System and method for adjusting the axial direction of a single crystal growth apparatus

Abstract

An axial direction adjustment system for a purification furnace according to one embodiment may include an X-ray generator that irradiates X-rays in real time onto a crystal being grown as a single crystal, a sensor unit that detects X-rays reflected from the crystal, a control unit that calculates the full width at half maximum (FWHM) of a rocking curve generated by analyzing X-rays acquired from the sensor unit and generates a command to control the direction of a rotation axis connected to the single crystal according to the result of the calculated full width at half maximum, and an adjustment unit that adjusts the rotation axis based on the control command of the control unit.

Description

Technology Field

[0001] The present invention relates to a system and method for adjusting the axial direction of a purification furnace, and more specifically, to an apparatus and method for evaluating the crystal orientation of a growing single crystal in real time through X-ray diffraction analysis and finely adjusting the axial direction of the purification furnace accordingly. Background Technology

[0002] Single crystals are high-purity crystalline structures critically utilized in electronic devices, semiconductors, and optical devices, and crystal purity and orientation serve as critical quality factors during the manufacturing process. Particularly in the semiconductor industry, the crystal orientation of single-crystal wafers is directly linked to device performance, thus requiring advanced control technology. The purification process is a method of growing single crystals by locally heating and melting solid raw materials using high-temperature heaters, bringing a seed crystal into contact with the molten material, and slowly withdrawing it. This method can be implemented using various techniques, such as the Bridgman-Stockbarger method or the Czochralski method, and high-quality single crystals can be produced through precise control of growth rate, rotation speed, temperature gradient, and atmosphere. In particular, the temperature gradient is critical for controlling the defect density of the single crystal, as it significantly influences the shape of the crystal growth interface and the distribution of thermal stress. Furthermore, controlling the inert gas atmosphere minimizes the incorporation of impurities and allows for the maintenance of the crystal's stoichiometric ratio.

[0003] Single crystals grown through a purification furnace must have their quality guaranteed by verifying the presence of defects such as dislocations, bubbles, cracks, and precipitates; for this purpose, destructive testing techniques have generally been utilized. Destructive testing is a method that involves applying mechanical or chemical action to a single crystal to expose its internal structure, after which defects are identified through microscopic observation or chemical analysis; its reliability is generally high. For example, dislocation density can be measured via optical microscopy after etching, or crystal defects can be analyzed using X-ray diffraction topography. However, this method has limitations in that it damages the single crystal being inspected, rendering it unusable as a final product. The losses resulting from destructive testing are particularly significant for expensive rare-earth or semiconductor single crystals. Furthermore, since this inspection can only be applied after the single crystal growth process is complete, it has the disadvantage of making real-time quality monitoring impossible. While defects occurring during the growth process can be improved by changing growth conditions, immediate response is difficult due to the long time required for destructive testing results to be obtained.

[0004] Non-destructive testing technology is gaining attention as a method to overcome the limitations of such destructive testing. By installing an analysis device in a purification furnace to analyze the crystal orientation of growing single crystals in real time, immediate adjustments can be made in the event of defects, which is effective for quality improvement. Non-destructive testing methods include X-ray diffraction (XRD), Raman spectroscopy, and ultrasonic microscopy, which can be utilized to analyze the structural characteristics, chemical composition, and elastic properties of crystals. In particular, X-ray diffraction analysis can precisely measure the lattice constant, crystal orientation, and crystallinity of crystals, making it suitable for real-time monitoring. However, existing X-ray diffraction analysis systems require precise position control and data analysis techniques, and have the disadvantage of high equipment size and cost.

[0005] Conventional technology refers to technical information that the inventor possessed for the derivation of the present invention or acquired during the process of deriving the present invention, and it cannot necessarily be considered publicly known technology disclosed to the general public prior to the filing of the present invention. Prior art literature

[0006] Republic of Korea Published Patent Application No. 10-2024-0177734 (Published Dec. 27, 2024) Republic of Korea Registered Patent Application No. 10-2385259 (Registered Apr. 6, 2022) The problem to be solved

[0007] In resolving the aforementioned problems, the objective of the present invention is to provide a system and method for adjusting the axial direction of a purification furnace that enables stable growth of high-quality single crystals with a small full width at half maximum (FWHM) while maintaining the parallelism of crystal planes, by evaluating the quality and orientation of the crystal in real time through X-ray diffraction analysis during the single crystal growth process and finely adjusting the rotation axis of the purification furnace based on the results.

[0008] The problems that the present invention aims to solve are not limited to those mentioned above, and other problems not mentioned will be clearly understood by a person skilled in the art to which the present invention belongs from the description below. means of solving the problem

[0009] An axial direction adjustment system for a purification furnace according to one embodiment may include an X-ray generator that irradiates X-rays in real time onto a crystal being grown as a single crystal, a sensor unit that detects X-rays reflected from the crystal, a control unit that calculates the full width at half maximum (FWHM) of a rocking curve generated by analyzing X-rays acquired from the sensor unit and generates a command to control the direction of a rotation axis connected to the single crystal according to the result of the calculated full width at half maximum, and an adjustment unit that adjusts the rotation axis based on the control command of the control unit.

[0010] According to one embodiment, an X-ray generating unit and a sensor unit are each arranged in pairs along two mutually orthogonal directions with respect to the growth direction of the single crystal, and can be installed to correspond to the position where the single crystal grows within the purification furnace.

[0011] According to one embodiment, the adjustment unit may include a first actuator for adjusting the vertical angle in the horizontal direction of the rotation axis and a second actuator for adjusting the vertical angle in the vertical direction of the rotation axis.

[0012] According to one embodiment, the control unit calculates the half-width in the direction corresponding to the X-ray generator, and if the half-width is greater than or equal to a preset reference value, it can adjust the vertical angle of the rotation axis in the corresponding direction.

[0013] According to one embodiment, the control unit can automatically correct the rotation axis by using an algorithm that determines the direction in which the half-width of the locking curve is minimized.

[0014] According to one embodiment, when the half-width is greater than or equal to a preset reference value, the control unit of the rotation axis independently calculates the half-width from the locking curve generated in each direction and can individually control the adjustment unit in the horizontal and vertical directions based on each calculation result.

[0015] According to one embodiment, the X-ray generator and sensor unit further include a third X-ray generator and a third sensor unit positioned in a different direction from the two existing pairs of X-ray generators and sensor units, and the control unit can adjust the inclination of the third direction of the rotation axis when the half-width of the third locking curve generated based on reflected X-ray data obtained from the third sensor unit is greater than or equal to a reference value.

[0016] According to one embodiment, the control unit can perform non-orthogonal plane correction, which performs corrective rotation in the direction of the Z-axis or an irregular rotation axis when the front is inclined relative to a preset canonical coordinate system (XY plane reference) in order to adjust the inclination of the rotation axis in a third direction, and diagonal direction adjustment, which measures the diffraction response in the third direction away from the existing X and Y direction sensor array to precisely adjust the deviation caused by the complex inclination.

[0017] According to one embodiment, a method for axial adjustment of a purification furnace can be provided, comprising the steps of: irradiating a crystal being grown with X-rays in real time; generating a rocking curve using intensity data of X-rays reflected from the crystal and calculating a full width at half maximum (FWHM) from the rocking curve; generating a control command to adjust the vertical angle of a rotation axis connected to the single crystal based on a result of comparing the calculated full width at half maximum with a reference value; and adjusting the rotation axis according to the control command. Effects of the invention

[0018] As described above, according to the axial adjustment system and method for a purification furnace of the present invention, by acquiring a rocking curve in real time through X-ray diffraction analysis during the growth of a single crystal, it is possible to detect crystal quality abnormalities early and correct them immediately.

[0019] In addition, according to the axial adjustment system and method of the purification furnace of the present invention, parallelism between crystal planes can be maintained by finely adjusting the vertical angle of the rotation axis so that the full width at half maximum (FWHM) of the locking curve is minimized. Accordingly, high-purity single crystals with a small full width at half maximum and excellent crystallinity can be stably manufactured.

[0020] In addition, according to the axial direction adjustment system and method of the purification furnace of the present invention, uniform crystal direction control is possible by independently acquiring half-width data in the horizontal and vertical directions through two X-ray generators and two sensor units arranged perpendicularly to each other, and by precisely controlling two actuators at the bottom of the rotation axis based on this. Furthermore, since multiple X-ray generators can be arranged in multiple directions, high-precision feedback control for multiple axes is also possible, which can provide scalability to next-generation high-purity single crystal production processes.

[0021] Furthermore, according to the axial direction adjustment system and method of the present invention, the axial direction is automatically corrected by analyzing locking curve data in real time, thereby enabling automated quality control without human intervention. This can simultaneously improve production efficiency and crystal yield.

[0022] The effects of the invention are not limited to those mentioned above, and other unmentioned effects will be clearly understood by a person skilled in the art to which the invention pertains from the description below. Brief explanation of the drawing

[0023] FIG. 1 is a diagram schematically illustrating an axial adjustment system for a tablet according to one embodiment. FIG. 2 is a diagram showing the configuration of an axial adjustment system for a tablet according to one embodiment. Figure 3 is a graph showing the change in impurity concentration during single crystal growth according to one embodiment. FIG. 4 is a diagram illustrating the principle of X-ray diffraction analysis according to one embodiment. FIG. 5 is a diagram illustrating the feature of determining the state of a single crystal based on the analysis of a locking curve according to one embodiment. FIG. 6 is a drawing illustrating a feature for finely adjusting the axial direction of a tablet according to one embodiment. FIG. 7 is a flowchart illustrating an axial adjustment method for a tablet according to one embodiment. FIG. 8 is a drawing for explaining the coating layer of the adjustment part according to one embodiment. Specific details for implementing the invention

[0024] In the present invention, the attached drawings may be illustrated with exaggerated expressions to distinguish it from the prior art, ensure clarity, and facilitate the understanding of the technology. Furthermore, the terms described below are defined considering their functions in the present invention; since these terms may vary depending on the intentions or conventions of the user or operator, their definitions should be based on the technical content throughout this specification. Meanwhile, the embodiments are merely exemplary details of the components presented in the claims of the present invention and do not limit the scope of the rights of the present invention; the scope of rights should be interpreted based on the technical concept throughout the specification of the present invention.

[0025] Throughout the specification, when a configuration is described as "including" a configuration, this means that, unless specifically stated otherwise, it does not exclude other configurations but may include additional configurations.

[0026] Furthermore, when it is said that one configuration is "connected," "connected," or "combined" with another configuration, this means that it is not only "directly connected," "directly connected," or "directly combined," but also that there may be cases where it is "connected with another configuration interposed," "connected with another configuration interposed," or "combined with another configuration interposed." On the other hand, when it is said that one configuration is "directly connected," "directly connected," or "directly combined" with another configuration, it should be understood that there is no other configuration in between.

[0027] In addition, when directional terms such as "front," "back," "up," "down," "left," "right," "first end," "other end," and "both ends" are used, they are used exemplarily in relation to the orientation of the disclosed drawings and should not be interpreted restrictively, and when terms such as "first" and "second" are used, they are terms used to distinguish each configuration and should not be interpreted restrictively.

[0028] In order to more clearly explain the features of the embodiments of the present invention, detailed descriptions of matters widely known to those skilled in the art to which the following embodiments pertain are omitted. Additionally, detailed descriptions of parts in the drawings that are unrelated to the description of the embodiments are omitted.

[0029] Hereinafter, embodiments of the present invention will be described in detail with reference to the attached drawings.

[0031] FIG. 1 is a diagram schematically illustrating an axial adjustment system of a purification furnace according to one embodiment, FIG. 2 is a diagram showing the configuration of an axial adjustment system of a purification furnace according to one embodiment, FIG. 3 is a graph showing a change in impurity concentration during single crystal growth according to one embodiment, FIG. 4 is a diagram explaining the principle of X-ray diffraction analysis according to one embodiment, FIG. 5 is a diagram explaining the feature of determining the state of a single crystal based on the analysis of a locking curve according to one embodiment, FIG. 6 is a diagram explaining the feature of finely adjusting the axial adjustment of a purification furnace according to one embodiment, FIG. 7 is a flowchart explaining a method of axial adjustment of a purification furnace according to one embodiment, and FIG. 8 is a diagram explaining the coating layer of the adjustment part according to one embodiment.

[0033] Referring to FIG. 1, the configuration of a closed-loop control system that automatically corrects the angle of the rotation axis to induce high-quality single crystal growth can be confirmed from the operation of the axial direction adjustment system (10) of a purification furnace according to one embodiment.

[0034] According to one embodiment, the crystal puller is a device for growing a single crystal from molten raw material, and the Czochralski process is applied in a typical manner.

[0035] According to one embodiment, a seed crystal located at the bottom of FIG. 1 is a small single crystal having an aligned lattice structure, and as this crystal is slowly withdrawn while in contact with a melt melted by a heater, the crystal structure from the molten raw material is connected to form a high-purity single crystal.

[0036] In particular, the High-pure Crystal is a single-crystal body formed by actually growing from a seed crystal, and is a substantial crystalline region where the device's channel, gate, electrode, and integrated circuit are directly formed. Substantial lattice accumulation errors or distortions are likely to occur from the upper part of the Melt where the High-pure Crystal is formed. Therefore, the X-ray diffraction analysis of the present invention must be performed in the High-pure Crystal section, which is a solidified region where crystals are formed, rather than inside the still-molten Melt. The region that serves as a reference for adjusting the rotation axis angle of the axial adjustment system (10) of the purification furnace is the location where the high-purity single crystal is formed.

[0038] According to one embodiment, the X-ray generating unit (100) may be composed of a filament and a target metal (e.g., Cu, Mo) to perform X-ray diffraction analysis for evaluating the quality of a single crystal in real time.

[0039] According to one embodiment, when current is applied to a filament, negatively charged electrons are thermally emitted and accelerated toward a nearby target metal. The electrons collide strongly with the target metal connected to the positive electrode, and during this collision, electrons in the inner orbits of the target atoms are ejected. As a result, outer electrons in higher energy levels transition to lower orbits, releasing energy equal to the energy difference between the orbits; the emitted substance is X-rays of a specific wavelength. For example, when copper (Cu) is used as a target, short-wavelength X-rays (Cu-Kα rays) of approximately 1.54 Å are generated. These generated X-rays are irradiated onto a growing single crystal and are reflected by atomic planes within the crystal. The single crystal has multiple layers of lattice planes, and the X-rays are reflected along these crystal planes, with some reflected from the surface and some from the inner lattice. X-rays reflected from multiple crystal planes undergo constructive interference when certain conditions (e.g., wavelength λ of the X-ray, distance d between crystal planes, angle of incidence θ) are satisfied, and at this time, a strong diffraction signal is formed.

[0040] These diffraction conditions are expressed as Bragg's law λ = 2d·sinθ as shown in FIG. 4, and the control unit (300) can analyze the reflected X-rays to determine the spacing (d-spacing) and directionality information of the crystal lattice planes, and based on this information, can diagnose the alignment state, distortion, and presence of defects of the crystal planes in real time in a non-destructive manner.

[0041] In particular, the axial adjustment system (10) for purification according to one embodiment can enable control that immediately reflects the crystal quality by applying the analysis during single crystal growth, thereby contributing significantly to the production of high-quality crystals.

[0043] According to one embodiment, the rocking curve is a curve obtained by rocking a sample (single crystal) with respect to a specific crystal plane at a fine angle and measuring the X-ray reflection intensity according to the angle of rotation (θ). This curve reflects the degree of alignment of the crystal plane, and the narrower and sharper the curve (the smaller the half-width), the better the crystallinity. More specifically, the rocking curve varies depending on the alignment state of the crystal plane; generally, the more precisely the crystal planes are parallel, the narrower and sharper (slender) the curve appears, and the less parallel the curve appears wider and blunter (blunt). According to one embodiment, the rocking curve generated by the control unit (300) can subsequently be used as a key indicator for crystal quality evaluation and rotation axis correction control.

[0044] According to one embodiment, the Full Width at Half Maximum (FWHM) of a rocking curve is a value obtained by measuring the difference in angle between the left and right sides at 50% of the curve's intensity. According to one embodiment, the Full Width at Half Maximum is a key indicator that can quantitatively evaluate the parallelism and crystallinity quality of crystal planes, and a smaller Full Width at Half Maximum indicates that the atomic planes are aligned with each other.

[0046] According to one embodiment, the control unit (300) can form a locking curve based on reflection intensity data received from the sensor unit (200) and determine the quality status by comparing it with a reference half-width.

[0047] Furthermore, the control unit (300) can correct the rotation axis in the direction where the half-width is smallest, that is, the angle direction in which the crystal planes are most aligned, in order to optimize the quality of the single crystal. As a result, problems such as lattice distortion and crystal plane tilting that may occur when the crystal growth direction is slightly misaligned can be compensated for in real time. In particular, the control unit (300) according to one embodiment can dynamically control the crystal growth direction by measuring the locking curve in real time during crystal growth and reflecting the measurement result in the adjustment of the rotation axis.

[0048] According to one embodiment, the control unit (300) can be designed to automatically perform the entire flow from generating a locking curve, calculating half-width, comparing with a reference, determining the rotation direction, determining the rotation angle, and generating a control command by processing reflection intensity data received from the sensor unit (200) in real time. Since this operates sequentially according to an algorithm embedded in the control unit (300) or a set threshold-based conditional statement, an automatic correction feedback loop can be completed without separate manual intervention.

[0050] According to one embodiment, the adjustment unit (400) is physically connected to the lower end of the rotation axis and can perform the function of finely adjusting the vertical angle (Tilt) of the rotation axis in the horizontal and vertical directions. Here, the rotation axis may be connected to a holder (Seed Holder or Chuck) that fixes the Seed Crystal, and this holder serves to rotate while withdrawing the growing single crystal (High-purify crystal).

[0051] In one embodiment, the adjustment unit (400) is implemented as a 2-axis actuator or tilt stage and is composed of a micro stepper motor, a piezo actuator, an electromechanical tilt device, etc., so that the rotation axis can be precisely adjusted to the level of several microradians (μrad). Through this, the growth direction of the single crystal can be controlled in real time.

[0053] Referring to FIG. 2, an axial direction adjustment system (10) for a purification furnace according to one embodiment may include an X-ray generator (100) that irradiates X-rays in real time to a crystal being grown as a single crystal, a sensor unit (200) that detects X-rays reflected from the crystal, a control unit (300) that calculates the full width at half maximum (FWHM) of a rocking curve generated by analyzing X-rays obtained from the sensor unit (200) and generates a command to control the direction of a rotation axis connected to the single crystal according to the result of the calculated full width at half maximum, and an adjustment unit that adjusts the rotation axis based on the control command of the control unit (300).

[0054] According to one embodiment, the X-ray generating unit (100) and the sensor unit (200) are each arranged in pairs along two directions orthogonal to each other with respect to the growth direction of the single crystal, and can be installed to correspond to the position where the single crystal grows in the purification furnace.

[0055] More specifically, single crystals are generally grown continuously along a downward or upward direction (Z-axis) in the Czochralski process, and this axis is designed to align with the orientation of the crystal's major crystal planes. In order to accurately measure the lattice plane spacing (d-spacing) and analyze the crystal plane alignment during X-ray diffraction analysis, the installation criteria of the analysis device must be defined based on its relative position to the crystal growth direction.

[0056] Accordingly, the arrangement of at least one X-ray generating unit (100) and at least one sensor unit (200) is determined based on the growth direction of the single crystal, and this standard can contribute to ensuring consistency in the measurement direction and improving the precision of the diffraction data.

[0057] According to one embodiment, the reason why the X-ray generator (100) and the sensor unit (200) are each positioned in two mutually orthogonal directions is explained as follows. Since the crystal planes of a single crystal have various orientations in three-dimensional space, measuring only one direction is insufficient to evaluate the overall alignment state of the crystal planes. Therefore, by positioning the X-ray generator (110, 120) and the sensor unit (210, 220) in two mutually orthogonal directions (X and Y axes), it is possible to precisely analyze complex structural distortions, such as tilting or asymmetry of the crystal planes. In particular, by configuring independent locking curves for each direction, the full width at half maximum (FWHM) for the horizontal and vertical directions can be calculated, which is effective for implementing a closed-loop system capable of 2-axis precision control.

[0058] According to one embodiment, the reason for installing it to correspond to the location where a single crystal grows within the purification furnace is that the accuracy of X-ray diffraction analysis depends on how well the location to be analyzed aligns with the actual growth region of the single crystal. Meaningful crystal plane information and full width at half maximum can be obtained only when X-rays are irradiated to the section where a substantially completed crystal structure is formed (the location immediately after solidification is complete), rather than to the seed contact or melt boundary where the single crystal begins to form.

[0059] Accordingly, the X-ray generating unit (100) and the sensor unit (200) must be positioned to accurately correspond to the height or outflow distance of the section where a single crystal is growing within the purification furnace, thereby ensuring the reliability of real-time quality analysis and direction correction control of the crystal being grown.

[0060] According to one embodiment, the X-ray generator (100) is configured to induce diffraction by irradiating X-rays onto a single crystal and may include a first X-ray generator (110) and a second X-ray generator (120) installed in mutually orthogonal directions. The first X-ray generator (110) irradiates X-rays along the horizontal direction of a single crystal growing in a purification furnace, and the second X-ray generator (120) irradiates X-rays along the vertical direction, thereby enabling real-time evaluation of the alignment state of the crystal planes.

[0061] According to one embodiment, the sensor unit (200) is configured to collect diffracted X-rays reflected from the single crystal to obtain intensity data, and may include a first sensor unit (210) and a second sensor unit (220). The first sensor unit (210) is positioned in a direction corresponding to the first X-ray generator (110) to collect data for generating a horizontal locking curve, and the second sensor unit (220) is positioned in a direction corresponding to the second X-ray generator (120) to collect vertical data, thereby enabling quantitative measurement of the crystal quality for each axis direction.

[0062] According to one embodiment, the control unit (300) is configured to analyze an X-ray diffraction signal received from the sensor unit (200) to generate a locking curve and calculate the full width at half maximum (FWHM) of the curve.

[0063] According to one embodiment, the control unit (300) can generate a control command to adjust the rotation axis angle in the corresponding direction when the half-width exceeds the reference value compared with the reference value stored in the memory (500).

[0064] According to one embodiment, the control unit (300) may include an algorithm that automatically fine-tunes the angle so that the half-width is minimized.

[0065] According to one embodiment, the control unit (300) may include an algorithm that statistically analyzes the direction in which the full width at half maximum (FWHM) decreases based on the change pattern of the full width at half maximum (FWHM) measured over a recent period and finely adjusts the rotation axis angle in that direction.

[0066] According to one embodiment, a statistical-based algorithm may be included, and linear regression and gradient-based adjustment may be used. For example, if the half-width value increases compared to before, the control unit (300) moves the rotation axis angle slightly in the opposite direction, and if the half-width decreases, it repeatedly performs fine adjustment in the same direction, thereby searching for the optimal angle at which the half-width is minimized.

[0067] According to one embodiment, the control unit (300) may include an artificial intelligence-based prediction algorithm. For example, a prediction model based on DNN, LSTM, etc., may be used, which is suitable for non-linear relationships and has high optimal control prediction accuracy.

[0068] According to one embodiment, the control unit (300) may use a neural network model that predicts the optimal rotation axis angle capable of minimizing the full width at half maximum in real time based on various input variables such as the current angle of the rotation axis, the full width at half maximum sequence of the previous time, the single crystal growth time, and the temperature.

[0069] According to one embodiment, an artificial intelligence-based prediction model learns past axis adjustment history and half-width results to automatically calculate optimal conditions for forming high-quality crystals, and thereby the control unit (300) can precisely control the actuators of the adjustment unit (400).

[0070] According to one embodiment, the memory (500) is configured to store information such as a reference half-width value referenced by the control unit (300), past locking curve data, and a control algorithm. According to one embodiment, the memory (500) enables tracking of quality improvement history by recording changes over time of the locking curve.

[0071] According to one embodiment, the communication module (600) is configured to perform data transmission and reception between the control unit (300) and an external device, and can support system status monitoring, remote control, or quality log transmission.

[0072] According to one embodiment, the adjustment unit may include a first actuator for adjusting the vertical angle in the horizontal direction of the rotation axis and a second actuator for adjusting the vertical angle in the vertical direction of the rotation axis.

[0073] According to one embodiment, the adjustment unit (400) is configured to adjust the vertical angle of the rotation axis according to a control command received from the control unit (300), and may include a first actuator (410) and a second actuator (420). By independently adjusting the horizontal rotation axis angle of the first actuator (410) and the vertical rotation axis angle of the second actuator (420), the direction in which the single crystal grows can be controlled in real time.

[0074] According to one embodiment, the control unit (300) calculates the half-width in the direction corresponding to the X-ray generator, and if the half-width is greater than or equal to a preset reference value, it can adjust the vertical angle of the rotation axis in the corresponding direction.

[0075] According to one embodiment, the control unit (300) can automatically correct the rotation axis by using an algorithm that determines the direction in which the half-width of the locking curve is minimized.

[0076] According to one embodiment, the control unit (300) can independently calculate the half-width from the locking curve generated in each direction and, based on each calculation result, individually control the adjustment unit in the horizontal direction and the vertical direction.

[0078] Referring to the graph showing the change in impurity concentration during single crystal growth in Fig. 3, the distribution of impurities between the solid phase (S) and the liquid phase (L) during the crystal growth process can be confirmed.

[0079] According to one embodiment, the horizontal axis (AB) represents the degree of crystal growth progress and may represent, for example, time, the length of the crystal, or the ratio of the grown crystal. Here, specific points (2, 5, 10) represent specific stages of growth progress. According to one embodiment, the vertical axis represents the concentration of impurities.

[0080] Here, curve L represents the change in impurity concentration in the liquid phase (molten liquid), showing a tendency for the impurity concentration in the molten liquid to gradually increase as the crystal grows.

[0081] Here, curve S represents the change in impurity concentration within the solid phase (single crystal), showing that initially, impurities are contained within the crystal at a lower concentration than in the molten liquid, but the concentration increases as growth progresses.

[0082] Here, T1 represents the critical concentration or target concentration, meaning that if the impurity concentration of the grown crystal exceeds this value, it may affect the quality.

[0083] According to one embodiment, the values ​​2, 5, and 10 on the horizontal axis are displayed to compare the impurity concentrations of the solid phase and the liquid phase at a specific growth stage. When analyzed, for example, at the beginning of growth (2), the impurity concentration of the solid phase is much lower than that of the liquid phase, but as growth progresses (10), the difference decreases.

[0084] In conclusion, the graph in Fig. 3 is an equilibrium phase diagram showing the impurity distribution phenomenon between the liquid and solid phases during the single crystal growth process, and can be used to predict changes in impurity concentration within the single crystal as growth progresses and to set optimal growth conditions.

[0086] Figure 4 is a graph illustrating Bragg's Law, which is the core principle of X-ray diffraction (XRD) analysis. According to one embodiment, by using the principle of X-ray diffraction analysis, diffracted X-rays that cause constructive interference under specific conditions can be detected depending on the distance (d) between crystal planes inside the single crystal and the angle of incidence (θ). Through this, the lattice plane alignment state of the single crystal can be quantitatively evaluated, and by analyzing the full width at half maximum of the rocking curve generated as a result in real time, the tilting or non-uniformity of the crystal planes during the crystal growth process can be immediately identified. Accordingly, by adjusting the angle of the rotation axis in real time, it is possible to efficiently grow a high-quality single crystal with excellent inter-plane alignment.

[0087] 1. Penetration and scattering of X-rays within the crystal lattice

[0088] When a parallel X-ray beam, indicated as the incident X-ray in the diagram, enters a crystal lattice composed of regularly arranged atoms, the incident X-rays interact with each atom constituting the crystal lattice and are scattered in all directions. This scattering can appear as if each atom is emitting a new spherical wave.

[0089] 2. Constructive Interference Condition (Bragg's Law)

[0090] X-rays scattered from crystal planes (planes of atoms labeled A, B, and C in the figure) interfere with each other, and under specific conditions, scattered X-rays undergo constructive interference to produce strong diffraction peaks. This condition of constructive interference is Bragg's Law, which is expressed as Equation 1 as follows.

[0091] [Formula 1]

[0092] λ = 2d·sinθ

[0093] Here, λ is the wavelength of the incident X-ray, d is the distance between the crystal planes, and θ (theta) is the angle that the incident X-ray makes with the crystal planes.

[0094] According to one embodiment, the drawing shows a situation in which two parallel X-rays (1 and 2) are scattered from crystal planes A and B, respectively, and for constructive interference to occur, the path difference between the two scattered X-rays (1' and 2') must be an integer multiple of the incident X-ray wavelength λ.

[0095] 3. Path Difference and Bragg Condition

[0096] According to one embodiment, when X-ray 2 is scattered at the junction B, the additional distance traveled compared to X-ray 1 is P'P + P'P'', and when this path difference is calculated using trigonometric functions, it becomes 2dsinθ. Therefore, the condition for constructive interference to occur is that this path difference becomes an integer multiple (nλ) of the wavelength λ, and generally, the case where n=1 is considered as the strongest diffraction peak, so Bragg's law can be expressed as λ=2dsinθ.

[0097] 4. Acquisition of Crystal Structure Information through Diffraction Pattern Analysis

[0098] According to one embodiment, in X-ray diffraction analysis, a diffraction pattern can be obtained by measuring the intensity of X-rays diffracted at various angles θ, and this diffraction pattern contains information about the distance d between crystal planes. Using Bragg's law, the distance d between crystal planes can be calculated from the measured diffraction angle θ and the wavelength λ of the X-rays used.

[0099] In particular, by analyzing the position, intensity, and width of diffraction peaks, various information such as the type of crystal, crystal structure, lattice constant, crystal size, and crystallinity can be obtained. Furthermore, X-ray diffraction analysis measures the distance between crystal lattices by using constructive interference conditions of scattered X-rays incident on a crystal, thereby enabling the analysis of the crystal's structure and characteristics.

[0101] Referring to Fig. 5, if we visually examine the relationship between the locking curve analysis and the crystal plane alignment state, the two curves in the locking curve graph on the left represent the locking curves in different crystal states.

[0102] According to one embodiment, the curve of crystal plane (a) has a narrow and sharp rocking curve, and the half-value is smaller than the reference value. When comparing the actual atomic plane arrangement of (a), it can be seen that the lattice planes are aligned parallel to each other, the crystal quality is excellent, and the diffraction conditions are clear because the atoms are in regular positions.

[0103] On the other hand, the curve of crystal plane (b) had a half-value greater than the reference value, the rocking curve was blunt, and the half-value was greater than the reference value. When comparing the actual atomic plane arrangement of (b), it can be seen that the crystal planes are not parallel to each other and are distorted, and the reflection intensity is dispersed due to the disordered interatomic alignment.

[0104] According to one embodiment, the reference value to which the half-value is compared is a boundary value for determining the quality of the crystal plane, and varies depending on process conditions, material characteristics, application, etc., and can generally be set at a level of 10 to 60 arcsec. For example, SiC semiconductors (power devices) have a reference value of 15 arcsec, GaN single crystals (LEDs, high frequency) have a reference value of 30 arcsec or less, and at the level of general academic samples, a reference value of 100 arcsec may be used, but this is merely illustrative and is not limited thereto.

[0105] More specifically, for example, if the reference value of the half-width exceeds 30 arcsec and appears as 50 arcsec, the control unit determines that the crystal plane is tilted or misaligned and can generate a control command to adjust the rotation axis in the following flow.

[0106] - Input data: Full Width at Half (FWHM) 50 arcsec

[0107] - Baseline: 30 arcsec

[0108] -FWHM > Reference Value : "Not Good"

[0110] According to one embodiment, the control unit (300) can analyze the asymmetry of the locking curve or the direction of center movement to detect which direction of the rotation axis (X or Y axis, or a combination thereof) tilting has occurred. For example, if the half-width obtained from the horizontal direction sensor is normal and the half-width obtained from the vertical direction sensor is 50 arcsec, it can be determined that the Y-axis is tilted. Based on this, the control unit (300) can determine the correction direction in the direction where the half-width is larger (e.g., sending a command to the vertical direction adjustment unit), calculate a fine rotation angle in proportion to the degree (20 arcsec) that the half-width exceeds the reference value, and determine control variables such as the rotation angle θ, rotation speed ω, and the number of correction repetitions n. For example, the control unit (300) can send a +5μrad command to the second actuator (vertical direction tilt actuator), and the adjustment unit (400) can measure the locking curve again to determine whether the reference value is exceeded and repeatedly perform correction.

[0112] Referring to FIG. 6, according to one embodiment, the first X-ray generator (110) is a device that irradiates X-rays in a specific direction (e.g., horizontal direction) of a single crystal and can form a diffraction analysis system together with the first sensor unit (210). The first X-ray generator (110) is positioned in a fixed direction to analyze the diffraction characteristics of X-rays incident on a specific crystal plane (e.g., plane (100) or plane (111)) of the single crystal, and the corresponding first sensor unit (210) can detect reflected X-rays and transmit them to the control unit (300).

[0113] According to one embodiment, the second X-ray generating unit (120) is a device that irradiates X-rays in a direction orthogonal to the first direction of the single crystal (e.g., vertical direction), and can form a separate diffraction analysis system together with the second sensor unit (220).

[0114] According to one embodiment, the reason the first X-ray generator (110) and the second X-ray generator (120) are arranged in a 90-degree orthogonal direction is that tilt or misalignment of the single crystal may occur in two axes (X and Y axes), and by analyzing the locking curves for each of the two mutually orthogonal directions, the three-dimensional crystal alignment state can be determined more precisely.

[0115] According to one embodiment, the control unit (300) can generate a locking curve based on the reflection intensity and diffraction angle information of the reflected first X-ray and the reflected second X-ray received from the first sensor unit (210) and the second sensor unit (220), and calculate the full width at half maximum (FWHM) therefrom to determine the inclination angle of the rotation axis.

[0116] According to one embodiment, the first actuator (410) is a device for finely adjusting the horizontal tilt of a rotation axis and can adjust the rotation axis in the tilt-X direction by operating according to a control command of the control unit (300).

[0117] According to one embodiment, the second actuator (420) is a driving device that finely adjusts the vertical tilt of the rotation axis and can control the rotation axis in the tilt-Y direction according to the command of the control unit (300).

[0118] Here, the reason for configuring the first actuator (410) and the second actuator (420) independently is that tilt distortion occurring in the growth direction of the single crystal can occur independently in the horizontal direction (X) and the vertical direction (Y), respectively. Since it is difficult to precisely control complex tilt changes with a single actuator, applying a dual actuator structure capable of separately correcting the two axis directions enables more precise and stable control of the crystal growth direction.

[0119] According to one embodiment, the axial adjustment system (10) may include at least three diffraction analysis systems (X-ray generator + sensor) so as to be able to adjust the rotation axis more finely.

[0120] For example, if the axial adjustment system (10) includes three diffraction analysis systems, a third X-ray generator (not shown) and a third sensor (not shown) may be added to the existing two diffraction analysis systems, thereby enabling control of the Z-axis or diagonal direction and irregular planes.

[0121] According to one embodiment, the first X-ray generator (110), the second X-ray generator (120), and the third X-ray generator can each irradiate X-rays onto a single crystal from different directions, and the reflected X-rays from each direction can be received in real time by each sensor unit, and the control unit that acquires them can generate three locking curves. In addition, the control unit (300) can independently calculate the half-width of three directions, simultaneously determine the de-axis tilt error, and generate rotation axis control commands for three or more directions. For example, the three directions may include X, Y, Z, or diagonal tilt, and furthermore, if the crystal plane detected by the sensor is tilted relative to a preset canonical coordinate system (XY plane reference), non-orthogonal plane correction can be performed by performing corrective rotation in the Z-axis or irregular rotation axis direction, and diagonal direction adjustment can be performed by measuring the diffraction response in a third direction away from the existing X and Y direction sensor array to precisely adjust the deviation caused by the composite tilt (e.g., XY composite direction).

[0122] More specifically, the control unit (400) may be configured as a 3-axis gimbal system, and may be configured so that three actuators are connected to each axis to enable multi-degree-of-freedom rotational control.

[0124] According to one embodiment, when the axial adjustment system (10) includes three diffraction analysis systems, it is possible to detect irregular tilt (e.g., diagonal tilt) that cannot be captured by conventional two-directional (X, Y) diffraction analysis alone, and to determine the directionality and asymmetry of lattice distortion from multiple angles, thereby improving alignment accuracy to the μrad level, and the control unit (300) can drive an optimal rotation correction algorithm based on a weighted average based on multi-directional analysis. In addition, as a result, diffraction conditions can be monitored for all major directions surrounding the crystal to maintain omnidirectional quality uniformity, and effective results can be obtained not only for simple circular single crystals but also for hexahedral / square cross-section crystals and asymmetric growth bodies.

[0125] According to one embodiment, when the axial adjustment system (10) includes three diffraction analysis systems, it can be used for compound semiconductor growth where three-axis alignment is important (e.g., GaN, SiC), single crystals for manufacturing high-frequency RF devices sensitive to diffraction deviations, and growth of irregularly shaped crystal rods (where multiple faces must be managed simultaneously).

[0127] A method for axial adjustment of a purification furnace according to the method of the axial adjustment system of FIG. 7 can be provided, comprising the steps of: irradiating X-rays in real time to a crystal being grown as a single crystal (S10); generating a rocking curve using intensity data of X-rays reflected from the crystal and calculating a full width at half maximum (FWHM) from the rocking curve (S20); generating a control command to adjust the vertical angle of a rotation axis connected to the single crystal according to the result of comparing the calculated full width at half maximum with a reference value (S30); and adjusting the rotation axis according to the control command (S40).

[0129] According to one embodiment, the adjustment part (400) is highly likely to undergo corrosion when exposed to moisture, ion contamination, and air for a long period of time. Therefore, as shown in FIG. 8, it is desirable to form a coating layer on the surface of the adjustment part (400) to prevent corrosion.

[0130] The above coating layer is coated using a coating composition, and the coating layer using the above coating composition can exhibit a corrosion prevention effect. Specifically, the coating layer is formed on the surface of the metal of the adjustment unit (400) by the above coating layer to prevent external exposure of the metal of the adjustment unit (400), and the metal contains a metal with a higher ionization tendency than the metal of the adjustment unit (400), thereby preventing corrosion of the metal of the adjustment unit (400).

[0132] Specifically, the coating composition of the present invention may comprise a polyimide resin, a compound represented by the following chemical formula 1, an organic solvent, a metal compound, and an amine compound:

[0133] [Chemical Formula 1]

[0134]

[0135] When a coating layer is formed on the surface of the metal of the adjustment unit (400) using the coating composition of the present invention, the adhesion to the metal of the adjustment unit (400) is excellent, so the coating layer is not easily peeled off by external force, and since it includes a metal compound with a higher ionization tendency than the metal of the adjustment unit (400), it can exhibit an excellent corrosion prevention effect.

[0136] Specifically, the polyimide resin was purchased and used as CAS 62929-02-6, and the compound represented by Chemical Formula 1 was purchased and used from Toko Chemical. When the polyimide resin and the compound represented by Chemical Formula 1 are mixed in an organic solvent and used as a coating composition, due to the specific functional groups and structural characteristics contained in each compound, not only can excellent adhesion to the metal of the adjustment part (400) be exhibited, but the viscosity of the coating composition can also be maintained at a certain level to improve moldability and stability.

[0137] The above metal compound acts as an erosion and corrosion inhibitor by blocking contact with moisture, salt, or oxygen. Here, to function as an erosion and corrosion inhibitor, a metal with a higher ionization tendency than iron may be used. That is, metals or alloys such as aluminum (Al), magnesium (Mg), and zinc (Zn) may be used, and zinc (Zn) is mainly used.

[0138] The particle size of the metal compound may be 0.1 to 10 μm. If the particle size of the metal compound is 0.1 μm or larger, the manufacturing cost of the metal compound can be reduced, and if the particle size of the metal compound is 10 μm or smaller, the metal particles can be uniformly dispersed.

[0139] The organic solvent is selected from the group consisting of methyl ethyl ketone (MEK), toluene, and mixtures thereof, and preferably methyl ethyl ketone may be used, but is not limited to the above examples.

[0140] The above amine compound may include modified aliphatic amines or tertiary amines, and specifically, trimethylamine or aniline may be used. The above amine compound is included in the coating composition to prevent cracking or peeling of the coating film. That is, it has an excellent effect of preventing cracking or peeling of the coating film due to use by increasing the adhesion of the coating layer.

[0141] The coating composition may additionally include a stabilizer as an additional additive, and the stabilizer may include a UV absorber, an antioxidant, etc., but is not limited to the above examples and can be used without limitation.

[0142] The coating composition for forming the above coating layer may more specifically include a compound represented by Chemical Formula 1, a compound represented by Chemical Formula 2, an organic solvent, a metal compound, and an amine compound.

[0143] The coating composition may comprise, with respect to 100 parts by weight of an organic solvent, 30 to 50 parts by weight of a polyimide resin, 30 to 50 parts by weight of a compound represented by Formula 1, 20 to 40 parts by weight of a metal compound, and 5 to 15 parts by weight of an amine compound. Within the above range, a synergistic effect of critical significance in the water-repellent effect resulting from the interaction of each component is exhibited, and outside the above range, the synergistic effect decreases rapidly or becomes almost non-existent.

[0144] More preferably, the viscosity of the coating composition is 1500 to 1800 cP. If the viscosity is less than 1500 cP, it flows down when applied to the metal surface of the adjustment part (400), making it difficult to form a coating layer, and if it exceeds 1800 cP, it makes it difficult to form a uniform coating layer.

[0146] [Preparation Example 1: Preparation of Coating Layer]

[0147] 1. Preparation of coating composition

[0148] A coating composition was prepared by mixing a polyimide of CAS 62929-02-6, a compound represented by the following chemical formula 1, zinc, and trimethylamine in methyl ethyl ketone. Meanwhile, each of the above compounds was purchased from Tokyo Chemical and used:

[0149] [Chemical Formula 1]

[0150]

[0151] The more specific composition of the above coating composition is as shown in Table 1 below.

[0153] TX1 TX2 TX3 TX4 TX5 organic solvent 100 100 100 100 100 CAS 62929-02-6 25 30 40 50 55 Compounds represented by Chemical Formula 1 25 30 40 50 55 metal compounds 15 20 30 40 45 amine compounds 1 5 10 15 20

[0154] (Unit weight parts)

[0156] 2. Preparation of the coating layer

[0157] The experiment was conducted using aluminum, a metal material that is prone to corrosion, instead of the metal of the adjustment part (400).

[0158] A coating layer was formed by applying the coating compositions of TX1 to TX5 to one surface of an aluminum plate measuring 10x10cm and then curing it.

[0160] Experimental Example

[0161] 1. Evaluation of surface appearance

[0162] Due to differences in the viscosity of the coating composition, a sensory evaluation was conducted to determine whether a uniform surface was formed after the coating layer was prepared. The evaluation was conducted to assess whether a uniform coating layer was formed, based on the following criteria.

[0163] ○: Formation of a uniform coating layer

[0164] ×: Formation of a non-uniform coating layer

[0166] TX1 TX2 TX3 TX4 TX5 Sensory evaluation × ○ ○ ○ ×

[0168] When forming a coating layer, if the viscosity is below a certain level, flow occurs on the surface of the metal of the adjustment unit (400), and there are many cases where it is difficult to form a uniform coating layer after the curing process. Accordingly, a problem of low production yield may occur. In addition, if the viscosity is too high, it is difficult to apply the composition uniformly, making it impossible to form a uniform coating layer.

[0170] 2. Measurement of Corrosion Characteristics

[0171] To verify corrosion characteristics, an aluminum plate without a coating layer was used as a control, and a corrosion resistance test was conducted using aluminum plates with coating layers of TX1 to TX5.

[0172] The aluminum plate was immersed in a beaker containing a 10 wt% CuCl2 aqueous solution, and the degree of corrosion was checked over time.

[0173] If the generation of hydrogen gas is visually confirmed, it is said to mean that corrosion has occurred, and the occurrence of corrosion was checked for up to 24 hours.

[0174] ○: Corrosion occurrence

[0175] ×: No corrosion occurs

[0177] TX1 TX2 TX3 TX4 TX5 control group Corrosion ○ × × × × ○

[0178] As a result of the above experiment, it was confirmed that hydrogen gas was generated shortly after the control aluminum plate was placed in the beaker, and copper was precipitated in less than 1 hour. In the case of TX1, hydrogen gas was generated after 3 hours, and copper precipitation was confirmed after 6 hours.

[0179] In the case of other coating layers, no corrosion occurred even after 24 hours, confirming that they have an excellent effect in preventing corrosion.

[0181] As described above, the present invention has been explained with reference to the embodiments illustrated in the drawings, but this is merely illustrative, and it should be understood that various modifications and equivalent alternative embodiments are possible based on the ordinary knowledge of the art to which the art belongs. Accordingly, the true technical scope of protection of the present invention is defined by the claims described below and should be determined based on the specific details of the invention described above.

[0183] As described above, the present invention has been explained with reference to the embodiments illustrated in the drawings, but this is merely illustrative, and it should be understood that various modifications and equivalent alternative embodiments are possible based on the ordinary knowledge of the art to which the art belongs. Accordingly, the true technical scope of protection of the present invention is defined by the claims described below and should be determined based on the specific details of the invention described above. Industrial applicability

[0185] The present invention relates to an axial adjustment system and method for a purification furnace, and is applicable to the industrial field of semiconductor manufacturing processes.

[0186] No content Explanation of the symbols

[0187] 100: Axial adjustment system for the refining furnace 100: X-ray generator 110: 1st X-ray generator 120: 2nd X-ray generator 200: Sensor section 210: 1st sensor unit 220: Second sensor unit 300: Control unit 400: Adjustment Department 410: First actuator 420: Second actuator 500: Memory 600: Communication module

Claims

Claim 1 X-ray generator for irradiating X-rays in real time onto a crystal being grown as a single crystal; sensor unit for detecting X-rays reflected from the crystal; control unit for calculating the full width at half maximum (FWHM) of a rocking curve generated by analyzing X-rays acquired from the sensor unit, and generating a command to control the direction of a rotation axis connected to the single crystal according to the result of the calculated full width at half maximum; and adjustment unit for adjusting the rotation axis based on the control command of the control unit; wherein the X-ray generator and the sensor unit are each arranged in pairs along two mutually orthogonal directions with respect to the growth direction of the single crystal and are installed to correspond to the position where the single crystal is grown within the purification furnace, and the adjustment unit includes a first actuator for adjusting the vertical angle in the horizontal direction of the rotation axis; An axial direction adjustment system comprising a second actuator for adjusting the vertical angle in the longitudinal direction of the rotation axis, wherein the X-ray generator and the sensor unit include a third X-ray generator and a third sensor unit positioned in a different direction from the two pairs of X-ray generators and sensor units, and the control unit adjusts at least one of the diagonal direction of the rotation axis, the curved surface inclination direction, the Z-axis inclination, and the non-orthogonal plane when the half-width of the third locking curve generated based on reflected X-ray data obtained from the third sensor unit is greater than or equal to a reference value. Claim 2 delete Claim 3 delete Claim 4 An axial direction adjustment system for a purification furnace according to claim 1, wherein the control unit calculates a half-width in a direction corresponding to the X-ray generator, and if the half-width is greater than or equal to a preset reference value, adjusts the vertical angle of the rotation axis in the corresponding direction. Claim 5 An axial adjustment system for a purification furnace according to claim 1, wherein the control unit independently calculates the half-width from a locking curve generated in each direction of the rotation axis and independently controls the adjustment unit in the horizontal and vertical directions based on the calculation result. Claim 6 An axial direction adjustment system for a purification furnace according to claim 1, wherein the control unit automatically corrects the rotation axis using an algorithm that determines the direction in which the half-width of the locking curve is minimized. Claim 7 delete Claim 8 A method executed in an axial adjustment system of a purification furnace, comprising: irradiating X-rays in real time onto a crystal being grown as a single crystal; detecting X-rays reflected from the crystal; analyzing the detected X-rays to calculate the full width at half maximum (FWHM) of a rocking curve generated, and generating a control command to adjust the vertical angle of a rotation axis connected to the single crystal according to the result of the calculated full width at half maximum; A method for axial adjustment of a purification furnace, comprising: a step of adjusting the rotation axis based on the above control command; wherein the step of irradiating X-rays and the step of detecting X-rays utilize a pair of X-ray generators and sensor units arranged along two mutually orthogonal directions based on the growth direction of the single crystal, the step of adjusting the rotation axis adjusts the vertical angle in the horizontal direction of the rotation axis through a first actuator and adjusts the vertical angle in the vertical direction of the rotation axis through a second actuator, and the step of irradiating X-rays and the step of detecting X-rays utilize a third X-ray generator and a third sensor unit arranged in a different direction from the two pairs of X-ray generators and sensor units; and the step of generating the control command generates a control command that adjusts at least one of the diagonal direction of the rotation axis, the curved surface inclination direction, the Z-axis inclination, and the non-orthogonal plane when the half-width of a third locking curve generated based on reflected X-ray data obtained from the third sensor unit is greater than or equal to a reference value.

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