Crystal growing device
By using a laser heating system and precise temperature control, the problems of low heating efficiency and contamination during crystal growth have been solved, achieving efficient and pure crystal growth.
Patent Information
- Application Number
- CN202511826035.5
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-12-05
- Publication Date
- 2026-02-24
AI Technical Summary
Existing heating methods are inefficient and prone to introducing contamination during crystal growth, which affects crystal quality.
A laser heating system is used to heat the crucible. Multiple lasers are arranged in a ring array around the crucible to independently control the axial heating zones. Precise temperature control is achieved by combining pulse modulation and temperature sensors.
This achieves efficient heating, reduces thermal inertia, avoids contamination of the insulation structure, and improves crystal purity and yield.
Smart Images
Figure CN121556129A_ABST
Abstract
Description
Technical Field
[0001] This application relates to the field of semiconductor technology, and more specifically, to a crystal growth apparatus. Background Technology
[0002] Silicon carbide (SiC) is a third-generation semiconductor material with advantages such as a wide bandgap, high thermal conductivity, high critical breakdown field strength, and high electron saturation drift velocity. It is widely used in electric vehicles, 5G (5th Generation Mobile Communication Technology) base stations (RF devices), aerospace (high-temperature sensors), and other fields, and is experiencing explosive growth. Currently, the industrial-scale growth of silicon carbide mainly uses the PVT (Physical Vapor Transport) method. This method involves physically converting the source material into a gaseous phase (usually through heating and sublimation), then transporting the gaseous material through a temperature gradient to a lower-temperature region, where it condenses and deposits on a seed crystal, thus achieving single-crystal growth. However, the growth conditions for single crystals are demanding; even slight fluctuations in the temperature field can affect crystal quality.
[0003] Most existing heating methods use induction heating and resistance heating. Induction heating utilizes alternating magnetic field eddy currents, resulting in high temperature control delay and large temperature fluctuations. Resistance heating uses radiative heat transfer from graphite heating elements, but the temperature gradient between the heater and the crucible causes attenuation, leading to low efficiency. Furthermore, it requires insulation structures such as graphite felt to achieve the desired growth temperature field. However, these insulation structures are inherently susceptible to corrosion and will gradually corrode during growth, causing temperature field fluctuations, reducing crystal quality, and impurities within the graphite felt may contaminate the crystal.
[0004] Therefore, how to improve the heating efficiency of the crystal growth process has become a technical problem that urgently needs to be solved by those skilled in the art. Summary of the Invention
[0005] The purpose of this application is to disclose a crystal growth apparatus to improve the heating efficiency of the crystal growth process.
[0006] A crystal growth apparatus includes a reaction chamber, a crucible, a laser heating system, and a cooling frame;
[0007] The reaction chamber is used to maintain the gas pressure environment for crystal growth;
[0008] The crucible is disposed in the reaction chamber and is used to contain the crystal raw material. The crucible receives heat from the laser heating system, causing the crystal raw material to sublimate into a gas phase. A seed crystal is disposed on the top of the crucible, which is used to supply the gas phase crystal raw material for condensation.
[0009] The laser heating system includes multiple lasers, which output laser beams to heat the crucible; the laser heating system is mounted on the cooling frame, which is used to cool the laser heating system.
[0010] In one possible implementation, a plurality of lasers in the laser heating system are arranged circumferentially around the crucible to form at least one annular laser array.
[0011] In one possible implementation, the laser spot overlap rate is set in the range of 20% to 35%, whereby the spot overlap rate is the proportion of the area of the laser spots that overlap between adjacent laser outputs to the area of a single laser spot.
[0012] In one possible implementation, the output laser wavelength of the laser is set in the range of 1000nm to 1100nm.
[0013] In one possible implementation, along the axial direction of the crucible, the laser heating system includes at least two independently controlled heating zones, each of which is equipped with multiple lasers, and the laser power of each heating zone is independently adjusted to establish a preset temperature gradient along the axial direction of the crucible.
[0014] In one possible implementation, each of the heating zones includes at least one heating layer, and each heating layer includes a plurality of lasers arranged circumferentially around the crucible.
[0015] In one possible implementation, a controller is also included, which is configured to drive the laser heating system in a pulse modulation mode, and the controller controls the output power of the laser by adjusting the frequency and / or duty cycle of the pulses.
[0016] In one possible implementation, a first temperature sensor is further included, which is used to measure the temperature inside the crucible; the controller is provided with a preset temperature range; the controller is configured to:
[0017] When the feedback temperature from the first temperature sensor is lower than the minimum value of the preset temperature range, the controller increases the duty cycle.
[0018] When the feedback temperature from the first temperature sensor is within the preset temperature range, the controller maintains the duty cycle unchanged;
[0019] When the feedback temperature from the first temperature sensor is higher than the maximum value of the preset temperature range, the controller reduces the duty cycle.
[0020] In one possible implementation, the first temperature sensor is a thermocouple, the top of the crucible is provided with a seed crystal holder, and the seed crystal is disposed on the seed crystal holder; the seed crystal holder has at least one temperature measuring hole, and the first temperature sensor is used to detect the temperature of the temperature measuring hole.
[0021] In one possible implementation, a second temperature sensor is also included for measuring the temperature of the heated surface of the crucible; the second temperature sensor includes multiple infrared temperature measuring devices.
[0022] In one possible implementation, the laser heating system and the cooling frame are disposed between the reaction chamber and the crucible;
[0023] Alternatively, the laser heating system and cooling frame are located outside the reaction chamber, which is made of glass.
[0024] In the crystal growth apparatus disclosed in this application, the crystal raw material is first loaded into the crucible, the reaction chamber is closed, and after the reaction chamber is evacuated, high-purity argon gas is introduced as the growth atmosphere. Then, the laser heating system is started to heat the crucible. After the crystal raw material is heated and sublimated into a gas phase, it condenses and deposits on the seed crystal. After the growth is completed, the power of the laser heating system is slowly reduced or the laser heating system is directly turned off to complete the crystal cooling.
[0025] Compared to related technologies, the crystal growth apparatus disclosed in this application utilizes laser heating. The laser energy is efficiently absorbed by the crucible material, resulting in high heating efficiency and low thermal inertia, enabling rapid temperature increases of several hundred degrees Celsius per minute. Furthermore, it eliminates the need for insulation structures such as graphite felt, avoiding potential contamination introduced by insulation structures and ensuring crystal purity. Attached Figure Description
[0026] To more clearly illustrate the technical solutions in the embodiments or related technologies of this application, the accompanying drawings used in the description of the embodiments or related technologies will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.
[0027] Figure 1 This is a front view of the first crystal growth apparatus disclosed in the embodiments of this application;
[0028] Figure 2 This is a top view of the first crystal growth apparatus disclosed in the embodiments of this application;
[0029] Figure 3 This is a front view of the second crystal growth apparatus disclosed in the embodiments of this application;
[0030] Figure 4 This is a top view of the second crystal growth apparatus disclosed in the embodiments of this application;
[0031] Figure 5 This is a front view of the third crystal growth apparatus disclosed in the embodiments of this application;
[0032] Figure 6 This is a top view of the third crystal growth apparatus disclosed in the embodiments of this application;
[0033] Figure 7 This is a front view of the fourth crystal growth apparatus disclosed in the embodiments of this application;
[0034] Figure 8 This is a top view of the fourth crystal growth apparatus disclosed in the embodiments of this application.
[0035] The attached figures are labeled as follows:
[0036] 100. Reaction chamber;
[0037] 200. Cooling base frame;
[0038] 300. Laser heating system;
[0039] 400. Crucible;
[0040] 500. First temperature sensor;
[0041] 600, Inflation port;
[0042] 700. Second temperature sensor. Detailed Implementation
[0043] The purpose of this application is to disclose a crystal growth apparatus to improve the heating efficiency of the crystal growth process.
[0044] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.
[0045] See Figure 1 and Figure 2 The crystal growth apparatus disclosed in this application includes a reaction chamber 100, a crucible 400, a laser heating system 300, and a cooling frame 200.
[0046] The reaction chamber 100 is a sealed container used to maintain the pressure environment for crystal growth (typically a low vacuum or inert gas environment). The reaction chamber 100 can be a vertical cylindrical shape, made of glass or stainless steel. A stainless steel reaction chamber 100 may have a glass laser viewing window for laser beam input. The reaction chamber 100 is equipped with a gas filling port 600, which connects to a gas pipeline system for evacuation, filling with an inert protective gas (such as argon), and introducing doping gases such as nitrogen as needed.
[0047] The crucible 400, made of high-purity graphite, is placed on a tray within the reaction chamber 100. The crucible 400 contains the crystalline raw material, such as SiC (silicon carbide) powder, and withstands heat transferred from the laser heating system 300, causing the crystalline raw material to sublimate into a gaseous phase. A seed crystal is provided at the top of the crucible 400 for the condensation of the gaseous crystalline raw material.
[0048] The laser heating system 300 includes multiple lasers that output laser beams to heat the crucible 400. The lasers include, but are not limited to, fiber lasers and semiconductor lasers, which can be selected by those skilled in the art based on their needs. Due to the extremely high laser power density, the laser heating system 300 can achieve ultra-high temperature environments exceeding 2000°C. Furthermore, the non-contact heating of the crucible 400 using lasers avoids the volatilization of insulation materials or heating elements in resistance heating and the potential contamination introduced by coupling coils in induction heating, thus improving the quality of the crystal sample.
[0049] The cooling base 200 can be a water-cooled copper mounting base, and the laser heating system 300 is mounted on the cooling base 200. The cooling base 200 can be a set of circulating water chillers to provide forced water cooling for the laser mounting base, ensuring that the laser heating system 300 operates stably in an ambient temperature greater than 1000℃.
[0050] In the crystal growth apparatus disclosed in this application, the crystal raw material is first loaded into the crucible 400, the reaction chamber 100 is closed, the reaction chamber 100 is evacuated and then filled with high-purity argon gas as the growth atmosphere, and then the laser heating system 300 is started to heat the crucible 400. After the crystal raw material is heated and sublimated into a gas phase, it condenses and deposits on the seed crystal. After the growth is completed, the power of the laser heating system 300 is slowly reduced or the laser heating system is directly turned off to complete the crystal cooling.
[0051] Compared to related technologies, the crystal growth apparatus disclosed in this application utilizes laser heating. The laser energy is efficiently absorbed by the crucible material, resulting in high heating efficiency and low thermal inertia, enabling rapid temperature increases of several hundred degrees Celsius per minute. Furthermore, it eliminates the need for insulation structures such as graphite felt, avoiding potential contamination introduced by insulation structures and ensuring crystal purity.
[0052] To achieve uniform heating of the crucible 400, multiple lasers in the laser heating system 300 can be arranged circumferentially around the crucible 400 to form at least one ring laser array. The ring laser array achieves 360° energy input without dead angles from a physical layout perspective. Laser energy acts simultaneously and uniformly on the outer wall of the crucible 400 from all directions, fundamentally eliminating circumferential temperature unevenness caused by unilateral heating. This makes the temperature field inside the crucible 400 more stable and symmetrical, which is beneficial for crystal growth and yields samples with uniform composition and fewer defects.
[0053] In one specific implementation, the laser spot overlap rate can be set within the range of 20% to 35%. The spot overlap rate is the proportion of the area of overlap between laser spots output by adjacent lasers to the area of a single laser spot. For example, if the diameter of the crucible 400 is 300 mm and the laser spot diameter is 15 mm, 90 lasers can be evenly arranged around the circumference of the crucible 400, with a spot overlap rate of approximately 30% and a radial temperature difference ≤ 5℃.
[0054] This design avoids the formation of cold zones not covered by the laser beam between laser spots, thus preventing circumferential temperature streaks on the crucible 400 wall and causing uneven heating. Furthermore, due to the characteristic of laser beam energy being high at the center and low at the edges, this design allows the lower energy points of adjacent spots to overlap, compensating for the energy distribution and forming a continuous and smooth energy band in the circumferential direction. This fundamentally eliminates temperature unevenness caused by spot splicing. The extremely small radial temperature difference effectively reduces crystal growth stress, lowers the density of defects such as microtubes and dislocations, and significantly improves crystal quality and yield.
[0055] The laser's output wavelength is set within the range of 1000nm to 1100nm. The crucible 400 is made of graphite, which exhibits near-blackbody characteristics in the 1000nm-1100nm band, with an absorption rate greater than 90%. This design ensures that laser energy is effectively absorbed by the crucible 400 rather than reflected, thus highly efficiently converting laser energy into heat energy, facilitating high energy efficiency and rapid heating. Furthermore, 1060nm and 1080nm are among the most mature and mainstream industrial wavelengths for high-power fiber lasers and semiconductor lasers. These lasers possess mature technology, high reliability, and long lifespan, thereby guaranteeing the performance and cost-effectiveness of the crystal growth device.
[0056] To create a temperature gradient along the axial direction of the crucible 400, the laser heating system 300 is divided into multiple independently controlled heating zones, each equipped with multiple lasers. Each laser in a heating zone can be connected to an independent drive power supply or powered by a single power supply with multiple independent outputs, ensuring that the controller can individually and precisely adjust the power of each heating zone.
[0057] For example, users can preset three heating zones along the axial direction, with the upper and lower heating zones having lower temperatures and the middle heating zone having the highest temperature. By precisely controlling the power of the heating zones, a temperature gradient of hot in the middle and cold at both ends can be achieved. This design allows users to actively design and shape the desired temperature field within the crucible 400, actively maintaining the most favorable thermal environment for material synthesis. This can significantly reduce problems such as crystal defects, compositional segregation, and internal stress, directly leading to higher yields and superior final material properties.
[0058] Based on the above implementation, each heating zone may include at least one heating layer, and each heating layer includes multiple lasers arranged circumferentially around the crucible 400. For example, 30 heating layers may be arranged along the axial direction of the crucible 400, with three pre-defined heating zones: the top 10 heating layers form the upper heating zone, the middle 10 heating layers form the middle heating zone, and the bottom 10 heating layers form the lower heating zone. This design broadens the application range of crystal growth devices. In the preparation of certain gradient materials, it is necessary to precisely control the axial penetration depth and distribution of heat. By adjusting the number of heating layers in each heating zone, the axial heat-affected zone length of each heating zone can be precisely controlled, thereby customizing the heating area according to the actual process requirements. This design provides a controllable means for synthesizing new materials with different temperature gradients.
[0059] To reduce the energy consumption of the crystal growth apparatus, the laser heating system 300 can output in pulse mode, meaning the laser outputs a segment of laser light at regular intervals (pulse period). The crystal growth apparatus may also include a controller that drives the laser heating system 300 in pulse modulation mode.
[0060] The controller can control the laser's output power by adjusting the pulse frequency and duty cycle. The duty cycle is the percentage of time the laser is on within a pulse period. For example, based on the thermal relaxation characteristics of graphite (the process by which a non-equilibrium thermal system returns to thermal equilibrium after a brief thermal disturbance), the relaxation time of graphite is approximately 120 ms. With a pulse frequency of 10 Hz and a duty cycle of 50%, theoretical calculations suggest that the laser's energy consumption can be reduced by approximately 40% while maintaining the same thermal field. During the laser's off period, the laser consumes almost no energy. Since the formation of the thermal field depends on the average power, a lower total energy input can be used to maintain the same target temperature, thereby reducing the system's total power consumption. Furthermore, the pulsed mode allows the heat on the crucible 400 to become uniform for a short period, which helps prevent continuous heat conduction into the crucible 400 and the crystal interior, preventing crystal cracking caused by excessive thermal stress within the material, thus improving the crystal yield.
[0061] To adjust the laser output power in real time based on the temperature of the crucible 400, the crystal growth apparatus also includes a first temperature sensor 500, which measures the internal temperature of the crucible 400. A preset temperature range is configured within the controller. The controller can employ an IPC (Industrial Personal Computer) or multiple multi-channel PID controllers (Proportional-Integral-Derivative Controllers). The IPC receives the feedback temperature signal and calculates the required power adjustment for each laser, which is then executed by the PID controllers and the lasers. The system has preset target temperature curves for each stage of crystal growth (heating, growth, and cooling).
[0062] When the feedback temperature from the first temperature sensor 500 is lower than the minimum value of the preset temperature range, the controller increases the duty cycle. As the duty cycle increases, the laser is on for a longer period, thus extending the heating time of the crucible 400, and the temperature inside the crucible 400 gradually rises. When the first temperature sensor 500 detects that the temperature inside the crucible 400 is already higher than or equal to the minimum value of the preset temperature range, the controller stops increasing the duty cycle.
[0063] When the feedback temperature from the first temperature sensor 500 is within the preset temperature range, it indicates that the temperature inside the crucible 400 meets the requirements. At this time, the duty cycle is the ideal value, and the controller keeps the duty cycle unchanged.
[0064] When the feedback temperature from the first temperature sensor 500 is higher than the maximum value of the preset temperature range, the controller reduces the duty cycle. Because the duty cycle decreases, the laser's on time is shortened, resulting in a shorter heating time for the crucible 400, and the temperature inside the crucible 400 gradually decreases. When the first temperature sensor 500 detects that the temperature inside the crucible 400 is lower than or equal to the maximum value of the preset temperature range, the controller stops reducing the duty cycle.
[0065] This design achieves high temperature control accuracy through sensor temperature measurement and closed-loop PID control. Regardless of external interference, the system can automatically stabilize the temperature within the set range with minimal fluctuations. This ensures that every production run is conducted under identical temperature conditions. Users can pre-program complete process schemes into the controller, such as programmed temperature rise, segmented heat preservation, and controllable cooling. The system can automatically execute the entire process without manual intervention.
[0066] In one specific implementation, the first temperature sensor 500 is a thermocouple, and a seed crystal holder is provided on the top of the crucible 400, with the seed crystal placed on the seed crystal holder. The seed crystal holder has at least one temperature sensing hole, and the first temperature sensor 500 is used to detect the temperature of the sensing hole. To ensure uniform sampling, multiple temperature sensing holes can be equidistantly arranged at different heights along the axial direction of the seed crystal holder. This design brings the thermocouple as close to the seed crystal as possible, allowing direct measurement of the actual temperature near the crystal growth interface. The thermocouple provides a direct, drift-free, real-time temperature signal, providing a reliable basis for precise temperature control.
[0067] To enable multi-point temperature measurement, the crystal growth apparatus may also include a second temperature sensor 700, such as... Figure 3 and Figure 4 As shown. The second temperature sensor 700 is used to measure the temperature of the heated surface of the crucible 400. The second temperature sensor 700 includes multiple infrared temperature measuring devices. The number of infrared temperature measuring devices can be adjusted according to the required detection accuracy. If high accuracy is required, the number of infrared temperature measuring devices can be increased; if low accuracy is required, the number of infrared temperature measuring devices can be reduced accordingly.
[0068] The second temperature sensor 700 can be a laser pyrometer array, with the same number and layout as the lasers, used to measure local temperatures. Based on the feedback temperature, the laser power in the corresponding area is adjusted to achieve precise, localized temperature control. This design can simultaneously and independently measure the temperature at multiple key locations on the outer wall of the crucible. The system can scan and monitor the entire surface temperature of the crucible 400 in real time, providing a data foundation for precise control.
[0069] Furthermore, the second temperature sensor 700 and the first temperature sensor 500 can be used in combination, such as... Figure 7 and Figure 8 The illustrated implementation scheme of the crystal growth apparatus. The first temperature sensor 500 provides absolute temperature calibration and precise measurement of key points, while the second temperature sensor 700 provides high-resolution surface temperature field distribution. The data from both sensors are fused to form a more accurate and reliable temperature feedback signal.
[0070] The laser heating system 300 and the cooling base 200 can be positioned between the reaction chamber 100 and the crucible 400, such as... Figures 1 to 4 As shown, laser energy is directly irradiated onto the crucible 400 from the light source, improving electro-optical conversion efficiency and reducing operating energy consumption, which is especially crucial for ultra-high temperature applications requiring extreme power. Within the reaction chamber 100, the beam propagates in a uniform medium (vacuum or a specific gas), without any aberrations introduced by transmission elements. This ensures that the optical path from the laser to the crucible 400 maintains optimal original beam quality and extremely high stability, resulting in a more uniform focused beam.
[0071] To facilitate laser cooling and maintenance, the laser heating system 300 and cooling base 200 can be located outside the reaction chamber 100, such as... Figures 5 to 8 As shown. The entire laser heating system 300 is placed outside the reaction chamber 100, isolated from the heating area by a sealed, high-transmittance reaction chamber 100. In this embodiment, the reaction chamber 100 is made of high-transmittance, high-temperature resistant glass (such as quartz glass) to allow the laser beam to penetrate the glass cavity wall and irradiate the graphite crucible.
[0072] This design creates a clean, high-temperature environment, preventing the laser from becoming a potential source of contamination when placed inside the reaction chamber 100 at high temperatures. Maintenance and upgrades can be performed without touching the reaction chamber 100. Quick replacement or repair of the laser heating system 300, cleaning or adjustment of the optical path from outside the reaction chamber 100 greatly simplifies laser cooling and maintenance, and enables further integration of visual monitoring systems (such as high-speed cameras) and AI technologies, achieving in-situ observation and intelligent control of the growth process.
[0073] The terms "first" and "second," etc., used in the specification and claims of this application are used to distinguish different objects, not to describe a specific order, and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature.
[0074] Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover non-exclusive inclusion. For example, a process, method, system, product, or device that includes a series of steps or units may include steps or units not listed, but rather not listed. Additionally, in the description of embodiments in this application, "a plurality of" means two or more.
[0075] In the description of this application, it should be understood that the terms "height", "thickness", "upper", "lower", "top", "bottom", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this application.
[0076] In the description of this application, "multiple" means two or more, and at least one means one, two or more, unless otherwise expressly and specifically defined.
[0077] The above description of the disclosed embodiments enables those skilled in the art to make or use this application. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of this application. Specific technical means in some embodiments may be incorporated, in whole or in part, into another embodiment unless explicitly excluded by another embodiment. Therefore, this application is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.
Claims
1. A crystal growth apparatus, characterized in that, It includes a reaction chamber (100), a crucible (400), a laser heating system (300), and a cooling frame (200); The reaction chamber (100) is used to maintain the gas pressure environment for crystal growth; The crucible (400) is disposed in the reaction chamber (100) for containing crystal raw materials. The crucible (400) receives heat from the laser heating system (300) to sublimate the crystal raw materials into a gas phase. A seed crystal is disposed on the top of the crucible (400) for supplying the gas phase crystal raw materials for condensation. The laser heating system (300) includes a plurality of lasers, which are used to output laser beams to heat the crucible (400); the laser heating system (300) is disposed on the cooling base (200), which is used to cool the laser heating system (300).
2. The crystal growth apparatus as described in claim 1, characterized in that, The plurality of lasers in the laser heating system (300) are arranged circumferentially around the crucible (400) to form at least one annular laser array.
3. The crystal growth apparatus as described in claim 1, characterized in that, The laser spot overlap rate is set in the range of 20% to 35%, and the spot overlap rate is the ratio of the area of the laser spots that overlap between adjacent lasers to the area of a single laser spot.
4. The crystal growth apparatus as described in claim 1, characterized in that, The output wavelength of the laser is set in the range of 1000nm to 1100nm.
5. The crystal growth apparatus as described in claim 1, characterized in that, Along the axial direction of the crucible (400), the laser heating system (300) includes at least two independently controlled heating zones, each of which is equipped with multiple lasers, and the laser power of each heating zone is independently adjusted to establish a preset temperature gradient along the axial direction of the crucible (400).
6. The crystal growth apparatus as described in claim 5, characterized in that, Each of the heating zones includes at least one heating layer, and each heating layer includes a plurality of lasers arranged circumferentially around the crucible (400).
7. The crystal growth apparatus as described in claim 1, characterized in that, It also includes a controller configured to drive the laser heating system (300) in a pulse modulation mode, the controller controlling the output power of the laser by adjusting the frequency and / or duty cycle of the pulses.
8. The crystal growth apparatus as described in claim 7, characterized in that, It also includes a first temperature sensor (500) for measuring the temperature inside the crucible (400); the controller has a preset temperature range; the controller is configured to: When the feedback temperature of the first temperature sensor (500) is lower than the minimum value of the preset temperature range, the controller increases the duty cycle; When the feedback temperature of the first temperature sensor (500) is within the preset temperature range, the controller maintains the duty cycle unchanged; When the feedback temperature of the first temperature sensor (500) is higher than the maximum value of the preset temperature range, the controller reduces the duty cycle.
9. The crystal growth apparatus as described in claim 8, characterized in that, The first temperature sensor (500) is a thermocouple. The top of the crucible (400) is provided with a seed crystal holder, and the seed crystal is placed on the seed crystal holder. The seed crystal holder has at least one temperature measuring hole, and the first temperature sensor (500) is used to detect the temperature of the temperature measuring hole.
10. The crystal growth apparatus as described in claim 1, characterized in that, It also includes a second temperature sensor (700) for measuring the temperature of the heated surface of the crucible (400); the second temperature sensor (700) includes multiple infrared temperature measuring devices.
11. The crystal growth apparatus as described in claim 1, characterized in that, The laser heating system (300) and the cooling base (200) are disposed between the reaction chamber (100) and the crucible (400); Alternatively, the laser heating system (300) and the cooling base (200) are disposed outside the reaction chamber (100), which is made of glass.