PVT system with improved hot zone alignment

Abstract

A physical gas-phase transport system with improved hot zone package alignment includes a first video pyrometer for viewing the center of a first hot zone at one end of the hot zone package. This allows for the measurement of the hot zone package's temperature and provides a first video feed showing the instantaneous position of the hot zone package as it is rotated. A second video pyrometer views a second hot zone viewing window at the other end of the hot zone package to measure the temperature of the hot zone package's center and provide a second video feed showing the hot zone package's instantaneous position as it is rotated. A controller processes the temperature measurements and video feeds and adjusts the system components or settings to correct any misalignment of the hot zone package.

Description

CROSS-REFERENCE TO RELATED REGISTRATIONS

[0001] The present application claims the benefit and priority of the preliminary US patent application No. 63 / 517,207 filed on August 2, 2023, the preliminary US patent application No. 63 / 534,601 filed on August 25, 2023, and the preliminary US patent application No. 63 / 548,949 filed on February 2, 2024, the entire contents of which are hereby incorporated by reference. TECHNICAL AREA

[0002] The present disclosure relates generally to physical vapor transport (PVT) systems and to novel methods for aligning hot zone packets within the system. BACKGROUND

[0003] Unless otherwise stated, the materials described in this section are not prior art for this application and are not recognized as prior art by their inclusion in this section.

[0004] Physical vapor transport systems (PVT) are currently used for the growth of single-crystal semiconductor mass from SiC, AlN, ZnSe, ZnSeTe, CdTe, CdS and ZnTe.

[0005] The orientation of the hot zone package, which includes the support structure (typically a quartz vessel for inductively heated systems), thermal insulation (usually graphite foam and graphite felt), and a graphite crucible for the PVT growth of SiC material, enables reproducible growth. The hot zone package for inductive heating of the PVT reactor is loaded into the system manually, semi-manually, or automatically and is supported by an insulating base, which in turn is supported by a metal base coupled with a ferrofluid feedthrough and a rotary motor to ensure rotation of the hot zone package. Graphite foam components are typically used as padding between the quartz base and the quartz support vessel. Graphite felt is generally used as thermal insulation around the crucible, which contains the SiC seed and starting material.The graphite crucible and insulation are designed to provide one or more viewing windows for measuring the crucible temperature with one or more infrared pyrometers, creating a desired vertical and radial temperature gradient inside the crucible for sublimation growth.

[0006] For accurate crucible temperature measurements, the hot zone pack is aligned with the axis of rotation so that the center of the viewing window is always aligned with the pyrometer's field of view. The accuracy of the hot zone pack's placement is generally determined by the accuracy of its assembly (e.g., wrapping the crucible with insulating material), its placement within the vacuum chamber, and the tolerances of the components being processed. Verification of the hot zone pack's alignment within the chamber and the pyrometer is typically performed at the beginning of the growth process, when the crucible temperature exceeds 1000°C. The pyrometer is equipped with a built-in video camera capable of detecting a video signal from a glowing susceptor.Misalignment of the pyrometer's field of view and the center of the viewing window can significantly influence the apparent temperature reading (averaged over one rotation), resulting in a reading that is considerably higher than the temperature measured at the center. Inconsistencies in temperature readings can lead to poor crystal quality and reduce production yield. For example, a deviation of approximately 5 mm from concentricity in a hot zone package can affect the apparent temperature readings by up to 15° Celsius. SUMMARY

[0007] Existing challenges associated with the foregoing, as well as other challenges, are overcome by the structures and methods disclosed herein for aligning the hot zone for a physical gas phase transport system.

[0008] According to another aspect of the present disclosure, a means is provided for maintaining the mechanical alignment of the hot zone on the base, so that the field of view of the pyrometer is aligned near the center of the viewing window.

[0009] In accordance with one aspect of the present disclosure, a source of visible light is installed outside or inside the vacuum chamber to align or verify the position of the hot zone at room temperature prior to the start of the growth run.

[0010] In aspects of this disclosure, the concentricity of the orientation of a hot zone is verified prior to heating the hot zone to a high temperature, typically above 800° Celsius, using a visible light source, such as an LED or an LED array, illuminating a viewing window. High-intensity visible light from a collimated or near-collimated light source provides sufficient illuminance on the surface of a viewing window for a pyrometer video camera to detect a signal at room temperature. This signal can be used as feedback for fine-tuning the pyrometer position prior to heating the load.

[0011] In other embodiments, the concentricity of a hot zone and a pyrometer is determined in situ by analyzing temperature deviation data or a video signal from a pyrometer camera, and the concentricity of the temperature measurements is corrected by real-time adjustment of the xy position of a pyrometer (or a hot zone support) based on real-time video signal processing.

[0012] In other embodiments, the concentricity of a hot zone and a pyrometer is determined in situ by analyzing an immediate temperature signal, and the concentricity is corrected by real-time adjustment of the xy position of a pyrometer or the hot zone support to minimize fluctuations in the immediate temperature signal.

[0013] In accordance with another aspect of the present disclosure, a method for centering a hot zone packet is described when it is loaded at room temperature into a PVT growing tool that uses a signal from a video camera built into a lower pyrometer. An additional light source can assist by utilizing the video signals from the camera built into the pyrometer at room temperature.

[0014] By centering the hot zone package during loading into the PVT growing tool, any deviation of the hot zone from the axis of rotation can be determined in real time, and fine-tuning can be performed before closing the process chamber end cap. After closing the end cap, rotation of the hot zone package can begin, and the alignment can be further verified using an upper pyrometer.

[0015] In another aspect, the present disclosure relates to the use of an automated charging station that employs autonomous guided vehicles (AGVs) or autonomous mobile robots (AMRs) which transmit feedback on the position of the charge with a PVT tool for fine-tuning the centering.

[0016] In accordance with aspects of the present disclosure, a physical gas-phase transport system is provided, comprising a vacuum chamber with a first viewing window in an upper flange of the vacuum chamber and a second viewing window in a lower flange of the vacuum chamber. A heater is configured to heat the vacuum chamber. A rotating base rotates about an axis of rotation, and a hot zone support is configured to be rotated by the rotating base. A hot zone package is supported by the hot zone support and includes a crucible at least partially enclosed by insulation (106b), as well as a first and a second hot zone viewing window. The first hot zone viewing window is located at a first end of the hot zone package and is adjacent to an open end of the crucible. The second hot zone viewing window is located at a second end of the hot zone package.In some aspects, the second hot zone viewing window can extend through the insulation to a second end of the crucible. A first video pyrometer is positioned so that one field of view of the first video pyrometer sees the first hot zone viewing window through the viewing window in the upper flange of the vacuum chamber. The first video pyrometer measures a first temperature of the hot zone package and provides a first video feed showing the instantaneous positions of the hot zone package as it is rotated. A second video pyrometer is positioned so that it looks through the viewing window in the lower flange of the vacuum chamber at the second hot zone viewing window. The second video pyrometer measures a second temperature of the hot zone package and provides a second video feed showing the instantaneous positions of the hot zone package as it is rotated.A controller is configured to receive and analyze the first and second video feeds in order to determine the concentricity of the first and second hot zone viewing windows relative to the rotation axis of the rotating base.

[0017] In another aspect of this revelation, the physical gas-phase transport system further includes a first source of visible light illuminating the first hot zone viewing window, and a second source of visible light illuminating the second hot zone viewing window.

[0018] In another aspect of this revelation, at least one of the first visible light source or the second visible light source is a collimated, high-intensity source of visible light.

[0019] In another aspect of this revelation, the controller is further configured to store temperature measurements taken when the field of view of the first video pyrometer intersects the first hot zone viewing window of the hot zone package while the hot zone package is being heated but not rotating in the vacuum chamber. Using the first video feed, the controller determines how far the field of view of the first video pyrometer deviates from the axis of rotation of the rotating base. Based on this determination of the field of view of the first video pyrometer from the axis of rotation and on the stored temperature measurements, the controller adjusts a temperature within the vacuum chamber.

[0020] In yet another aspect of this revelation, the controller is further configured to use the first video feed to determine how far the field of view of the first video pyrometer deviates from the rotational axis of the rotating base, and to adjust the position of the first video pyrometer. In some aspects, the controller adjusts the position of both the first and second video pyrometers.

[0021] In yet another aspect of this revelation, the controller is further configured to use the first video feed to determine how far the field of view of the first video pyrometer deviates from the center of the first hot zone viewing window, and to adjust the position of the first video pyrometer so that the field of view of the first video pyrometer is aligned with the center of the first hot zone viewing window.

[0022] In yet another aspect of this revelation, the controller is further configured to determine whether the hot zone package in the vacuum chamber is tilted by: determining, using the first video feed, how far the field of view of the first video pyrometer deviates from the axis of rotation of the rotating base; determining, using the second video feed, how far the field of view of the second video pyrometer deviates from the axis of rotation of the rotating base; and comparing how far the field of view of the first video pyrometer deviates from the axis of rotation of the rotating base relative to how far the field of view of the second video pyrometer deviates from the axis of rotation of the rotating base.

[0023] In yet another aspect of this revelation, the controller is further configured to rotate the rotating base and, using the first video pyrometer, capture multiple snapshots of the first hot zone viewing window over one revolution of the hot zone package. From these multiple snapshots, the controller can determine any deviation of the hot zone package's position from the center of the rotating base. If the controller determines that the maximum deviation of the hot zone package's position from the center of the rotating base exceeds a threshold value, the hot zone package's position is adjusted.

[0024] In another aspect of this revelation, the controller is further configured to receive and analyze the first temperature of the center of the first hot zone viewing window and the second temperature of the center of the second hot zone viewing window, and to establish and maintain a desired temperature gradient between the open end of the crucible and a second end of the crucible within the vacuum chamber. In some aspects, the controller can establish and maintain the desired temperature gradient within the vacuum chamber by adjusting the position of the heater. In other aspects, the controller can establish and maintain the desired temperature gradient within the vacuum chamber using a PID (proportional-integral-derivative) control loop.

[0025] In another aspect of this revelation, the physical gas-phase transport system further includes a motion stage configured to adjust a position of the rotating base within the vacuum chamber, a motion stage configured to adjust a position of the first video pyrometer relative to the vacuum chamber, and / or a motion stage configured to adjust a position of the second video pyrometer relative to the vacuum chamber.

[0026] In another aspect of this disclosure, the physical gas phase transport system further includes a cushion arranged between the hot zone support and the rotating base, and a centering lock configured to center the cushion with respect to the hot zone support and to reduce the slippage of the hot zone support relative to the rotating base.

[0027] In yet another aspect of this revelation, the pad incorporates a recess configured to receive the rotating base, and the pad may also include a recess configured to receive the centering lock. A surface of the hot zone carrier that contacts the pad may be roughened to reduce slippage between the hot zone carrier and the pad.

[0028] In another aspect of this revelation, the rotating base, the hot zone carrier, and the lower flange are movable relative to the vacuum chamber to allow the hot zone package to be loaded onto the hot zone carrier outside the vacuum chamber. In such aspects, the rotating base, the hot zone carrier, and the lower flange can be movable relative to the vacuum chamber to allow the hot zone package to be loaded onto the hot zone carrier outside the vacuum chamber. In such aspects, the physical gas-phase transport system can further include a frame to which a motor is mounted, as well as a rotary drive connecting the rotary motor to the rotating base. A spring-loaded mechanism can be configured to bias the lower flange against an open end of the vacuum chamber.

[0029] Furthermore, the physical gas-phase transport system can include an automated loader configured to dock onto a frame of the physical gas-phase transport system to roughly position the hot zone package relative to the hot zone carrier. The automated loader includes at least two support arms for fine-tuning the position of the hot zone package relative to the hot zone carrier. The automated loader can communicate with a controller configured to perform these fine adjustments to the position of the hot zone package relative to the hot zone carrier.

[0030] In another aspect of this disclosure, a method for operating a physical gas-phase transport system is described. The method involves rotating a pedestal positioned on a motion stage configured to adjust the position of the rotating pedestal within a vacuum chamber. The pedestal supports a hot zone carrier, and the hot zone carrier supports a hot zone package. The method further involves measuring, by means of a video pyrometer, a plurality of instantaneous temperatures of the hot zone over one revolution of the hot zone and determining, by means of a controller, an average temperature value from the plurality of instantaneous temperature measurements over one revolution of the hot zone. The method further involves calculating, by means of the controller, a maximum deviation of the plurality of instantaneous temperature measurements over one revolution of the hot zone from the average temperature value.If the controller determines that the maximum deviation is greater than a threshold, the procedure involves adjusting, by means of the movement stage, the position of the hot zone within the vacuum chamber.

[0031] In yet another aspect of this disclosure, a method for loading a hot zone package into a vacuum chamber of a physical gas-phase transport system is described. The method involves: calibrating, by the controller, the lower and upper video pyrometers so that they are aligned with a center of rotation of a rotating base; docking a loader, which carries the hot zone package, to a frame of the gas-phase transport system; aligning, based on feedback from a controller, the hot zone package with the rotating base and with feedback from the lower and upper video pyrometers; lowering, by the loader, the hot zone package onto a carrier on the rotating base; and retracting the support arms.The procedure further includes: rotating, by the controller, the hot zone package and checking the concentricity of the hot zone package with respect to the rotating base; measuring, by the controller, any radial deviation of a center of the hot zone package from the axis of rotation; determining, by the controller, any variation in the instantaneous positional deviation over one revolution of the hot zone; calculating, by the controller, a maximum deviation from the average value; and determining, by the controller, whether the maximum deviation from the average value is greater than a stored threshold.If the average value is greater than the stored threshold, the procedure further includes grasping the hot zone package with the loader arms to lift it from the carrier, undocking the loader from the frame of the gas-phase transport system, and repeating the above steps for calibrating, aligning, lowering, retracting, rotating, measuring, and determining. If the average value is not greater than the stored threshold, the procedure further includes undocking the loader from the frame of the gas-phase transport system and loading the hot zone package into the vacuum chamber of the physical gas-phase transport system for processing. BRIEF DESCRIPTION OF THE FIGURES

[0032] The aforementioned and other features of this disclosure will become clearer with reference to the following description in conjunction with the accompanying drawings. Provided that these drawings represent only some embodiments in accordance with the disclosure and are therefore not to be considered as limiting its scope, the disclosure is described with additional specificity and detail with reference to the accompanying drawings. Fig. Figure 1 schematically shows an inductively heated physical gas phase transport system in accordance with the present disclosure. Fig. Figure 2 shows an example of a pyrometer camera image of the viewing window taken at room temperature, with the indicator of the pyrometer temperature measurement field of view. Fig. Figure 2A shows another example of a pyrometer camera image of the hot zone viewing window with an indicator for the center of rotation, the center of the pyrometer viewing field, the center of the hot zone viewing window trajectory during rotation, and an area of ​​acceptable centering based on image processing. Fig. Figure 3 schematically shows another physical gas phase transport system in accordance with aspects of the present disclosure. Fig. Figure 4 schematically shows a viewing window in a graphite crucible in accordance with aspects of the present disclosure. Fig. Figure 5A shows a top view of the hot zone viewing window, wherein the pyrometer viewing field is aligned precisely with the center of a viewing window and the center of rotation of the hot zone package in accordance with aspects of the present disclosure. Fig. Figure 5B shows a scenario where a hot zone is still centered around the center of rotation, but the pyrometer field is misaligned with respect to the center of rotation. Fig. Figure 5C schematically shows the case where both a hot zone and a pyrometer are misaligned with respect to the center of rotation. Fig. Figure 6A schematically shows the steady-state temperature setpoint (dashed line), determined by the average temperature during one or more revolutions, and the immediate temperature measurement (solid line) for the scenario in Fig. 5A. Fig. Figure 6B shows the steady-state setpoint (dashed line) and the changing immediate temperature (solid line) caused by the misalignment of a hot zone crucible and a pyrometer. Fig. Figure 6C shows a diagram of temperature measurements taken when the position of the pyrometer viewing field was moved in the x and y directions over the hot zone viewing window of a static (non-rotating) hot zone package. Fig. Figure 7 shows a cross-sectional view of a viewing window with details that schematically represent the factors contributing to the accuracy and consistency of the temperature measurement in accordance with aspects of the present disclosure. Fig. Figure 8 shows a system in which the pyrometer is mounted on an xy motion stage and the hot zone carrier and the rotation arrangement are mounted on an xy motion stage in accordance with aspects of the present disclosure. Fig. Figure 9A is a flowchart showing a control algorithm for improved temperature measurement accuracy and consistency in accordance with aspects of the present disclosure. Fig. Figure 9B is a flowchart showing a control algorithm for improved temperature measurement accuracy and consistency in accordance with aspects of the present disclosure. Fig. Figure 10A schematically shows further details of the load carrier arrangement in a closed chamber position in accordance with aspects of the present disclosure. Fig. 10B schematically shows the load-bearing arrangement of Fig. 10A in a position with the chamber open when the end cap with the load and load carrier mechanism is withdrawn from the process chamber in accordance with aspects of the present disclosure. Fig. Figure 10C schematically shows a hot zone package with a modified lower viewing window in accordance with aspects of the present disclosure. Fig. Figure 10D schematically shows a straight but offset hot zone package within the vacuum chamber in accordance with aspects of the present disclosure. Fig. Figure 10E schematically shows an inclined hot zone package within the vacuum chamber in accordance with aspects of the present disclosure. Fig. Figure 11 shows further details of a load-bearing arrangement in accordance with aspects of the present disclosure. Fig. Figure 12A shows an AGV or AMR carrying a load with support arms in accordance with aspects of the present disclosure. Fig. Figure 12B shows an orthogonal cross-sectional view of a load, illustrating the position of the support arms in accordance with aspects of the present disclosure. Fig. Figure 13 is a flowchart showing the steps of an example algorithm for controlling or regulating the position of the load before lowering it over a quartz support base in the PVT tool according to aspects of the present disclosure. DETAILED DESCRIPTION

[0033] Novel devices and methods for aligning a hot zone within a physical gas-phase transport system are described here. For explanatory purposes, numerous specific details are provided in the following description to facilitate a comprehensive understanding of the present disclosure. However, it will be apparent to a person skilled in the art that the present disclosure can also be put into practice without these specific details.

[0034] The following detailed description refers to the accompanying drawings, which form part of this document. In the drawings, similar symbols generally denote similar components, unless the context indicates otherwise. The illustrative embodiments described in the detailed description and the drawings are not to be considered limiting. Other embodiments may be used and further modifications made without departing from the spirit or scope of the subject matter presented here. It is understood that the aspects of this disclosure, as generally described here and illustrated in the figures, may be arranged, substituted, combined, separated, and designed in a variety of different configurations, all of which are expressly considered here.

[0035] Unless otherwise defined, all terms used herein (including technical and scientific terms) have the same meaning as they are commonly understood by a person skilled in the field to which this disclosure belongs. It is further understood that terms as defined in commonly used dictionaries should be interpreted to have a meaning consistent with their meaning in the context of the relevant prior art and the present disclosure, and not in an idealized or overly formal sense, unless expressly defined as such herein.

[0036] As in Fig. As shown in Figure 1, an inductively heated physical gas-phase transport system according to the present disclosure can include the following: a quartz vacuum chamber 101; an induction coil 102; upper and lower viewing windows 103a and 103b formed in the upper and lower sealing flanges 104a and 104b of the vacuum chamber 101, respectively; a video pyrometer 105 for performing temperature measurements and generating a video feed; a hot zone package 106 comprising a crucible 106a, insulation 106b, and a hot zone viewing window 107 formed in the insulation 106b to allow a view into the interior of the crucible 106a; a hot zone support 108; and a rotating quartz base 109 rotating about a rotational axis “A”, thereby rotating the hot zone package 106. The operation of the system from Fig. 1 can be automatically controlled or regulated (“controlled”) by a programmable logic controller (PLC) or a PC (“controller”) 1000, which controls not only the rotation of the base 109, but also the vertical adjustment of the induction coil 102 (as indicated by arrow “B” in Fig. 1 shown) and other process parameters can be controlled or regulated, but are also capable of image recognition and centering data processing based on the temperature measurements and the video feed from the video pyrometer 105. Fig. Figure 2 shows an example of a pyrometer camera image of the hot zone viewing window 107, taken at room temperature, with the indicator of the pyrometer viewing field 201. As experts reading this disclosure will understand, the position of the hot zone window 107 reflects the position of the hot zone package 106 (and thus of the crucible 106a) relative to the axis of rotation.

[0037] Another pyrometer camera image of the hot zone viewing window 107 is in Fig. 2A with an indicator for the rotation center 201, the center of the pyrometer field of view 202, the center of the trajectory of the hot zone window during rotation 203 and the area of ​​acceptable centering 204, which was determined based on the image recognition and centering data processing performed by the controller 1000.

[0038] Fig. Figure 3 schematically shows possible positions of the visible light sources 31, 32, 33 illuminating a hot zone viewing window 107, so that a camera in the video pyrometer 105 can detect the position of the hot zone viewing window 107 and thus the orientation of the hot zone packet 106. It is understood that only a single light source (e.g., one of the light sources 31, 32, or 33) can be present in the system, although two or more light sources are also possible.

[0039] Fig. Figure 4 schematically shows a viewing window 501 in a graphite crucible 502. When the crucible 502 and the pyrometer 105 (see Fig. 3) When precisely aligned on the rotation axis “A” and vertically aligned, the pyrometer viewing field 503 is located exactly in the center of the viewing window 501, thus enabling very accurate temperature measurement. The pyrometer viewing field can also be shifted to positions 504 or 505 (i.e., the pyrometer viewing field rotates around axes X1 and X2, respectively). Fig. 4) depending on how accurately the hot zone packet is centered on the rotation axis and the center line of the pyrometer.

[0040] Fig. Figure 5A shows a top view of the hot zone viewing window 601 (corresponds to 501 in Fig. 4) wherein the pyrometer viewing field 602 is precisely aligned with the center of the viewing window 601 and the rotation center 603 of the hot zone package.

[0041] Fig. Figure 5B shows a scenario in which the hot zone viewing window 601 is still centered around the pyrometer viewing field 603, but the pyrometer viewing field 602' is misaligned with respect to the center of rotation, so that the pyrometer viewing field 602' follows the trajectory 605 during one rotation of the hot zone packet.

[0042] Fig. Figure 5C schematically shows the case where both a hot zone viewing field and a pyrometer are misaligned with respect to the center of rotation 606. In such a case, the system directly measures the temperature values ​​of a pyrometer viewing field 602, which moves along the trajectory 607 during one rotation of the hot zone package.

[0043] Fig. Figure 6A schematically shows the steady-state temperature setpoint (dashed line), which is determined by the average temperature during one or more rotations of the hot zone package, and the immediate temperature measurement (solid line) for the scenario in Fig. 5A, if both the pyrometer and the hot zone viewing window are precisely centered on the center of rotation, or for the scenario in Fig. 5B, when the hot zone viewing window is perfectly positioned on the center of rotation, but the pyrometer is misaligned. In the scenario in Fig. In the 5B version, the pyrometer measures the temperature at a constant distance from the axis of rotation, so while the measurements are not ideal, they still indicate a steady-state temperature. The Controller 1000 can be programmed to detect variations in the pyrometer's distance from the center of rotation and adjust the power (e.g., the RF power) of a power supply (not shown) accordingly to achieve a desired process temperature.

[0044] Fig. Figure 6B shows the steady-state setpoint (straight dashed line) and the varying immediate temperature (varying solid and dashed lines) caused by misalignment of both a hot zone packet and a pyrometer, as in the scenario in Fig. 5B. The temperature fluctuations ΔT1 and ΔT2 are linearly proportional to the deviation of the trajectory of the pyrometer field of view 607 (see Fig. 5C) from the center of rotation, as long as the pyrometer field of view remains constantly within the hot zone viewing window. In the scenario in Fig. 5C, the pyrometer measures different temperatures at different distances from the axis of rotation; the controller 1000 can be programmed to average either the varying temperatures or the distance that the pyrometer varies during one or more revolutions of the hot zone package from the center of rotation and to adjust the temperature of the system accordingly to achieve a desired process temperature.

[0045] The Controller 1000 can adjust the system temperature based on empirical data stored in a memory (not shown) linked to the 1000. For example, in Fig. As shown in 6C, temperature measurements are taken when the position of the pyrometer viewing field is changed, e.g. by the movement stage 91 (see Fig. 8), is moved in both the x and y directions across the hot zone view window of a static (non-rotating) hot zone package. As in Fig. To see 6°C, a misalignment of 5 mm leads to a temperature fluctuation of 15°C. Considering the parabolic nature of the curve, which is determined by the data in Fig. As shown in 6C, temperature fluctuations can be extrapolated and stored in the memory of the controller 1000. If the controller 1000 knows (e.g., from the video feed) how far the pyrometer's field of view deviates from the axis of rotation, it can use the stored empirical data from Fig. Use 6C to understand how the system temperature needs to be adjusted to achieve a desired process temperature. It goes without saying that temperature measurements via the hot zone viewing window of a static (non-rotating) hot zone package are not suitable for viewing fields of multiple pyrometers (e.g., an upper and a lower pyrometer – see, for example, Fig. 10A-C below) are carried out and such empirical data may be stored in a memory (not shown) linked to the controller 1000 to determine how the position of the pyrometer(s) or the temperature of the system needs to be adjusted to achieve a desired process temperature.

[0046] Fig. Figure 7 shows a cross-sectional view of a hot zone viewing window, with details 801-804 schematically showing factors that contribute to the accuracy and consistency of the temperature measurement, such as flatness (801), roughness (802), concave, round (803) or conical (804) design of the surface of the hot zone viewing window on the inner top surface of the hot zone viewing window immediately adjacent to the crucible 106a. Although four specific surfaces 801-804 are shown, other surface configurations or combinations of the surface features shown are also conceivable.

[0047] Fig. Figure 8 shows the pyrometer 105, which is mounted on the xy-motion stage 91, as well as the hot zone carrier 108 and the rotation assembly 109, which are to be mounted on the xy-motion stage 92. Stage 91 can be used to adjust the pyrometer's field of view so that it coincides with the rotation axis of the hot zone viewing window, e.g., based on the video feed from the pyrometer 105. Stage 92 can be used to adjust the position of the hot zone package so that it coincides with the central axis of the vacuum chamber, e.g., based on the video feed from the pyrometer 105. B. based on the video feed from the pyrometer 105. The xy movement stages are automatically controlled or regulated by a programmable logic controller (PLC) or a PC (“controller”) 1000, which controls or regulates a motor (not shown) to set the position of stages 91, 92 based on information provided to the controllers by one or more sensors or cameras, such asthe video pyrometer 105 (see . Fig. 1) In some aspects, the controller can process such information (e.g., temperature measurements and video feed from video pyrometer 105) and compare it with information stored in a memory (not shown) to which the controller also has access. The controller can control or regulate the position of stages 91 and 92 in any suitable way, which includes, among other things, the control algorithms described below in conjunction with Fig. 9A and Fig. are described in 9B.

[0048] Fig. Figure 9A is a flowchart illustrating a control algorithm 900 for improved temperature measurement accuracy and consistency based on minimizing the instantaneous temperature variation ΔT below a predefined threshold by in-situ adjusting the xy-position of at least one of the pyrometers or the hot zone pack. At 902, a programmable logic controller (PLC) or a PC ("controller") measures the instantaneous temperatures using the upper pyrometer. At 904, the controller records the variation in the instantaneous temperatures during one rotation of the crucible. At 906, the controller calculates the maximum deviation from the average temperature value over one rotation of the hot zone pack containing the crucible. At 908, the controller determines whether the deviation exceeds a threshold. If so, at 910, the controller adjusts the xy-position of the hot zone pack or the pyrometer.If the deviation is not greater than a threshold value, the controller adjusts the process temperature setpoint by a predefined value based on the offset at 912 (see explanation of ). Fig. 6C, supra), and the process returns to 902.

[0049] Fig. Figure 9B is a flowchart illustrating a control algorithm 950 for improved temperature measurement accuracy and consistency based on minimizing the deviation of the pyrometer's field of view from the center of the rotating viewing window below a predefined threshold by in-situ adjustment of the xy-position of the pyrometer or hot zone package. At 952, a programmable logic controller (“controller”) measures any radial deviation of the pyrometer's field of view from the center of the hot zone viewing window. At 954, the controller records all instantaneous temperature fluctuations during one rotation of the hot zone package containing the crucible. At 956, the controller calculates the maximum deviation from the average temperature value over one rotation of the hot zone package. At 958, the controller determines whether the deviation exceeds a threshold. If so, at 960, the controller adjusts the xy-position of the hot zone package or the pyrometer.If the deviation is not greater than a threshold value, the controller adjusts the process temperature setpoint by a predefined value based on the offset at 962 (see explanation of ). Fig. 6C, supra), and the process returns to 952.

[0050] During processing, to support proper mass transport from the Si+C powder feedstock to a single-crystal SiC boule deposited on the nucleus at the top of the crucible, it can be advantageous to establish and maintain a variable temperature gradient in the vacuum chamber. After accurately measuring the top and bottom temperatures of the hot zone package, the controller can be programmed to analyze the temperature measurements obtained from the top and bottom pyrometers and adjust the system settings to establish and maintain a desired temperature gradient in the vacuum chamber. For example, the controller can move the position of a heater (e.g., the induction coil 102) in the direction indicated by arrow "B" in the diagram. Fig. (as specified in 1) adjusts based on pyrometer readings to establish and / or maintain a desired temperature gradient. In some aspects, the controller can use a PID (Proportional-Integral-Derivative) control loop to maintain a predefined vertical temperature gradient between the temperature measured at the center of the first or upper viewing window and the temperature measured at the center of the second or lower viewing window during the process by adjusting the position of the heating element (induction coil) during the process.

[0051] As in Fig. As can be seen in Figure 10A, the hot zone support base 301 rests, while the load carrier assembly is in a closed-chamber position, on a metal base assembly 302, which is supported by the rotary feedthrough 303, which has a lower viewing window 304. The rotary feedthrough 303 includes a ferrofluid feedthrough to allow rotation of the metal base assembly 302 and the hot zone support base 301, on which the hot zone package 106 is positioned. Fig. 10B schematically shows the load carrier arrangement from Fig. 10A is in an open-chamber position when the end cap 104a, with the hot zone package 305 and the hot zone support base 301, is withdrawn from the vacuum chamber 101. The open-chamber position allows for convenient positioning of the hot zone package 106 on the hot zone support base 301. Using the lower video pyrometer 311, the position of the hot zone package 106 relative to the rotation axis “A” of the base assembly 302 can be determined by viewing the lower viewing window 107a.

[0052] In some embodiments, the lower viewing window 107a extends through the insulation 106b to the bottom of the crucible 106a, as in Fig. 10C is shown, which allows a more accurate reading of the temperature of crucible 106a while the hot zone package rotates.

[0053] The position of the hot zone package 106 can be determined at room temperature, either before or after the load carrier assembly is lifted into the vacuum chamber 101. For example, during operation of the system from Fig. 1. The controller 1000 is not only able to control or regulate the rotation of the base arrangement 302 and the vertical movement of the load carrier arrangement into and out of the vacuum chamber 101 (as indicated by the arrow "C" in Fig. (10B shown) but also for image recognition and centering data processing based on the temperature measurements and the video feed from the lower video pyrometer 305. If the positioning of the hot zone package 106 deviates undesirably from axis “A”, the hot zone package 106 can be lifted and repositioned on the base assembly 302 before the vacuum chamber 101 is sealed and before processing begins. Once the load carrier assembly has been lifted into the vacuum chamber 101 and sealed, the position of both the hot zone viewing window 107 and the lower viewing window 107a can be simultaneously monitored by the video pyrometers 105 and 305, respectively, while the hot zone package 106 is rotated.

[0054] If, during simultaneous monitoring of the position of the hot zone viewing window 107 and the lower viewing window 107a, it is determined that the offset of the viewing windows 107 and 107a from the axis “A” is the same above and below (based on image recognition and centering data processing based on the temperature measurements and the video feed from the video pyrometers 105 and 305), it can be concluded that the hot zone package 106 is straight but offset from the axis, as shown in Fig. 10D shown, and the Controller 1000 can make corresponding adjustments to the position of the video pyrometer and / or the hot zone package or adjust the processing temperature. Fig. In Figure 10D, the trajectory during the rotation of the hot zone viewing window 107 (T1) and the trajectory during the rotation of the lower viewing window 107a (T2) are equivalent, indicating a straight but offset scenario. However, if it is determined that the offset to axis "A" is different at the top than at the bottom (based on image recognition and centering data processing based on the temperature measurements and the video feed from the video pyrometers 105 and 305), it can be concluded that the hot zone package 106 is tilted within the vacuum chamber 101, as shown in Figure 10D. Fig. Shown at 10E. Fig. 10E The trajectory during the rotation of the hot zone viewing window 107 (T1) is greater than the trajectory during the rotation of the lower viewing window 107a (T2), indicating a tilting scenario. The tilt of the hot zone package can be tracked by the controller for statistical analysis and process control from run to run. Based on the statistical analysis, the controller can determine an acceptable threshold for the package's tilt. If the package's tilt exceeds the acceptable threshold, the controller can adjust the system's process conditions to reduce the package's tilt below the threshold. If it is not possible to adjust the system's process conditions to reduce the package's tilt below the threshold, the controller can automatically shut down the process.

[0055] As in Fig. As shown in Figure 11, the quartz hot zone support base 401 rests on a metal base assembly 402, which is supported by the shaft 403 with a rotary bushing 415 mounted on the lower sealing flange 404. The rotary bushing 415 includes a ferrofluid bushing to allow rotation of the metal base assembly 402 and the hot zone support base 401, on which the hot zone package 106 is positioned. The load-bearing assembly has a spring-loaded mechanism 405 that supports the aforementioned assembly on the frame part 406. The rotary drive 407 and the rotary motor 408 are also mounted on the frame part 406. A hollow shaft 403 has a transparent window 409. The translation stage 410 carries the lower video pyrometer 411 with a light source 412. The translation stage 410 can provide manual or motorized displacement of the load carrier assembly in the X, Y and Z directions.

[0056] As in Fig. As shown in Figure 12A, an AGV or AMR is carrying a load using the 1502 support arms. The 1501 automated loader can dock to the frame of the PVT tool for rough positioning and features fine adjustment of the 502 support arms for positioning the load before lowering it over a quartz base. The 1501 loader is also capable of communicating with the PVT tool via a wireless interface, such as Wi-Fi, Bluetooth, or similar, to make fine adjustments to the position based on video feedback from the lower pyrometer camera. Fig. Figure 12B shows an orthogonal cross-sectional view of a load, illustrating the position of the support arms 1502. It should be noted that mechanical, vacuum, or other methods can be used to grip and support the quartz load assembly with the support arms 1502. The number of support arms can be one, two, or more, while the number of contact points with the quartz load assembly can be two, four, six, or more.

[0057] Fig. Figure 13 shows a possible algorithm 1100 for controlling or regulating the position of the load before lowering it over a quartz support base in the PVT tool.

[0058] At 1102, the lower and upper pyrometers and the cameras are calibrated to align with the center of rotation. At 1104, the loader, which transports the hot zone package, docks with a PVT tool. At 1106, the loader aligns a hot zone package onto a base, receiving feedback from the lower and upper cameras. At 1108, the loader lowers the hot zone package onto a support base and retracts the support arms. At 1110, the processor (PLC / PC) begins rotating the load to check the concentricity of the hot zone. At 1112, the PLC / PC measures any radial deviation of the hot zone center from the axis of rotation. At 1114, the control loop detects any deviation from the current position during one revolution of the crucible. At 1116, the control loop calculates the maximum deviation from the average value.At 1118, the controller determines whether the maximum deviation from the average value is greater than a stored threshold. If the threshold is exceeded, the process returns to 1102 at 1120, and the charging process is repeated. If the threshold is not exceeded, the charger undocks from the PVT tool at 1122, and the system continues with a growth run.

[0059] The example algorithms in the flowcharts in Fig. 9A, Fig. 9B and Fig. 13 contain various processes, actions, or functions represented by one or more blocks. Although represented as individual blocks, various blocks can be split into additional blocks, combined into fewer blocks, or eliminated, depending on the desired implementation.

[0060] The systems described here can use one or more controllers to receive various pieces of information and transform that information to produce an output. The controller can include any type of computing device, arithmetic circuit, or processor or processing circuit capable of executing a series of instructions stored in memory. The controller can include multiple processors and / or multicore central processing units (CPUs) and can incorporate any type of processor, such as a microprocessor, digital signal processor, microcontroller, programmable logic device (PLD), field-programmable gate array (FPGA), or similar.The controller may also include memory to store data and / or instructions which, when executed by the one or more processors, cause the one or more processors to perform one or more procedures and / or algorithms.

[0061] All procedures, programs, algorithms, or codes described herein can be converted into or expressed in a programming language or computer program. The terms "programming language" and "computer program," as used here, encompass any language used to specify instructions for a computer and include (but are not limited to) the following languages ​​and their derivatives: Assembler, Basic, batch files, BCPL, C, C+, C++, Ladder Logic, Delphi, Fortran, Java, JavaScript, machine code, operating system instruction languages, Pascal, Perl, PL1, scripting languages, Visual Basic, metalanguages ​​that themselves specify programs, and all first-, second-, third-, fourth-, fifth-, or subsequent-generation computer languages. Also included are database and other data schemas, as well as all other metalanguages.No distinction is made between languages ​​that are interpreted or compiled, or that use both compiled and interpreted approaches. No distinction is made between compiled and source versions of a program. A reference to a program where the programming language can exist in more than one state (e.g., source code, compiled, object, or linked) is therefore a reference to all of these states. The reference to a program can include the actual instructions and / or the intent behind those instructions.

[0062] The storage and / or memory device may consist of one or more physical units used to temporarily or permanently store data or programs. In some embodiments, the controller may include volatile memory and requires power to maintain the stored information. In other embodiments, the controller includes non-volatile memory and retains the stored information even when power is not supplied. In some embodiments, the non-volatile memory includes flash memory. In other embodiments, the non-volatile memory includes dynamic random-access memory (DRAM). In other embodiments, the non-volatile memory includes ferroelectric random-access memory (FRAM).In some embodiments, the non-volatile memory includes phase-change random-access memory (PRAM). In some embodiments, the controller is a storage device that includes—as non-limiting examples—CD-ROMs, DVDs, flash memory devices, magnetic disk drives, magnetic tape drives, optical disk drives, and cloud-computing-based storage. In some embodiments, the memory and / or storage device is a combination of devices such as those disclosed herein. The code or instructions contained therein may be represented by carrier-wave signals, infrared signals, digital signals, and other similar signals.

[0063] It is understood that the foregoing description is merely an illustration of the present disclosure. Various alternatives and modifications may be developed by those skilled in the art without deviating from the disclosure. Accordingly, the present disclosure is intended to encompass all such alternatives, modifications, and deviations. The embodiments described with reference to the attached drawings serve only to demonstrate certain examples of the disclosure. Other elements, steps, methods, and techniques that differ only insignificantly from those described above and / or in the attached claims also fall within the scope of the disclosure. QUOTES INCLUDED IN THE DESCRIPTION

[0000] This list of documents cited by the applicant was automatically generated and is included solely for the reader's convenience. The list is not part of the German patent or utility model application. The DPMA accepts no liability for any errors or omissions. Cited patent literature

[0000] US 63 / 517,207

[0001] US 63 / 534,601

[0001] US 63 / 548,949

[0001]

Claims

[1] Physical gas-phase transport system comprising the following: a vacuum chamber (101) comprising a first viewing window (103a) in an upper flange (104a) of the vacuum chamber and a second viewing window (304) in a lower flange (104b) of the vacuum chamber; a heater (102) configured to heat objects inside the vacuum chamber; a rotating base (109) configured to rotate an axis of rotation; a hot zone carrier (108) configured to be rotated by the rotating base; a hot zone package (106) worn by the hot zone carrier and containing the following: a crucible (106a) which is at least partially surrounded by insulation (106b); a first hot zone viewing window (107) at a first end of the hot zone package and adjacent to an open end of the crucible; and a second hot zone viewing window (107a) at a second end of the hot zone package; a first video pyrometer (105) positioned such that a field of view of the first video pyrometer sees the first hot zone viewing window through the viewing window in the upper flange of the vacuum chamber, wherein the first video pyrometer measures a first temperature of the first hot zone viewing window and provides a first video feed showing the instantaneous positions of the hot zone package as it is rotated; a second video pyrometer(305) positioned to look through the viewing window in the lower flange of the vacuum chamber at the second hot zone viewing window, the second video pyrometer measuring a second temperature of a center of the second hot zone viewing window and providing a second video feed showing the instantaneous positions of the hot zone package as it is rotated; a controller configured to receive and analyze the first and second video feeds to determine the concentricity of the first and second hot zone viewing windows relative to the rotation axis of the rotating base. [2] Physical gas phase transport system according to claim 1, further comprising: a first source of visible light (31) illuminating the first hot zone viewing window; and a second source of visible light (412) that illuminates the second hot zone viewing window. [3] Physical gas phase transport system according to claim 2, wherein at least one of the first visible light source or the second visible light source is a collimated, high-intensity visible light source. [4] Physical gas phase transport system according to claim 1, wherein the second hot zone viewing window extends through the insulation to a second end of the crucible. [5] Physical gas phase transport system according to claim 1, wherein the controller is further configured as follows: Storing temperature measurements taken when the field of view of the first video pyrometer crosses the first hot zone viewing window of the hot zone package while the hot zone package is being heated but not rotating in the vacuum chamber; Determine, using the first video feed, how far the field of view of the first video pyrometer deviates from the axis of rotation of the rotating base; Based on determining how far the field of view of the first video pyrometer deviates from the axis of rotation, and on the stored temperature measurements, the temperature within the vacuum chamber is adjusted. [6] Physical gas phase transport system according to claim 1, wherein the controller is further configured as follows: Determine, using the first video feed, how far the field of view of the first video pyrometer deviates from the axis of rotation of the rotating base; Adjusting the position of the first video pyrometer. [7] Physical gas phase transport system according to claim 1, wherein the controller is further configured as follows: Determine, using the first video feed, how far the field of view of the first video pyrometer deviates from the axis of rotation of the rotating base; Adjusting the position of the first and second video pyrometers. [8] Physical gas phase transport system according to claim 1, wherein the controller is further configured as follows: Determine, using the first video feed, how far the field of view of the first video pyrometer deviates from a center of the first hot zone viewing window; Adjusting the position of the first video pyrometer so that the field of view of the first video pyrometer is aligned with the center of the first hot zone viewing window. [9] Physical gas phase transport system according to claim 1, wherein the controller is further configured as follows: Determine whether the hot zone package in the vacuum chamber is inclined by: Determine, using the first video feed, how far the field of view of the first video pyrometer deviates from the axis of rotation of the rotating base; Determine, using the second video feed, how far the field of view of the second video pyrometer deviates from the axis of rotation of the rotating base; and Compare how far the field of view of the first video pyrometer deviates from the axis of rotation of the rotating base, in relation to how far the field of view of the second video pyrometer deviates from the axis of rotation of the rotating base. [10] Physical gas phase transport system according to claim 1, wherein the controller is further configured as follows: Rotating the rotating base; Imaging, by means of the first video pyrometer, a plurality of instantaneous images of the first hot zone viewing window over one revolution of the hot zone packet; Determine, from the plurality of snapshots, every deviation of a position of the hot zone packet from a center of the rotating base; and If the controller determines that the maximum deviation of the hot zone package's position from the center of the rotating base is greater than a threshold, adjust the hot zone package's position. [11] Physical gas phase transport system according to claim 1, wherein the controller is further configured as follows: Receiving and analyzing the first temperature of the center of the first hot zone viewing window and the second temperature of the center of the second hot zone viewing window; and Establishing and maintaining a desired temperature gradient between the open end of the crucible and a second end of the crucible inside the vacuum chamber. [12] Physical gas phase transport system according to claim 11, wherein the controller establishes and maintains the desired temperature gradient within the vacuum chamber by adjusting a position of the heating device. [13] Physical gas phase transport system according to claim 11, wherein the controller establishes and maintains the desired temperature gradient within the vacuum chamber using a PID (proportional-integral derivative) control loop. [14] Physical gas phase transport system according to claim 1, further comprising a motion stage (92) configured to adjust a position of the rotating base within the vacuum chamber. [15] Physical gas phase transport system according to claim 1, further comprising a motion stage (91) configured to adjust a position of the first video pyrometer relative to the vacuum chamber. [16] Physical gas phase transport system according to claim 1, further comprising a motion stage (410) configured to adjust a position of the second video pyrometer relative to the vacuum chamber. [17] Physical gas phase transport system according to claim 1, further comprising: a cushion (402) arranged between the hot zone support and the rotating base; and a centering lock (404) configured to center the pad in relation to the hot zone carrier and to reduce slippage of the hot zone carrier relative to the rotating base. [18] Physical gas phase transport system according to claim 17, wherein the cushion includes a recess configured to accommodate the rotating base. [19] Physical gas phase transport system according to claim 17, wherein the cushion includes a recess configured to accommodate the centering lock. [20] Physical gas phase transport system according to claim 17, wherein a surface (408) of the hot zone support that is in contact with the pad is roughened to reduce slippage between the hot zone support and the pad. [21] Physical gas phase transport system according to claim 1, wherein the rotating base, the hot zone carrier and the lower flange are movable relative to the vacuum chamber to allow the loading of the hot zone package onto the hot zone carrier outside the vacuum chamber. [22] Physical gas phase transport system according to claim 21, further comprising: a frame (406); an engine (408) mounted on the frame; a rotary drive (407) that connects the rotary motor to the rotating base; and a spring-loaded mechanism (405) configured to bias the lower flange against an open end of the vacuum chamber. [23] Physical gas phase transport system according to claim 22, further comprising: an automated loader (501) configured to dock onto the frame (406) of the physical gas phase transport system to roughly position the hot zone package relative to the hot zone carrier, wherein the automated loader includes at least two support arms (502) for fine adjustment in the positioning of the hot zone package relative to the hot zone carrier, the automated loader communicates with a controller configured to make fine adjustments to the position of the hot zone package relative to the hot zone carrier. [24] Method for operating a physical gas-phase transport system, the method comprising: Rotating a base, wherein the base is positioned on a motion stage configured to adjust the position of the rotating base within a vacuum chamber, wherein a hot zone carrier is located on the base, the hot zone carrier carrying a hot zone package; Measuring, by means of a pyrometer, a plurality of instantaneous temperatures of the hot zone packet over one revolution of the hot zone packet; Determine, by a controller, an average temperature value from the majority of instantaneous temperature measurements over one revolution of the hot zone package; Calculate, by the controller, a maximum deviation of the majority of instantaneous temperature measurements over one revolution of the hot zone package from the average temperature value; and If the controller determines that the maximum deviation is greater than a threshold, adjust the movement level to the position of the hot zone package within the vacuum chamber. [25] Method for loading a hot zone packet into a vacuum chamber of a physical gas phase transport system, the method comprising: (a) Calibrating, by the controller, the lower and upper video pyrometers so that they are aligned with the center of a rotating base; (b) Docking a loader carrying the hot zone package to a frame of the gas phase transport system; (c) Aligning, based on feedback from a controller, the hot zone package to the rotating base with feedback from the lower and upper video pyrometers; (d) Lowering, by the loader, the hot zone package onto a support of the rotating base; (e) Retraction of the support arms; (f) Rotating the hot zone package by the controller and checking the concentricity of the hot zone package with respect to the rotating base; (g) Measuring, by the controller, the radial deviation of a center of the hot zone package from the axis of rotation of the rotating base; (h) Determine, by the controller, any deviation from the current position over one revolution of the hot zone package; (i) Calculate, by the controller, a maximum deviation from the average value; (j) Determine, by the controller, whether the maximum deviation from the average value is greater than a stored threshold, wherein if the average value is greater than the stored threshold, the procedure further involves grasping the hot zone package with the arms of the loader to lift the hot zone package from the carrier, undocking the loader from the frame of the gas phase transport system and repeating steps (a) to (j), and If the maximum deviation is not greater than the stored threshold, the procedure further includes undocking the loader from the frame of the gas phase transport system and loading the hot zone package into the vacuum chamber of the physical gas phase transport system for processing.

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