount of remaining material in the crucible is greater than 150kg, taking the formed crystal rod out of the single crystal furnace and continuing to lead it out; or, after the crystal breaks, when the amount of remaining material in the crucible is greater than 50kg and less than or equal to 150kg, continuing to perform the equal diameter step.

10. The automated crystal pulling method according to claim 1, characterized in that: The single crystal furnace is provided with a feeding mechanism, which includes a material guide barrel and a vibration component. The material guide barrel is provided in the single crystal furnace and extends from the feeding port into the interior of the single crystal furnace so that the material outlet of the material guide barrel is located above the crucible. The vibration component is in transmission connection with the material guide barrel and is used to drive the material guide barrel to vibrate. In the step of feeding, the raw material is delivered to the material guide barrel by the conveying device, and then the vibration component is used to drive the material guide barrel to shake the received raw material into the crucible. and / or, The determining whether the welding is completed according to the seed crystal aperture specifically includes: determining that the welding is completed when the seed crystal aperture is slightly reduced by 1.2 to 1.5 mm.