Dynamic counterweight system for crystal growing

Abstract

A crystal growth system includes a rotating seed lift assembly for rotating and lifting a seed crystal supported by a cable. The seed lift assembly includes a spool that rotates to wind the cable around it, thereby raising the cable. As the spool rotates, it moves in an axial direction to prevent displacement of the cable in that direction. The movement of the spool and the rotation of the seed lift assembly induce a deviation of the center of mass of the seed lift assembly relative to its axis of rotation, which can cause undesired movement of the cable and, consequently, the seed crystal. A dynamic counterweight system uses one or more sensors to detect the movement of the seed lift assembly and dynamically controls a motor-driven movable counterweight to counteract these deviations, thus maintaining the center of mass at or substantially aligned with the axis of rotation.

Description

Technical Field

[0001] This invention relates generally to crystal growth equipment, and more specifically to dynamic balance improvement for a type of seed crystal. Prior Technology

[0002] Larger crystals, especially single-crystal ingots, are extremely important in various technological fields. For modern electronic devices, single-crystal silicon is a particularly important raw material for wafers used in various functions, such as integrated circuits and components for photovoltaic panels. A single-crystal structure consists of a continuous lattice without grain boundaries and can be made of a single element or multiple elements (e.g., doped materials).

[0003] One common manufacturing technique for producing single-crystal silicon is the Czochralski method, which involves immersing a seed crystal in a molten bath of material and then slowly pulling it out of the bath while rotating it. However, current technology suffers from inefficiencies due to vibration, imbalance, and other similar problems. If not executed correctly, a failure may occur, and the resulting ingot may be a polycrystalline ingot containing grain boundaries. Since grain boundaries can be problematic for various applications, it may be necessary to melt and regenerate the failed ingot, wasting time and effort. Because single-crystal growth processes typically take a long time (e.g., tens of hours or days), any failure can have a significant impact on production efficiency.

[0004] Improved equipment is needed to efficiently manufacture larger single crystals, such as single-crystal silicon. Summary of the Invention

[0005] A specific embodiment of the present invention relates to a dynamic counterweight system for crystal growth, comprising: a counterweight assembly coupled to a seed crystal lifting assembly, the seed crystal lifting assembly being rotatably coupled to a receiving chamber about a rotation axis and supporting a crystal within the receiving chamber; the counterweight assembly comprising: a movable counterweight axially movable along a counterweight axis between a first position and a second position; and a counterweight actuator operably coupled to the movable counterweight to induce the movable counterweight to move along the counterweight axis in response to a control signal. The control includes: a sensor, a location-based sensor for detecting movement of the seed lift assembly; and a controller operatively coupled to the sensor and the counterweight actuator, the controller being configured to: receive sensor signals from the sensor; generate a control signal based on the received sensor signals; and transmit the control signal to the counterweight actuator, wherein the control signal, when received by the counterweight actuator, induces movement of the movable counterweight to counteract a deviation of the center of mass of the seed lift assembly.

[0006] A specific embodiment of the present invention relates to a crystal growth system, comprising: a furnace tank having a crucible for receiving a melt; a receiving chamber having a lower end coupled to the furnace tank via an isolation valve and a top end coupled to a leveling adapter via a plurality of leveling adapter posts; a crystal suspended in the receiving chamber by a cable along a cable centerline; a seed lifting assembly rotatably coupled to the receiving chamber via the leveling adapter about a rotation axis and having an assembly centroid along the cable centerline, the seed lifting assembly supporting the cable in the growth chamber, the seed lifting assembly having a reel for raising the cable, the reel having a reel centroid that moves relative to the cable centerline when the cable is raised; and a dynamic counterweight system comprising: a counterweight assembly coupled to the seed lifting assembly, the counterweight assembly including: a movable counterweight movable along a counterweight axis. The cable moves axially between a first position and a second position; and a counterweight actuator operatively coupled to the movable counterweight to induce movement of the movable counterweight along the counterweight axis in response to a control signal; one or more sensors positioned to detect movement of the seed lift assembly; and a controller operatively coupled to the one or more sensors and the counterweight actuator, the controller being configured to: receive one or more sensor signals from the one or more sensors; generate the control signal based on the received one or more sensor signals; and transmit the control signal to the counterweight actuator, wherein the control signal, upon being received by the counterweight actuator, induces movement of the movable counterweight to counteract the deviation of the assembly's center of gravity from the cable's centerline, and wherein at least some of such deviations of the assembly's center of gravity from the cable's centerline are caused by the movement of the reel's center of gravity as the cable is lifted.

[0007] A specific aspect of this invention relates to a method for growing a crystal, comprising: lowering a crystal to a melt by means of a cable supported by a seed lift assembly; simultaneously rotating the seed lift assembly about a rotation axis and raising the cable, wherein raising the cable includes: raising the cable by means of movement of a component of the seed lift assembly, wherein the movement of the component causes a shift of the center of mass of the component relative to the rotation axis; and dynamically offsetting the deviation of the center of mass of the seed lift assembly from the rotation axis, wherein dynamically offsetting the deviation includes The method involves: detecting the movement of the seed lift assembly during rotation of the seed lift assembly via one or more sensors; generating a control signal based on the detected movement; transmitting the control signal to a counterweight driver operatively coupled to a movable counterweight axially movable between a first position and a second position along a counterweight axis; and driving the movable counterweight by the counterweight driver in response to receiving the transmitted control signal, wherein driving the movable counterweight includes: inducing the movable counterweight to move by an amount sufficient to counteract the deviation.

[0008] Given the detailed description of various embodiments with reference to the drawings, those skilled in the art will understand additional embodiments and / or configurations of the invention, one of which is briefly described below. Simple Explanation of the Diagram

[0009] This specification refers to the following figures, in which similar element symbols are used in different figures to illustrate similar or analogous components.

[0010] Figure 1 is a schematic diagram of a crystal growth system according to a specific state of the present invention, which has a seed enhancement assembly and a dynamic counterweight system.

[0011] Figure 2 is a front view of a seed enhancement assembly of a specific state according to the present invention.

[0012] Figure 3 is a partial cross-sectional view projection of the front part of a seed enhancement assembly according to a specific state of the present invention.

[0013] Figure 4 is a partial cross-sectional rear view of a seed lifting assembly of a dynamic counterweight assembly according to a specific state of the present invention.

[0014] Figure 5 is a partial cross-sectional and enlarged rear view of a dynamic counterweight assembly according to a specific configuration of the present invention.

[0015] Figure 6 is a graphical projection of one of the counterweights in a dynamic counterweight assembly according to a specific state of the present invention.

[0016] Figure 7 is a schematic top view of a seed lifting assembly according to a specific configuration of the present invention, wherein the spool is in a first spool position and the movable counterweight is in a first counterweight position.

[0017] Figure 8 is a schematic top view of a seed lifting assembly according to a specific configuration of the present invention, wherein the spool is in a second spool position and the movable counterweight is in a second counterweight position.

[0018] Figure 9 is a schematic rear view of a counterweight assembly of a specific type according to the present invention.

[0019] Figure 10 is a schematic diagram of a crystal growth system with a dynamic counterweight system according to a specific state of the present invention.

[0020] Figure 11 is a flowchart depicting one of the procedures for dynamically balancing a seed enhancement according to a specific state of the present invention. Implementation

[0021] Cross-reference to related applications

[0022] This application claims priority to U.S. Provisional Patent Application No. 63 / 183,890, filed May 4, 2021, the entire contents of which are hereby incorporated herein by reference.

[0023] A crystal growth system includes a rotating seed lift assembly for rotating and lifting a seed crystal supported by a cable. The seed lift assembly includes a spool that rotates to wind the cable around it, thereby raising the cable. As the spool rotates, it moves along its axial direction to prevent displacement of the cable from its axial position. The movement of the spool and the rotation of the seed lift assembly induce a deviation of the center of mass of the seed lift assembly relative to its axis of rotation, which can cause undesired movement of the cable and, consequently, the seed crystal. A dynamic counterweight system utilizes one or more sensors to detect the movement of the seed lift assembly and dynamically controls a motor-driven movable counterweight to counteract these deviations, thus maintaining the center of mass at or substantially aligned with the axis of rotation.

[0024] Certain crystal growth techniques (such as the production of single-crystal silicon ingots) utilize a seed crystal suspended above a molten material (e.g., a metalloid, such as silicon) within a sealed enclosure. The seed crystal is lowered to contact the melt, and then raised and rotated in a controlled manner to allow the formation of a nascent ingot of crystalline material (e.g., a growing crystal). As the seed crystal continues to be lifted away from the surface of the melt, the nascent single-crystal ingot continues to grow until it reaches a desired length. The seed crystal and the nascent ingot can be vertically pulled upwards into a receiving chamber above the melt.

[0025] Depending on the final size of the ingot, the crystal growth process can take varying amounts of time. In one example, growing a cylindrical ingot of monocrystalline silicon to a length of approximately 5 to 7 meters can take about two days. During this time, any sufficient disturbance to the system can lead to significant defects in the resulting ingot, potentially resulting in a faulty ingot. A faulty ingot may require remelting and regrowth, which can be very expensive. A specific aspect of this invention relates to an improvement that allows a seed growth system to operate with reduced (e.g., cable) shaking and / or other disturbances.

[0026] To achieve the desired and reproducible results with high efficiency, it is important to provide efficient and precise control over the cables used to suspend, rotate, and elevate the seed crystals and nascent ingots. A seed lifting assembly, located at the top of the receiving chamber, controls the rotation and lifting of the cables. The cables can be withdrawn from the seed lifting assembly at a cable terminal.

[0027] To control rotation, the entire seed lift assembly is rotatably coupled to the receiving chamber so that it can rotate about a rotation axis. The rotation axis may be collinear with the cables exiting the seed lift assembly (e.g., collinear with the cables in the receiving chamber). A base of the seed lift assembly is rotatably coupled to the top of the receiving chamber, such as via an adjusting plate, and is driven (e.g., by a rotary motor) to rotate at a desired speed (e.g., approximately several or tens of revolutions per minute, such as 1 RPM to 40 RPM).

[0028] The seed lift assembly can be coupled to the top of the receiving chamber via an adjusting plate. The adjusting plate serves to establish a precisely level attachment surface for the seed lift assembly. The adjusting plate can be coupled to the top of the receiving chamber via a plurality of leveling transition pins, which can be individually adjusted to achieve a desired levelness (e.g., achieving a minimum tilt of the leveling transition). For example, in some cases a set of three leveling pins may be used, but any number of leveling pins can be used. In some cases, the adjusting plate may support a rotary motor that controls the rotation of the seed lift assembly.

[0029] The mechanism used to elevate the cable is supported by a rotating base of the seed lift assembly and therefore also rotates relative to the receiving chamber. In some cases, the cable can be lifted by a cable winch system comprising a grooved spool or drum that collects (e.g., winds up) the cable in a groove as the spool rotates (e.g., at a speed of approximately tens or several revolutions per minute). The cable winch system can also axially translate the spool along its axis of rotation, so that the cable does not overlap itself during the process and therefore does not shift axially along the axis of rotation of the spool. Thus, throughout the growth process, the spool moves axially from a starting position to an ending position. Furthermore, as additional cable is wound around the spool as the growth process progresses, the total combined mass of the spool and the wound cable increases throughout the growth process. Therefore, from the start to the end of the growth process, the center of mass (CoM) of the spool shifts from a starting position to an ending position. As used herein, unless otherwise indicated, the term "centroid" in relation to a spool refers to the centroid of the spool and any cable wound around it (e.g., a cable that will move axially with the axial displacement of the spool).

[0030] Because the various components of the seed lift assembly have different weights, one or more static counterweights can be coupled to the base of the seed lift assembly at various locations so that the CoM of the seed lift assembly moves to a position aligned with the center of one of the cable terminals and / or the centerline of one of the cables as the cable leaves the cable terminal. In other words, a line extending axially through the center of the cable as it leaves the cable terminal and passes downward through the receiving chamber can be referred to as the cable centerline. The CoM of the seed lift assembly can be positioned somewhere along this line, such as at a location above the center of the cable terminal.

[0031] However, due to the movement of the CoM of the reel as the cable rises, the CoM of the seed lift assembly will generally tend to move away from the cable centerline during the growth process. If the CoM deviates from the cable centerline (or the rotation axis of the seed lift assembly) by more than a critical limit, the seed lift assembly can be considered unbalanced, which may produce undesirable results. If the CoM of the seed lift assembly is not adequately aligned with the cable centerline and / or does not fall on the rotation axis of the seed lift assembly, vibrations and undesirable tracks may be induced in the cable, which can negatively affect the nascent ingot. Therefore, according to the specific form and features of the present invention, a dynamic counterweight system can be used to counteract the deviation of the CoM of the seed lift assembly relative to the cable centerline and / or the rotation axis, thus ensuring that the CoM of the seed lift assembly remains precisely aligned with the cable centerline and / or the rotation axis of the seed lift assembly, or within acceptable tolerances.

[0032] As used herein, within acceptable tolerances and / or with sufficient balance, the centroid distance of the seed crystal lift assembly from the axis of rotation is approximately 0%, 1%, 2%, 3%, 4%, 5%, 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, 95%, 100%, 105%, 110%, 115%, 120%, 125%, 130%, 135%, 140%, 145%, 150%, 155%, 160%, 165%, 170%, 175%, 180%, 185%, 190%, 195%, 200%, 205%, 210%, 215%, 220%, 225%, 230%, 235%, 240%, 245%, and / or 250% of the cable diameter.

[0033] A dynamic counterweight assembly may include a movable counterweight that can move between a first position and a second position (e.g., a first range and a second range). The movable counterweight may be driven by a counterweight actuator. The counterweight actuator may be any suitable device for receiving a control signal and inducing movement of the movable counterweight. In one example, the counterweight actuator may be a motor coupled to a lead screw that, upon rotation, induces sliding movement of the movable counterweight along a counterweight axis. Other counterweight actuators may be used, such as any suitable linear actuator (e.g., a pneumatic actuator, a hydraulic actuator, an electromagnetic actuator, or the like).

[0034] In some cases, a dynamic counterweight assembly may include multiple movable counterweights. In some cases, when multiple movable counterweights are used, each movable counterweight may move along a counterweight axis that is not parallel to the counterweight axes of the other movable counterweights.

[0035] The counterweight actuator may be driven by a controller capable of generating control signals based on sensor signals. The controller or control system may include one or more processors and / or other elements that can be used to generate control signals. Any processor may be a general-purpose or special-purpose processor or a microprocessor. In some cases, the controller may include memory for storing machine-readable instructions executable by one or more processors to perform the functions disclosed herein, such as generating control signals based on received sensor signals. The memory may be any suitable computer-readable storage device or media, such as (for example) a random or serial access memory device, a hard disk drive, a solid-state drive, a flash memory device, etc. The memory may include one or more memory devices. In some cases, the controller may be implemented as or may include an application-specific integrated circuit (ASIC).

[0036] In some cases, the controller is coupled to and / or integrated into the seed lift assembly, but this is not always necessary. In some cases, the controller is separate from the seed lift assembly. In some cases, the controller is implemented using one or more components coupled to and / or integrated into the seed lift assembly, and one or more components external to and / or separate from the seed lift assembly. However, in some cases, the controller is implemented as part of a circuitry already present on the seed lift assembly (e.g., a circuitry used in the operation of a reel motor).

[0037] The controller may generate control signals based on received sensor signals from one or more sensors. Any suitable sensor capable of acquiring data associated with the movement of the seed lift assembly may be used. In some cases, the one or more sensors include a load cell or other force sensor. In some cases, the one or more sensors include an accelerometer. In some cases, the one or more sensors include a rotational sensor or proximity sensor (e.g., a magnetic proximity sensor, such as a reed sensor) for measuring the rotational position of the seed lift assembly relative to the receiving chamber. In some cases, the one or more sensors include an optical sensor (e.g., a laser reflection sensor, a visual or non-visual camera, and the like). In some cases, the one or more sensors include a rotary encoder coupled to a reel to determine the rotational position of one of the reels. In some cases, the one or more sensors include a strain gauge positioned on a top pulley to detect forces applied by the cable and the nascent crystal from a reference frame of the seed lift assembly.

[0038] The controller may receive and process one or more sensor signals to identify a corrective action to be taken. The corrective action includes controlling the counterweight actuator of the dynamic counterweight assembly via a control signal to drive the movable counterweight in a controlled manner. The movable counterweight may be driven to move to a specific position. In some cases, the control signal may cause the movable counterweight to be driven at a specific speed and / or for a specific duration.

[0039] The controller can generate control signals based on the analysis of the sensor signals(s). The analysis of the sensor signals(s) may include analyzing(a number of) currently received sensor signals and, as appropriate,(a number of) historical sensor signals (e.g., historical sensor signals from this crystal growth process and / or historical sensor signals from previous crystal growth processes). The analysis of the sensor signals(s) can be used to determine processed data. The processed data may include: i) the current position of one of the seed-lifting assemblies; ii) the current orientation of one of the seed-lifting assemblies; iii) the estimated deviation of the current CoM of the seed-lifting assembly from one of the rotation axis or cable centerline; iv) the expected deviation of the CoM of the seed-lifting assembly from one of the rotation axis or cable centerline at a future point in time; or v) any combination of i to iv.

[0040] The controller can then use this processed data to generate a control signal. This generated control signal can be designed to counteract a current deviation and / or a anticipated deviation between the CoM of the seed lift assembly and the rotation axis or cable centerline. Therefore, as used herein, the phrase "counteract a deviation" and similar phrases include: i) making an adjustment to reduce a current deviation (e.g., a current distance between the CoM of the seed lift assembly and the rotation axis or cable centerline); and ii) making an adjustment to reduce or minimize a future deviation (e.g., a potential future distance between the CoM of the seed lift assembly and the rotation axis or cable centerline). In other words, "counteract a deviation" may occur in some cases where the deviation has never existed.

[0041] The deviation of the CoM of the seed lift assembly from its axis of rotation or cable centerline may occur due to reel movement or other sources. In some cases, the controller is configured to consider only deviations caused by the reel. In some cases, such as if another type of movable counterweight system is in place, the controller is configured to consider only deviations caused by a source other than the reel. However, in some cases, the controller is configured to attempt to counteract any deviations.

[0042] Therefore, the controller can realize a feedback loop designed to reduce or minimize the undesired deviation of the CoM of the seed booster assembly from its rotation axis or cable centerline.

[0043] As described herein, a dynamic counterweight system can be built into a seed growth apparatus or retrofitted to an existing seed growth apparatus. In some cases, dynamic counterweight systems are particularly suitable for retrofitting due to their ease of installation (e.g., no need to add many additional components, no need to replace important components, and the ability to install some components in various different locations as needed) and the ability to reuse some components for other purposes (e.g., reuse existing sensor and / or controller components).

[0044] In some cases, the dynamic counterweight assembly can be advantageously positioned to help statically counterbalance other components of the seed lift assembly. In a retrofit example, the installation of the dynamic counterweight assembly may involve removing one or more static counterweights as needed, or replacing them(e.g.) with one or more lighter static counterweights, depending on the situation. In some cases, components in the dynamic counterweight assembly (e.g., the counterweight actuator) may be redesigned or repositioned further or closer to the axis of rotation of the seed lift assembly. The selection of the positions of the components of the dynamic counterweight assembly can change the position of the center of mass of the dynamic counterweight assembly relative to the axis of rotation of the seed lift assembly, which can be used to help establish the static balance of the seed lift assembly. However, in some cases, the components of the dynamic counterweight assembly may be installed in other orientations, such as positioning the counterweight actuator further or closer to the axis of rotation of the seed lift assembly.

[0045] In some cases, dynamic counterweights may include one or more limit switches, but this is not always the case. Limit switches are used to identify the end of the travel of the movable counterweight. These limit switches are not used to identify the end of the travel of the reel, but this is not always the case.

[0046] The seed-lifting assembly may include a limit switch assembly for identifying the end point of the reel's travel. This limit switch assembly is mechanically coupled to the reel such that rotation of the reel automatically induces movement of a contact surface that contacts one or more limit switches of the limit switch assembly. In some cases, the mechanical coupling may include a sprocket and chain coupling, but this is not always necessary. A sprocket positioned on the spindle driving the reel may be coupled (e.g., via a chain and gearbox) to a corresponding sprocket driving a belt, chain, or lead screw containing a contact surface. Therefore, rotation of the reel will necessarily include rotation of the reel's spindle, which in turn rotates the sprocket of the limit switch assembly, inducing movement of the contact surface of the limit switch assembly.

[0047] In some cases, the movable counterweight of a dynamic counterweight assembly can be a block, such as one slidably supported in a channel by a set of wheels. The counterweight can be driven by a counterweight actuator (such as a motor that drives a lead screw engaging a nut on the counterweight), such that rotation of the lead screw in one or another direction causes the counterweight to slide within the channel in a first or second axial direction. The counterweight actuator can utilize any suitable controllable actuator. As used herein, a controllable actuator can comprise any type of actuator that can be driven by a control signal (e.g., an electrical or electronic control signal). For example, in some cases, a controllable actuator can comprise a hydraulic actuator (e.g., via a solenoid valve), a pneumatic actuator (e.g., via a pump), an electromagnetic actuator, and / or other such actuators.

[0048] Although this document describes a winch-based lifting system, certain features and characteristics of the present invention can be used to counteract the CoM movement of any movable component of a seed lifting assembly (including other types of seed lifting mechanisms).

[0049] These illustrative examples are given to introduce the general subject matter discussed herein and are not intended to limit the scope of the concepts disclosed. The following paragraphs refer to similar element symbols to indicate similar elements, and the directional descriptions are for illustrative purposes and should not be used to limit the drawings of the invention to describe various additional features and examples. Elements included in the illustrations herein may not be drawn to scale.

[0050] Figure 1 is a schematic diagram of a crystal growth system 100 according to a specific embodiment of the present invention, having a seed enhancement assembly 102 and a dynamic counterweight system. The crystal growth system 100 can be used to grow any suitable crystal, such as a single-crystal silicon-based crystal. The crystal growth system 100 may include a furnace tank 114 in which a crucible 116 is housed. The furnace tank 114 provides heat to the crucible 116. The crucible 116 may initially be filled with a solid material, which may be heated until it forms a melt 112. The crucible 116 may be controlled to rotate in a first direction.

[0051] A receiving chamber 106 may be coupled to the top of the furnace trough 114 via an isolation valve 103. The receiving chamber 106 may extend to any suitable length. A seed lift assembly 102 may be coupled to the top of the receiving chamber 106 via a leveling adapter 105. The leveling adapter 105 may include a leveling adapter plate 109 coupled to the top of the leveling adapter 105 by three leveling adapter pins 111. In some cases, other numbers of leveling adapter pins 111 may be used, such as one, two, or more than three. The leveling adapter pins 111 can be adjusted individually to ensure that the leveling adapter plate 109 is level.

[0052] The seed lift assembly 102 can be rotatably coupled to the leveling adapter plate 109, for example, via a bearing 107. Therefore, the seed lift assembly 102 is rotatably coupled to the receiving chamber 106. A rotary motor 113 controls the rotation of the seed lift assembly 102 about a rotation axis 118 that passes axially through the center of the receiving chamber 106 (and axially through the centerline of the cable 104 within the receiving chamber 106).

[0053] A seed crystal lifting assembly 102 can suspend a cable 104 downwards through a receiving chamber 106 and into a furnace bath 114. A seed crystal 108 is held at one of the distal ends of the cable 104 (e.g., the end furthest from the seed crystal lifting assembly 102). The seed crystal can be a smaller single crystal of the same material as the melt 112.

[0054] The crystal growth system 100 is described as being configured between the start and end of a growth process. At the start of the growth process, the seed lift assembly 102 lowers the cable 104 until the seed crystal 108 contacts the melt 112. The seed lift assembly 102 then steadily raises the seed crystal 108 (e.g., at a speed of approximately a few millimeters, tens of millimeters, or hundreds of millimeters per hour, such as 0 mm / hr to 600 mm / hr), while allowing a nascent ingot 110 to form. To achieve optimal crystal growth, the seed lift assembly 102 can rotate in the opposite direction to the rotation of the crucible 116 while raising the cable 104. As the cable 104 rises, the nascent ingot 110 is pulled out of the melt 112, thereby allowing the new material and the single-crystal structure of the nascent ingot 110 to align and solidify at the bottom of the nascent ingot 110.

[0055] During the growth process, the seed lift assembly 102 raises the cable 104, thereby lifting the nascent ingot 110 into the receiving chamber 106 until the growth process ends. The growth process may end when the nascent ingot 110 reaches a desired length, the material in the crucible 116 is exhausted, the seed lift assembly 102 can no longer raise the cable 104, or in other ways.

[0056] For illustrative purposes, the seed crystal lifting assembly is depicted without a cover or shield. In some cases, a cover or shield may surround the seed crystal lifting assembly to help maintain the desired environment within the receiving chamber 106 and the furnace 114. The cover or shield prevents dust and contaminants from entering while allowing control of the gaseous environment surrounding the nascent ingot 110. In some cases, instead of using a shield, a controlled environment (e.g., a vacuum) may be established within the receiving chamber 106, the furnace 114, the reel housing (e.g., reel housing 228 of FIG. 2), and the cable pulley assembly (e.g., cable pulley assembly 230 of FIG. 2).

[0057] The seed enhancement assembly 102 includes a dynamic counterweight system comprising a controller 115, one or more sensors 117A to 117H, and a dynamic counterweight assembly 121. Although not typically visible in the view depicted in Figure 1, the dynamic counterweight assembly 121 is depicted as a dashed line for illustrative purposes. The dynamic counterweight assembly 121 may include a counterweight actuator that drives a movable counterweight. The controller 115 may be positioned in any suitable location and is depicted as separate from the seed enhancement assembly 102 for illustrative purposes. In some cases, the controller 115 is positioned on the seed enhancement assembly 102. In other cases, the controller 115 is implemented by components positioned at different locations. The controller 115 may communicate with the dynamic counterweight assembly 121 and one or more sensors 117A to 117H via wired or wireless connections, which are not depicted for illustrative purposes.

[0058] During the growth process, while the seed lift assembly 102 is rotating, the controller 115 receives sensor data from one or more sensors 117A to 117H and generates a control signal that is transmitted to one of the dynamic counterweight assemblies 121. When the control signal is received by the counterweight driver of the dynamic counterweight assembly 121, the counterweight driver induces movement of the movable counterweight to help maintain the center of mass of the seed lift assembly 102 along the axis of rotation 118 (e.g., to reduce any existing deviation of the center of mass from the axis of rotation 118, or to prevent future deviation of the center of mass from the axis of rotation 118).

[0059] One or more sensors 117A to 117H may include any suitable sensor, such as those described herein. The sensors 117A to 117H depicted in Figure 1 are examples of specific useful locations for placing a sensor, but the sensor may be placed in any suitable location. A dynamic counterweight system may utilize one or more sensors 117A to 117H and / or any combination of other sensors. Sensor 117A may be an accelerometer coupled to the base plate of the seed lift assembly 102 to measure the acceleration of the seed lift assembly 102. Sensor 117B may be a proximity sensor coupled to or positioned adjacent to the rotary motor 113 to measure the rotational position of the seed lift assembly 102. For example, sensor 117B may include a magnetic source coupled to the base plate of the seed lift assembly 102, and a magnetic sensor (e.g., a reed sensor) coupled to the rotary motor 113 to indicate when the seed lift assembly 102 has rotated to a known rotational position. Sensor 117C may be a visual inspection camera positioned (e.g., at a location spaced apart from other components of the crystal growth system 100) and oriented to visually capture the seed lift assembly 102 and / or the receiving chamber 106. In some cases, sensor 117C may be positioned within the receiving chamber 106 or furnace 114 to visually capture the cable 104, seed crystal 108, and / or nascent ingot 110. Sensor 117D may be an accelerometer coupled to the leveling adapter plate 109 to measure the movement of the seed lift assembly 102 via the leveling adapter plate 109. When the seed lift assembly 102 moves, especially in the event of a misalignment between the CoM and the rotation axis 118, the leveling adapter plate 109 will move accordingly. Sensor 117E can be a load cell positioned at one of the leveling adapter pins 111 to measure the force exerted on the leveling adapter pin 111 by the leveling adapter plate 109 and the seed lift assembly 102. Especially in the event of an imbalance in the seed lift assembly 102 (e.g., a misalignment between the CoM and the rotation axis 118), the force measured at sensor 117E will change as the seed lift assembly 102 rotates. Sensor 117F can be a load cell positioned between the receiving chamber 106 and the isolation valve 103 to measure the force exerted on the furnace tank 114 via the receiving chamber 106. Especially in the event of an imbalance in the seed lift assembly 102, the force measured at sensor 117F will change as the seed lift assembly 102 rotates. Sensor 117G may be a rotary encoder mechanically coupled to a spool wound around cable 104 to measure the rotational position (including the number of rotations) of the spool. The rotational position of the spool can be used to effectively determine the CoM of the spool. Sensor 117H may be a strain gauge sensor supporting a pulley through which cable 104 passes before leaving the seed lifting device 102.Sensor 117H can measure the weight on cable 104 (e.g., the force applied to seed lifting device 102 by cable 104, seed crystal 108, and nascent ingot 110) from a reference frame of seed lifting device 102. While sensors 117A to 117H describe useful locations and types of sensors, any suitable type of sensor can be used at any suitable location.

[0060] Figure 2 is a front view of a seed lift assembly 202 according to a specific configuration of the present invention. The seed lift assembly 202 can be any suitable seed lift assembly, such as the seed lift assembly 102 of Figure 1. The seed lift assembly 202 may include a base plate 224 on which various components can be mounted. Cables can exit from a cable port 220 on the underside of the base plate 224.

[0061] The seed lift assembly 202 may include a spool positioned within a spool housing 228. A cable can be wound around the spool, allowing the spool to control the lowering and raising of the cable via rotation. The cable can unwind from the spool and pass upwards and around a pulley within a cable pulley assembly 230 before passing downwards back and exiting the cable terminal 220. The pulley within the cable pulley assembly 230 facilitates maintaining the cable at the center of the cable terminal 220.

[0062] The rotation of the reel can be controlled by a reel motor 232. The reel motor 232 can drive a gearbox 222, which in turn drives a reel spindle, which drives the rotation of the reel. For example, the reel spindle is rotatably fixed to the reel such that rotation of the reel spindle induces a corresponding rotation of the reel.

[0063] An electronic housing 234 may be positioned on the base plate 224 to house electronics used for controlling and monitoring components of the seed lift assembly 202, such as a controller for a dynamic counterweight system (e.g., controller 115 of FIG. 1). As described herein, it may be useful to maintain the center of gravity of the seed lift assembly 202 at the center of the cable port 220. Therefore, since heavy equipment (e.g., the reel motor 232, the reel gearbox 222, and part of the reel housing 228) is present on one side of the base plate 224, one or more static counterweights 226 may be positioned on the opposite side of the base plate 224.

[0064] Figure 3 is a partial cross-sectional view projection of the front portion of a seed enhancement assembly 302 according to a specific embodiment of the present invention. The seed enhancement assembly 302 can be any suitable seed enhancement assembly, such as the seed enhancement assembly 102 of Figure 1. As depicted in Figure 3, some components, such as the reel housing, are not shown for illustrative purposes.

[0065] The reel 338 is driven by the reel spindle 340, which in turn is driven by the reel gearbox 322, which is in turn driven by the reel motor 332. As the reel spindle 340 rotates to rotate the reel 338, the reel spindle also rotates a reel sprocket 336. The reel sprocket mechanically couples the reel to the limit switch assembly, causing the reel 338 to translate axially along the reel spindle 340, inducing a contact surface of the limit switch assembly to move toward a corresponding limit switch.

[0066] A cable 304 is depicted exiting one of the grooves of the spool 338 and entering the cable pulley assembly 330 before being guided downward and exiting the cable terminal 320.

[0067] Additionally, the seed lifting device 302 of Figure 3 includes a base plate 324 having a first static counterweight 326 and a second static counterweight 342. The first and second static counterweights 326 and 342 can serve as a fixed counterbalance among the fixing components of the seed lifting device 302. When the center of gravity of the reel 338 moves along a first direction (e.g., from right to left as depicted in Figure 3), a movable counterweight of the dynamic counterweight assembly 344 can be appropriately driven (e.g., by a counterweight driver, such as a motor 352) (e.g., in the opposite direction, such as from left to right as depicted in Figure 3) to counterbalance the reel 338.

[0068] Figure 4 is a partial cross-sectional rear view of a seed booster assembly 402 illustrating a specific configuration of the dynamic counterweight assembly 444 according to the present invention. The seed booster assembly 402 can be any suitable seed booster assembly, such as the seed booster assembly 102 of Figure 1. For illustrative purposes, the coverings of the electronic device housing 434 and the housing of the dynamic counterweight assembly 444 are not depicted.

[0069] The electronic assembly 434 may include electronic devices 450 for controlling and / or monitoring the seed enhancement device 402. In some cases, these electronic devices 450 may include a controller (e.g., controller 115 of FIG. 1) or a portion of a controller for generating control signals to control the dynamic counterweight assembly 444. In some cases, the dynamic counterweight assembly 444 may be positioned below the electronic assembly 434. The dynamic counterweight assembly 444 may be directly coupled to the base plate 424, but not always. However, it is desirable to keep the center of mass of the counterweight 446 closer to the base plate 424 rather than further away from it.

[0070] The dynamic counterweight assembly 444 may include a movable counterweight 446 driven by a lead screw 448. The counterweight 446 may be driven by a counterweight actuator (such as a motor 452) to move axially (e.g., axially along one of the axes of the lead screw 448). The counterweight 446 is slidably mounted within a channel 492. As disclosed in further detail herein, sensor data received by a controller may be processed to generate a control signal that can be used to control the motor 452 to cause rotation of the lead screw 448, thereby inducing axial movement of the counterweight 446.

[0071] The limit switch assembly 419 is depicted having a sprocket 468 driven by a linkage 421 (e.g., a chain) coupled to a sprocket on the reel via a gearbox. Thus, as the reel rotates, the sprocket 468 rotates thereby, causing a contact surface 423 to move toward (or away from) a limit switch.

[0072] Figure 5 is a partial cross-sectional, enlarged view of a dynamic counterweight assembly 544 according to a specific configuration of the present invention. The dynamic counterweight assembly 544 can be any suitable counterweight assembly, such as the dynamic counterweight assembly 444 in Figure 4.

[0073] The dynamic counterweight assembly 544 may include a counterweight 546 positioned (e.g., slidably positioned) within a channel 592 of the housing of the dynamic counterweight assembly 544. Although the use of a channel 592 is depicted in Figure 5, other techniques may be used to limit undesired movement (e.g., non-axial movement) of the counterweight 546, such as stabilizer bars, brackets, and the like.

[0074] Channel 592 may be formed by the various walls of the housing of the counterweight assembly 544. In some cases, at least one wall (e.g., the rear wall, or the wall coplanar with and facing away from the page in FIG. 5) may contain a crack or opening, such as an opening between an upper wall portion 554 and a lower wall portion 556. If desired, this cracked wall may facilitate access to the counterweight 546.

[0075] Additionally, this slit wall allows end stops 562, 564 to couple to the counterweight 546 and extend beyond the upper wall portion 554 and the lower wall portion 556. Each end stop 562, 564 may include an adjustable stop coupled to one of the counterweights 546 via a set of blocks. Each end stop 562, 564 may engage a respective limit switch 558, 560 at the opposite end of the adjacent channel 592. In some cases, the limit switches 558, 560 may be located elsewhere, such as within the channel 592, in which case the limit switches 558, 560 may be engaged by the counterweight 546 itself. However, by using the end stops 562, 564 and limit switches 558, 560 depicted in FIG5, the travel range of the counterweight 546 can be controlled by adjusting the position of the desired end stops 562, 564 (e.g., by adjusting the adjustable stops within the assembly and / or adjusting the blocks on the counterweight 546). Although depicted in FIG5 as having limit switches 558, 560 and end stops 562, 564, in some cases, a dynamic counterweight assembly 544 can be implemented without any limit switches 558, 560 and end stops 562, 564.

[0076] To facilitate smooth sliding motion, the counterweight 546 may include one or more wheels 566. The wheels 566 may engage with various walls of the channel 592, such as the upper wall portion 554 and the lower wall portion 556. In some cases, other friction-reducing techniques may be used in addition to or in place of the wheels 566.

[0077] Motor 552 can be coupled to lead screw 568 via a coupling member 553 (e.g., an axial shaft coupling member).

[0078] Figure 6 is a graphical projection of the front side of a counterweight 646 of a dynamic counterweight assembly according to a specific configuration of the present invention. The counterweight 646 can be any suitable counterweight, such as the counterweight 446 in Figure 4. For illustrative purposes, the counterweight 446 is depicted as transparent.

[0079] The counterweight 646 can have any suitable shape, but in some cases a rectangular shape is used. The counterweight 646 may include several wheels 666A, 666B, 666C, 666D, 666E, 666F, 666G, and 666H. Any number can be used, but in some cases eight wheels are used. Wheels 666A and 666B can be positioned on a top rear side at opposite ends of the counterweight 646. Wheels 666A and 666B can engage the upper wall portion of the channel (e.g., upper wall portion 554 in Figure 5). Corresponding wheels 666E and 666F can be positioned on a bottom rear side at opposite ends of the counterweight 646. Wheels 666E and 666F can engage the lower wall portion of the channel (e.g., lower wall portion 556 in Figure 5). Wheels 666C and 666D can be positioned on the top and bottom sides of the counterweight 646, respectively, to engage with the corresponding surfaces in the channel.

[0080] To drive the counterweight 646, a lead screw 648 interacts with a nut 674. The nut 674 is rotatably fixed to the counterweight 646. A cavity 672 within the counterweight extends through some or all of the counterweight 646 and has a diameter larger than the diameter of the lead screw 648, thus allowing the counterweight 646 to move upward (e.g., proximal) along the lead screw 648. As the lead screw 648 is rotated by a counterweight actuator (e.g., motor 552 of FIG. 5), the nut 674 remains rotatably fixed to the counterweight 646, which in turn remains substantially rotatably fixed relative to the channel. Therefore, rotation of the lead screw 648 causes the nut 674 to move upward (e.g., proximal) or downward (e.g., distal) along the lead screw 648.

[0081] Figure 7 is a schematic top view of a seed lifting assembly 702 according to a specific embodiment of the present invention, wherein the reel 738 is in a first reel position and the movable counterweight 746 is in a first counterweight position. The seed lifting assembly 702 can be any suitable seed lifting assembly, such as the seed lifting assembly 102 of Figure 1. In some cases, the first reel position and the first counterweight position may correspond to an initial reel position and an initial counterweight position at the beginning of a crystal growth process (e.g., when the cable begins to rise from the melt). At this initial position, the entire seed lifting assembly 702 may be balanced, but not always. A cable 704 may enter the seed lifting assembly 702 via a cable port 720.

[0082] One of the transverse center lines 788 (or transverse planes) of the seed lift assembly 702 can be defined as a line (or plane) extending through the center of the cable port 720 (e.g., through the centroid 778 of the seed lift assembly 702) and perpendicular to the axis of the reel spindle 740. The transverse center line 788 (or transverse plane) can divide the seed lift assembly 702 into a "left" side and a "right" side, as depicted in Figure 7.

[0083] A longitudinal centerline 790 (or longitudinal plane) of the seed lift assembly 702 can be defined as a line (or plane) extending through the center of the cable port 720 (e.g., through the centroid 778 of the seed lift assembly 702) and parallel to the axis of the reel spindle 740. The longitudinal centerline 790 (or longitudinal plane) can divide the seed lift assembly 702 into a "top" side and a "bottom" side, as depicted in Figure 7.

[0084] In the first reel position, the reel 738 is positioned proximal to the reel spindle 740. The reel 738 contains several turns of wound cable 786 within its groove 784. The reel's center of mass 782 is depicted and rests to the left of the transverse centerline 788 and at the bottom of the longitudinal centerline 790.

[0085] In the first counterweight position, the counterweight 746 is positioned proximal to the lead screw 748. In some cases, in the first counterweight position, a first end stop 764 may engage a first limit switch 760, but this is not always necessary. The counterweight center of mass 780 is depicted and rests to the right of the transverse centerline 788 or on one side of the transverse centerline 788 opposite to the reel center of mass 782. The counterweight center of mass 780 rests at the top of the longitudinal centerline 790 or on one side of the longitudinal centerline 790 opposite to the reel center of mass 782. For illustrative purposes, the counterweight center of mass 780 is depicted on one side of the transverse centerline 788 opposite to the reel center of mass 782, but this is not always necessary. In some cases, the counterweight 746 may be positioned so that it does not intersect the transverse centerline 788 during use.

[0086] As the reel 738 rotates to wind up the additional cable 704, it will move distally along the reel spindle 740 (e.g., from left to right as seen in Figure 7). The reel's center of mass 782 will move toward the transverse centerline 788, and in some cases, the movement will pass through the transverse centerline 788. The axial movement of the reel 738 during rotation can cause a deviation between the center of mass 778 of the seed lift assembly 702 and the axis of rotation 704. This deviation can be detected by a controller (e.g., controller 115 of Figure 1) via sensor data from one or more sensors (e.g., sensors 117A to 117H). The controller can then generate a control signal to drive a motor 752, which in turn rotates a lead screw 748 to drive a counterweight 746 to move axially in the opposite direction to the reel 738 (e.g., the counterweight 746 may move from right to left, as seen in Figure 7). The counterweight center of gravity 780 will move toward the transverse centerline 788, and in some cases, the movement will pass through the transverse centerline 788. In some cases, when the reel center of gravity 782 reaches the transverse centerline 788, the counterweight center of gravity 780 will also reach the transverse centerline 788, but this is not always the case. The movement of the counterweight 746 helps to reduce deviation and further prevent future deviations from occurring.

[0087] Therefore, when the reel center of mass 782 moves relative to the center of the cable port 720, the counterweight center of mass 780 can be driven in a corresponding opposite direction based on sensor data to maintain the center of mass 778 of the seed lift assembly 702 in the same position (e.g., at or above the center of the cable port 720 and / or along one of the rotation axes of the seed lift assembly 702). Additionally, the counterweight center of mass 780 can be driven based on sensor data in a manner suitable for taking into account other sources of deviation of the center of mass 778.

[0088] Figure 8 is a schematic top view of a seed lifting assembly 802 according to a specific configuration of the present invention, wherein the reel 838 is in a second reel position and the movable counterweight 846 is in a second counterweight position. The seed lifting assembly 802 can be any suitable seed lifting assembly, such as the seed lifting assembly 102 of Figure 1. In some cases, the second reel position and the second counterweight position may correspond to an end reel position and an end counterweight position at the end of a crystal growth process (e.g., after the cable has been raised to its highest set point), but this is not always the case. A cable 804 may enter the seed lifting assembly 802 via a cable port 820.

[0089] One of the transverse center lines 888 (or transverse planes) of the seed lift assembly 802 can be defined as a line (or plane) extending through the center of the cable port 820 (e.g., through the centroid 878 of the seed lift assembly 802) and perpendicular to the axis of the reel spindle 840. The transverse center line 888 (or transverse plane) can divide the seed lift assembly 802 into a "left" side and a "right" side, as depicted in Figure 8.

[0090] A longitudinal centerline 890 (or longitudinal plane) of the seed lift assembly 802 can be defined as a line (or plane) extending through the center of the cable port 820 (e.g., through the centroid 878 of the seed lift assembly 802) and parallel to the axis of the reel spindle 840. The longitudinal centerline 890 (or longitudinal plane) can divide the seed lift assembly 802 into a "top" side and a "bottom" side, as depicted in Figure 8.

[0091] In the second reel position, the reel 838 is positioned at the distal end along the reel spindle 840. The reel 838 contains a plurality of turns of wound cable 886 in its groove 884. The reel's center of mass 882 is depicted and rests to the right of the transverse centerline 888 and at the bottom of the longitudinal centerline 890.

[0092] In the second counterweight position, the counterweight 846 is positioned distally along the lead screw 848. In some cases, in the second counterweight position, a second end stop 862 may engage a second limit switch 858. The counterweight center of mass 880 is depicted and rests to the left of the transverse centerline 888 or on one side of the transverse centerline 888 opposite to the reel center of mass 882. The counterweight center of mass 880 rests at the top of the longitudinal centerline 890 or on one side of the longitudinal centerline 890 opposite to the reel center of mass 882. For illustrative purposes, the counterweight center of mass 880 is depicted on one side of the transverse centerline 888 opposite to the reel center of mass 882, but this is not always necessary. In some cases, the counterweight 846 may be positioned so that it does not intersect the transverse centerline 888 during use.

[0093] As the spool 838 rotates to unwind the wound cable 886, it will move proximally along the spool spindle 840 (e.g., from right to left as seen in Figure 8). The spool's center of mass 882 will move toward the transverse centerline 888, and in some cases, the movement will pass through the transverse centerline 888. The axial movement of the spool 838 during rotation can cause a deviation between the center of mass 878 of the seed lift assembly 802 and the axis of rotation 804. This deviation can be detected by a controller (e.g., controller 115 of Figure 1) via sensor data from one or more sensors (e.g., sensors 117A to 117H). The controller can then generate a control signal to drive a motor 852, which in turn rotates a lead screw 848 to drive a counterweight 846 to move axially in the opposite direction to the spool 838 (e.g., the counterweight 846 may move from left to right, as seen in Figure 8). The counterweight center of mass 880 will move toward the transverse centerline 888, and in some cases, the movement will pass through the transverse centerline 888. In some cases, when the reel center of mass 882 reaches the transverse centerline 888, the counterweight center of mass 880 will also reach the transverse centerline 888, but this is not always the case. The movement of the counterweight 846 helps to reduce deviation and further prevent future deviations from occurring.

[0094] Therefore, when the reel center of mass 882 moves relative to the center of the cable port 820, the counterweight center of mass 880 can be driven in a corresponding opposite direction based on sensor data to maintain the center of mass 878 of the seed lift assembly 802 in the same position (e.g., at or above the center of the cable port 820 and / or along one of the rotation axes of the seed lift assembly 802). Additionally, the counterweight center of mass 880 can be driven based on sensor data in a manner suitable for taking into account other sources of deviation of the center of mass 878.

[0095] Figure 9 is a schematic rear view of a dynamic counterweight assembly 944 of a specific type according to the present invention. The dynamic counterweight assembly 944 is a counterweight assembly that can be used as an alternative to any suitable seed enhancement assembly (such as the seed enhancement assembly 102 of Figure 1).

[0096] The dynamic counterweight assembly 944 may be similar to other dynamic counterweight assemblies as disclosed herein, but the counterweight 946 may be coupled to a bracket 947 traveling on a linear track 996. The counterweight 946, bracket 947, and track 996 may serve as counterweights for components on opposite sides of the seed lift assembly, wherein the counterweight 946 and bracket 947 are movable to compensate for spool movement and otherwise correct for deviations in the center of mass of the seed lift assembly.

[0097] The lead screw 948 can be coupled to the bracket 947 such that rotation of the lead screw 948 by a counterweight actuator (e.g., motor 552 of FIG. 5) will cause the bracket 947 to move axially along the track 996. Rollers 999 of the bracket 947 can be fitted within a guide rail 998 of the track 996 to maintain the bracket 947 sliding along the track 996 with low friction. In some cases, the rollers 999 can be in the form of wheels or bearings. In some cases, the linear guide rail 996 can be an extrusion having a "T"-shaped guide rail 998.

[0098] A counterweight 946 may be coupled to a bracket 947. In some cases, the counterweight 946 may be coupled to the bracket 947 in only a single position, but this is not always necessary. In some cases, the counterweight 946 may be coupled to the bracket 947 in multiple axial positions (e.g., from left to right as seen in Figure 9). In such cases, the counterweight 946 may be axially adjusted relative to the bracket 947 to fine-tune the combined center of gravity of the counterweight 946 and the bracket 947, such as the position relative to the center of gravity of the reel.

[0099] In some cases, rail 996 can be replaced by two or more rails. In some cases, the axial movement of bracket 947 can be driven by an alternative linear actuator instead of a lead screw 948.

[0100] Figure 10 is a schematic diagram of a crystal growth system 1000 with a dynamic counterweight system according to a specific configuration of the present invention. The crystal growth system 1000 can be any suitable crystal growth system, such as the crystal growth system 100 of Figure 1. The crystal growth system 1000 may include a seed lifting assembly 1002 rotatably coupled to a receiving chamber 1006 via a leveling adapter 1005. The receiving chamber 1006 may be coupled to a furnace bath 1014.

[0101] The dynamic counterweight system may include: a dynamic counterweight assembly 1044, which includes a counterweight 1046 driven by a counterweight driver 1052; a controller 1015; and one or more sensors 1017A to 1017D. The controller 1015 is depicted as being housed within a seed lift assembly 1002, but not always. The controller 1015 is communicatively coupled to the counterweight driver 1052 and each of the one or more sensors 1017A to 1017D. The controller 1015 receives sensor data from one or more sensors 1017A to 1017D and processes the sensor data to generate a control signal. The control signal is then supplied to the counterweight driver 1052 to drive the counterweight 1046 to dynamically bring the seed lift assembly 1002 toward balance (e.g., the center of mass of the seed lift assembly 1002 does not deviate from or substantially deviates from the axis of rotation of the seed lift assembly 1002) or to maintain the balance of the seed lift assembly 1002.

[0102] Sensor 1017A may be an accelerometer, such as one coupled to the seed lift assembly 1002 at the base plate of the seed lift assembly 1002, to measure the acceleration of the seed lift assembly 1002. Sensor 1017B may be an accelerometer or load sensor coupled to or otherwise positioned at the leveling adapter 1005 to measure the movement of the seed lift assembly 1002 via the movement of the leveling adapter plate of the leveling adapter or via the force applied by one or more leveling adapter pins of the leveling adapter. When the seed lift assembly 1002 moves, especially when it is unbalanced, the leveling adapter plate will move accordingly, and the amount of force applied by each leveling adapter pin will vary with the rotational position of the seed lift assembly 1002. Sensor 1017C may be an accelerometer positioned on the receiving chamber 1006 to measure the movement of the receiving chamber. When the seed lift assembly 1002 moves, especially when it is unbalanced, the receiving chamber 1006 will move accordingly. Sensor 1017D may be a load cell positioned between the receiving chamber 1006 and the furnace trough 1014 (e.g., between the receiving chamber 1006 and an isolation valve coupling the receiving chamber 1006 to the furnace trough 1014) to measure the force applied to the furnace trough 1014 via the receiving chamber 1006. Especially when the seed lift assembly 1002 is unbalanced, the force measured at sensor 1017D will change as the seed lift assembly 1002 rotates. Sensors 1017B to 1017D can be considered to be fixedly positioned relative to the receiving chamber. For example, if each of sensors 1017B to 1017D is an accelerometer, it will be able to detect the acceleration of the receiving chamber.

[0103] Figure 11 is a flowchart depicting one of the procedures 1100 for dynamically balancing a seed enhancement according to a specific state of the present invention. Procedure 1100 can be executed by any suitable crystal growth system (such as the crystal growth system 100 of Figure 1).

[0104] In some cases, program 1100 may be initiated at block 1102 by installing a dynamic counterweight system onto an existing crystal growth system. Therefore, at block 1102, an existing crystal growth system can be modified to perform dynamic counterweight balancing.

[0105] In block 1104, a seed crystal is lowered into a melt. The seed crystal is attached to a cable or similar flexible support that is itself supported by a seed crystal lifting assembly. The seed crystal can be lowered to contact the melt and seed crystal formation can begin.

[0106] In block 1106, the seed crystal lifting assembly is rotated, and the seed crystal is raised. Rotating the seed crystal lifting assembly includes inducing the seed crystal to rotate relative to the melt. In some cases, rotating the seed crystal lifting assembly occurs when one of the crucibles containing the melt rotates in the opposite direction. Raising the seed crystal may include winding a cable onto a spool. Winding the cable onto the spool includes axially displacing the spool, and thus axially displacing the center of mass of the spool relative to the center of mass of the seed crystal lifting assembly.

[0107] In block 1108, a movable counterweight is dynamically adjusted. This dynamic adjustment of the movable counterweight in block 1108 occurs simultaneously with the rotation of the seed lift assembly in block 1106. The dynamic adjustment of the movable counterweight in block 1108 may include detecting the movement of the seed lift assembly in block 1110. The movement of the seed lift assembly detected in block 1110 may be detected by one or more sensors. In some cases, the detection of the movement of the seed lift involves detecting changes in acceleration or force of one or more components of the crystal growth system, which have been attributed to the rotation of the seed lift assembly when it is not fully balanced.

[0108] After block 1110 detects movement of the seed lift assembly, a control signal can be generated in block 1112. The control signal can be generated based on sensor data received from one or more sensors in block 1110. The control signal can be generated such that it tends the seed lift assembly towards balance (e.g., the center of mass of the seed lift assembly does not deviate from or substantially deviates from the axis of rotation of the seed lift assembly) or maintains the balance of the seed lift assembly. Therefore, the control signal can be generated such that a movable counterweight counteracts a deviation of the center of mass of the seed lift assembly from one of its axes of rotation (e.g., a sensed deviation or a predicted deviation).

[0109] In block 1114, a control signal can be used to accordingly drive a movable counterweight (e.g., to counteract deviation). Driving the movable counterweight in block 1114 may include actuating a counterweight driver to cause the movable counterweight to move toward a desired position. In some cases, driving the movable counterweight in block 1114 may include moving the movable counterweight at a speed provided in the control signal. In some cases, driving the movable counterweight in block 1114 may include moving the movable counterweight for a duration equal to the duration of the control signal or one of the durations provided in the control signal.

[0110] Due to the dynamic adjustment of the movable counterweight in block 1108, the deviation of the center of mass of the seed lifting assembly from its axis of rotation can be corrected and / or avoided.

[0111] Depending on the desired time, ingot length, amount of material used, or other criteria, procedure 1100 can end at block 1116.

[0112] Although procedure 1100 is described with reference to specific blocks in a specific order, any suitable order and additional and / or fewer blocks may be used. For example, in some cases, procedure 1100 further includes engaging a limit switch as part of lowering the seed crystal to the melt in block 1104 or after lowering the seed crystal to the melt in block 1104.

[0113] The specific embodiments of the present invention described above (including the illustrated embodiments) are presented for illustrative and descriptive purposes only and are not intended to be exhaustive or limited to the precise forms disclosed. Those skilled in the art will understand that many modifications, adaptations, and uses are possible. Many changes can be made to the disclosed embodiments based on the contents herein without departing from the spirit or scope of the invention. Therefore, the breadth and scope of the invention should not be limited by any of the above embodiments.

[0114] Although the invention has been illustrated and described with respect to one or more embodiments, equivalent changes and modifications will be conceived or known by those skilled in the art upon reading and understanding this specification and the accompanying drawings. Furthermore, while a particular feature of the invention may be disclosed only in one of several embodiments, this feature may be combined with one or more other features of other embodiments as may be desired and advantageous to any given or particular application.

[0115] The terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the invention. As used herein, the singular forms "a," "an," and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise. Furthermore, with respect to the use of the terms "including / includes," "having / has," "with," or variations thereof in the [implementation] and / or the scope of the invention claims, these terms are intended to be inclusive in a manner similar to the term "including."

[0116] As used below, any reference to a series of instances should be understood separately as a reference to each of those instances (e.g., "Instances 1 through 4" should be understood as "Instances 1, 2, 3, or 4").

[0117] Example 1 is a dynamic counterweight system for crystal growth, comprising: a counterweight assembly coupled to a seed crystal lifting assembly, the seed crystal lifting assembly being rotatably coupled to a receiving chamber about a rotation axis and supporting a crystal within the receiving chamber; the counterweight assembly including: a movable counterweight axially movable along a counterweight axis between a first position and a second position; and a counterweight actuator operably coupled to the movable counterweight to induce movement of the movable counterweight along the counterweight axis in response to a control signal. The system includes one or more sensors positioned to detect movement of the seed crystal lifting assembly; and a controller operatively coupled to the one or more sensors and the counterweight driver, the controller being configured to: receive one or more sensor signals from the one or more sensors; generate the control signal based on the received one or more sensor signals; and transmit the control signal to the counterweight driver, wherein the control signal, when received by the counterweight driver, induces movement of the movable counterweight to counteract a deviation of the center of mass of the seed crystal lifting assembly.

[0118] Example 2 is a dynamic counterweight system as in Example 1 (some of the examples), wherein the one or more sensors include a load element positioned to couple the seed lift assembly to the receiving chamber to detect the force applied to the receiving chamber by the seed lift assembly as the seed lift assembly rotates about the rotation axis.

[0119] Example 3 is a dynamic counterweight system like (some) Examples 1 or 2, wherein the one or more sensors include a load element positioned between the receiving chamber and a furnace trough to detect the force applied by the receiving chamber to the furnace trough when the seed lifting assembly rotates about the rotation axis.

[0120] Example 4 is a dynamic counterweight system like (a plurality of) Examples 1 to 3, wherein the one or more sensors include an accelerometer positioned on the seed lift assembly to detect the acceleration of the seed lift assembly during rotation of the seed lift assembly about the rotation axis.

[0121] Example 5 is a dynamic counterweight system like (a plurality of) Examples 1 to 4, wherein the one or more sensors include an accelerometer fixedly positioned relative to the receiving chamber to detect the acceleration of the receiving chamber during the rotation of the seed lifting assembly about the rotation axis.

[0122] Example 6 is a dynamic counterweight system like (a plurality of) Examples 1 to 5, wherein the one or more sensors include a rotational position sensor for detecting the rotational position of the seed lift assembly relative to one of the receiving chambers.

[0123] Example 7 is a dynamic counterweight system like (a plurality of) Examples 1 to 6, wherein the counterweight driver includes a motor coupled to a lead screw to rotate the lead screw in response to the control signal, wherein the movable counterweight is coupled to the lead screw, and wherein rotation of the lead screw induces the movable counterweight to slide along the counterweight axis.

[0124] Example 8 is a dynamic counterweight system like (a plurality of) Examples 1 to 7, wherein the seed lifting assembly includes a reel having a spiral collection groove extending along a length of the reel, wherein the reel is rotatable about a reel axis to wind a cable into the collection groove as the reel moves longitudinally along the reel axis, wherein the cable supports the seed crystal in the receiving chamber, and wherein the counterweight axis is parallel to the reel axis.

[0125] Example 9 is a dynamic counterweight system like (some) Example 8, wherein at least some of the deviations of the center of mass of the seed lifting assembly are caused by the longitudinal movement of the reel along a first direction during a crystal growth operation, and wherein the control signal, when received by the counterweight driver, induces the movable counterweight to move along a second direction opposite to the first direction to counteract at least some of the deviations of the center of mass of the seed lifting assembly.

[0126] Example 10 describes a crystal growth system comprising: a furnace bath having a crucible for receiving a melt; a receiving chamber having a lower end coupled to the furnace bath via an isolation valve and a top end coupled to a leveling adapter via a plurality of leveling adapter posts; a crystal suspended in the receiving chamber by a cable along a cable centerline; a seed lifting assembly rotatably coupled to the receiving chamber via the leveling adapter about a rotation axis and having an assembly centroid along the cable centerline, the seed lifting assembly supporting the cable in the growth chamber, the seed lifting assembly having a reel for raising the cable, the reel having a reel centroid that moves relative to the cable centerline when the cable is raised; and a dynamic counterweight system comprising: a counterweight assembly coupled to the seed lifting assembly, the counterweight assembly including: a movable counterweight movable along a counterweight axis... Axial movement between a first position and a second position; and a counterweight actuator operatively coupled to the movable counterweight to induce movement of the movable counterweight along the counterweight axis in response to a control signal; one or more sensors positioned to detect movement of the seed lift assembly; and a controller operatively coupled to the one or more sensors and the counterweight actuator, the controller being configured to: receive one or more sensor signals from the one or more sensors; generate the control signal based on the received one or more sensor signals; and transmit the control signal to the counterweight actuator, wherein the control signal, upon being received by the counterweight actuator, induces movement of the movable counterweight to counteract the deviation of the assembly's center of mass from the cable's centerline, and wherein at least some of such deviations of the assembly's center of mass from the cable's centerline are caused by the movement of the reel's center of mass during cable lifting.

[0127] Example 11 is a crystal growth system like (some) Example 10, wherein the one or more sensors include a load element located at one of the leveling transition posts to detect the force applied to the receiving chamber by the seed lift assembly as the seed lift assembly rotates about the rotation axis.

[0128] Example 12 is a crystal growth system like (some) Examples 10 or 11, wherein the one or more sensors include a load cell located between the receiving chamber and the isolation valve to detect the force applied to the furnace by the receiving chamber when the seed lift assembly rotates about the rotation axis.

[0129] Example 13 is a crystal growth system like (a plurality of) Examples 10 to 12, wherein the one or more sensors include an accelerometer positioned on the seed lift assembly to detect the acceleration of the seed lift assembly during rotation of the seed lift assembly about the rotation axis.

[0130] Example 14 is a crystal growth system like (a few) Examples 10 to 13, wherein the one or more sensors include an accelerometer located at the leveling adapter or the isolation valve to detect the acceleration of the receiving chamber during the rotation of the seed lift assembly about the rotation axis.

[0131] Example 15 is a crystal growth system like (a few) Examples 10 to 14, wherein the one or more sensors include a rotational position sensor for detecting the rotational position of the seed lift assembly relative to one of the leveling adapters.

[0132] Example 16 is a crystal growth system like (a plurality of) Examples 10 to 15, wherein the counterweight actuator includes a motor coupled to a lead screw to rotate the lead screw in response to the control signal, wherein the movable counterweight is coupled to the lead screw, and wherein rotation of the lead screw induces the movable counterweight to slide along the counterweight axis.

[0133] Example 17 is a crystal growth system like (a plurality of) Examples 10 to 16, further comprising a limit switch assembly mechanically coupled to the reel to limit the reel's movement beyond one or more limit positions, wherein the limit switch assembly is not driven by the counterweight driver.

[0134] Example 18 is a method for growing a crystal, comprising: lowering a crystal to a melt by means of a cable supported by a seed lift assembly; simultaneously rotating the seed lift assembly about a rotation axis and raising the cable, wherein raising the cable includes raising the cable by means of movement of an assembly of the seed lift assembly, wherein the movement of the assembly causes a displacement of the center of mass of the assembly relative to the rotation axis; and dynamically counteracting the deviation of the center of mass of the seed lift assembly from the rotation axis, wherein dynamically counteracting the deviation includes: via One or more sensors detect the movement of the seed lift assembly during rotation of the seed lift assembly; generate a control signal based on the detected movement; transmit the control signal to a counterweight driver operatively coupled to a movable counterweight axially movable between a first position and a second position along a counterweight axis; and drive the movable counterweight by the counterweight driver in response to receiving the transmitted control signal, wherein driving the movable counterweight includes inducing the movable counterweight to move by an amount sufficient to counteract the deviation.

[0135] Example 19 is a method as described in (a few) Examples 18, wherein the seed lift assembly is coupled to a receiving chamber by a leveling adapter, the leveling adapter being coupled to the receiving chamber by a plurality of leveling adapter posts; wherein the melt is contained in a furnace bath coupled to the receiving chamber by an isolation valve; and wherein detecting the movement of the seed lift assembly during rotation of the seed lift assembly via one or more sensors includes: i) detecting the force applied by the seed lift assembly to the melt via a load cell located at one of the leveling adapter posts of the leveling adapter. ii) the force applied from the receiving chamber to the furnace trough by a load cell located between the receiving chamber and the isolation valve; iii) the acceleration of the seed lifting assembly detected by an accelerometer located on the seed lifting assembly; iv) the acceleration of the receiving chamber detected by an accelerometer located at the leveling adapter; v) the acceleration of the receiving chamber detected by an accelerometer located at the isolation valve; vi) the rotational position of the seed lifting assembly relative to the leveling adapter; or vii) any combination of i to vi.

[0136] Example 20 is a method as in Examples 18 or 19, wherein the counterweight drive includes a motor coupled to a lead screw to rotate the lead screw in response to the control signal, wherein the movable counterweight is coupled to the lead screw, and wherein rotation of the lead screw induces the movable counterweight to slide along the counterweight axis.

[0137] 100: Crystal Growth System 102: Seed enhancement assembly / seed enhancement device 103: Isolation Valve 104: Cable 105: Leveling Adapter 106: Reception Room 107: Bearing 108: Seed Crystal 109: Leveling adapter plate 110: Nascent Crystal Ingot 111: Leveling Adapter Pin 112: Melt 113: Rotary motor 114: Furnace trough / furnace 115: Controller 116: Crucible 117A to 117H: Sensors 118: Axis of rotation 121: Dynamic counterweight assembly 202: Seed Enhancement Assembly 220: Cable Terminal 222: Gearbox 224: Base Plate 226: Static counterweight 228: Reel housing 230: Cable pulley assembly 232: Reel motor 234: Electronic device casing 302: Seed enhancement assembly / seed enhancement device 304: Cable 320: Cable Terminal 322: Reel gearbox 324: Base Plate 326: First static counterweight 330: Cable pulley assembly 332: Reel motor 336: Spindle sprocket 338: Scroll 340: Scroll spindle 342: Second static counterweight 344: Dynamic counterweight assembly 352: Motor 402: Seed enhancement assembly / seed enhancement device 419: Limit switch assembly 421: Linkage assembly 423: Contact Surface 424: Base Plate 434: Electronic component housing / electronic assembly 444: Dynamic counterweight assembly 446: Counterweight 448: Lead screw 450: Electronic Components 452: Motor 468: Sprocket 492: Channel 544: Dynamic counterweight assembly 546: Counterweight 552: Motor 553: Coupling component 554: Upper wall portion 556: Lower wall portion 558: Limit Switch 560: Limit Switch 562: End stop 564: End stop 566: Wheels 568: Lead screw 592: Channel 646: Counterweight 648: Lead screw 666A to 666H: Wheels 672: Cavity 674: Nut 702: Seed Enhancement Assembly 704: Cable / Rotating Axis 720: Cable Terminal 738: Scroll 740: Scroll spindle 746: Counterweight 748: Lead screw 752: Motor 760: First limit switch 764: First end stop 778: Center of Mass 780: Counterweight center of gravity 782: Scroll centroid 784: Groove 786: Wrapped cable 788: Horizontal centerline 790: Longitudinal centerline 802: Seed Enhancement Assembly 804: Cable / Rotating Axis 820: Cable Terminal 838: Scroll 840: Scroll spindle 846: Counterweight 848: Lead screw 852: Motor 858: Second limit switch 862: Second end stop 878: Center of Mass 880: Counterweight center of gravity 882: Scroll centroid 884: Groove 886: Wrapped cable 888: Horizontal centerline 890: Longitudinal centerline 944: Dynamic counterweight assembly 946: Counterweight 947: Bracket 948: Lead screw 996: Linear Orbit 998: Guide Rail 999: Roller 1000: Crystal Growth System 1002: Seed Enhancement Assembly 1005: Leveling Adapter 1006: Reception Room 1014: Furnace trough 1015: Controller 1017A to 1017D: Sensors 1044: Dynamic counterweight assembly 1046: Counterweight 1052: Counterweight Drive 1100: Program 1102: Square 1104: Square 1106: Square 1108: Square 1110: Square 1112: Square 1114: Square 1116: Square

Claims

1. A dynamic counterweight system for crystal growth, comprising: A counterweight assembly coupled to a seed crystal lifting assembly rotatably coupled to a receiving chamber about a rotation axis and supporting a seed crystal within the receiving chamber, the counterweight assembly comprising: a movable counterweight axially movable along a counterweight axis between a first position and a second position; and a counterweight actuator operably coupled to the movable counterweight to induce movement of the movable counterweight along the counterweight axis in response to a control signal; one or more sensors positioned to detect movement of the seed crystal lifting assembly; and a controller operably coupled to the one or more sensors and the counterweight actuator, the controller being configured to: receive one or more sensor signals from the one or more sensors; The control signal is generated based on the received signals from one or more sensors; and the control signal is transmitted to the counterweight driver, wherein the control signal, when received by the counterweight driver, induces movement of the movable counterweight to counteract the deviation of the center of mass of the seed lift assembly; wherein the one or more sensors include an accelerometer positioned on the seed lift assembly to detect the acceleration of the seed lift assembly during rotation of the seed lift assembly about the rotation axis.

2. The dynamic counterweight system of claim 1, wherein the one or more sensors include a load cell positioned to couple the seed lift assembly to the receiving chamber to detect the force applied to the receiving chamber by the seed lift assembly as the seed lift assembly rotates about the rotation axis.

3. The dynamic counterweight system of claim 1, wherein the one or more sensors include a load cell positioned between the receiving chamber and a furnace trough to detect the force applied by the receiving chamber to the furnace trough as the seed lifting assembly rotates about the rotation axis.

4. The dynamic counterweight system of claim 1, wherein the one or more sensors include a rotational position sensor for detecting the rotational position of the seed lift assembly relative to one of the receiving chambers.

5. The dynamic counterweight system of claim 1, wherein the counterweight actuator includes a motor coupled to a lead screw to rotate the lead screw in response to the control signal, wherein the movable counterweight is coupled to the lead screw, and wherein rotation of the lead screw induces sliding of the movable counterweight along the counterweight axis.

6. The dynamic counterweight system of claim 1, wherein the seed crystal lifting assembly includes a reel having a spiral collection groove extending along a length of the reel, wherein the reel is rotatable about a reel axis to wind a cable into the collection groove as the reel moves longitudinally along the reel axis, wherein the cable supports the seed crystal in the receiving chamber, and wherein the counterweight axis is parallel to the reel axis.

7. The dynamic counterweight system of claim 6, wherein at least some of the deviations of the center of mass of the seed lifting assembly are caused by the longitudinal movement of the reel in a first direction during a crystal growth operation, and wherein the control signal, when received by the counterweight driver, induces the movable counterweight to move in a second direction opposite to the first direction to counteract at least some of the deviations of the center of mass of the seed lifting assembly.

8. A dynamic counterweight system for crystal growth, comprising: A counterweight assembly coupled to a seed crystal lifting assembly rotatably coupled to a receiving chamber about a rotation axis and supporting a seed crystal within the receiving chamber, the counterweight assembly comprising: a movable counterweight axially movable along a counterweight axis between a first position and a second position; and a counterweight actuator operably coupled to the movable counterweight to induce movement of the movable counterweight along the counterweight axis in response to a control signal; one or more sensors positioned to detect movement of the seed crystal lifting assembly; and a controller operably coupled to the one or more sensors and the counterweight actuator, the controller being configured to: receive one or more sensor signals from the one or more sensors; The control signal is generated based on the received signals from one or more sensors; and the control signal is transmitted to the counterweight driver, wherein the control signal, when received by the counterweight driver, induces movement of the movable counterweight to counteract a deviation of the center of mass of the seed lifting assembly; wherein the one or more sensors include an accelerometer fixedly positioned relative to the receiving chamber to detect the acceleration of the receiving chamber during rotation of the seed lifting assembly about the rotation axis.

9. A dynamic counterweight system for crystal growth, comprising: A counterweight assembly coupled to a seed crystal lifting assembly rotatably coupled to a receiving chamber about a rotation axis and supporting a seed crystal within the receiving chamber, the counterweight assembly comprising: a movable counterweight axially movable along a counterweight axis between a first position and a second position; and a counterweight actuator operably coupled to the movable counterweight to induce movement of the movable counterweight along the counterweight axis in response to a control signal; one or more sensors positioned to detect movement of the seed crystal lifting assembly; and a controller operably coupled to the one or more sensors and the counterweight actuator, the controller being configured to: receive one or more sensor signals from the one or more sensors; The control signal is generated based on the received signals from one or more sensors; and the control signal is transmitted to the counterweight driver, wherein the control signal, when received by the counterweight driver, induces movement of the movable counterweight to counteract the deviation of the center of mass of the seed lifting assembly; wherein the one or more sensors include a rotational position sensor for detecting the rotational position of the seed lifting assembly relative to one of the receiving chambers.

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