System and method for measuring mechanical wear in a crystal puller - Patents.com

Abstract

The detection system includes a load cell connected to the gear and motor of the crystal puller to measure the force on the gear in the time domain. The data is analyzed to obtain frequency domain data by Fourier transformation. The frequency domain data includes an amplitude corresponding to mechanical wear of the gear. The time domain data is compared to a threshold amplitude to determine if the gear is experiencing mechanical wear so that preventative maintenance can be performed on the motor.

Description

[Technical field]

[0001] The present disclosure relates to the production of single crystal ingots, such as silicon ingots, and more particularly to methods and systems for measuring mechanical wear in crystal puller components during production without shutting down the crystal puller. [Background technology]

[0002] The critical moving parts in the puller are responsible for the steady, controlled rotation and pulling of the crystal. Over time, and due to overloading of the puller parts, gears, bearings, pulleys and other components can experience significant wear. If not properly monitored and maintained, parts can fail, affecting the puller's primary functions.

[0003] Repairs and maintenance of these components are often difficult due to inaccessibility of the components, and downtime to visually inspect the components is costly and time consuming. For example, the pulling head of a crystal puller must be at least partially disassembled and each gear individually inspected for wear. Thus, there is a need to monitor crystal puller components and detect problems with those components without interrupting crystal puller operation, before wear affects crystal puller performance or crystal quality, or before catastrophic failure occurs.

[0004] This Background section is intended to introduce the reader to various aspects of art that may be related to various aspects of the present disclosure that are described and / or claimed below. This discussion is believed to be helpful in providing the reader with background information to better understand the various aspects of the present disclosure. As such, it should be understood that these statements are to be read in this light, and not as admissions of prior art. Summary of the Invention

[0005] One embodiment is a crystal pulling system including a crucible containing molten semiconductor material, a cable and a gear, a crystal disposed on an end of the cable during pulling of the crystal, and a motor for pulling the cable and the crystal from the melt. A load cell is connected to the gear and measures a force applied to the gear, and the control system includes a processor connected to the load cell. The processor is configured to process data received from the load cell and is configured to receive time domain data from the load cell at a measurement time during the crystal pulling process. The processor also converts the time domain data to frequency domain data in the frequency domain, the frequency domain data including a force frequency amplitude at the measurement time. The processor determines whether the force frequency amplitude exceeds a threshold value.

[0006] Another aspect is a detection system including a load cell connected to a gear to measure a force on the gear in a time domain, and a control system including a processor connected to the load cell. The control system is configured to process data received from the load cell and directs the control system to receive time domain data from the load cell during a measurement time during a crystal pulling process and convert the time domain data in a frequency domain to frequency domain data. The frequency domain data includes an amplitude at the measurement time, and the processor determines whether the amplitude exceeds a threshold amplitude.

[0007] Another aspect is a method for detecting mechanical wear of gears in a crystal puller, the method including receiving time domain data from a load cell during a measurement time, where a load cell connected to the gear measures a force applied to the gear in the time domain, converting the time domain data to a frequency domain to obtain frequency domain data, where the frequency domain data includes an amplitude during the measurement time, and determining whether the amplitude exceeds a threshold amplitude.

[0008] Various refinements exist for the features noted in relation to the above aspects. Additionally, features may be incorporated into the above aspects. These refinements and additional features may exist individually or in any combination. For example, various features described below in relation to any of the illustrated embodiments may be incorporated into the above aspects alone or in any combination. [Brief description of the drawings]

[0009] [Figure 1] 1 is a schematic diagram of an example of an ingot pulling apparatus used to pull a single crystal silicon ingot from a silicon melt. [Diagram 2] FIG. 2 is a cross-sectional view of an ingot pulling apparatus. [Diagram 3] FIG. 1 is a partial view of an example of a single crystal silicon ingot grown by the Czochralski method. [Figure 4] FIG. 2 is a perspective view of a partial cross section of a lifting mechanism. [Diagram 5] 2 is a block diagram of a controller used in the control system of the ingot pulling apparatus of FIG. 1. [Figure 6] 1 is a flowchart illustrating a conversion from time domain data to frequency domain data. [Figure 7] 1 is a chart of load cell data in the time domain for a motor having parts with mechanical wear. [Figure 8] 1 is a chart of load cell data in the frequency domain for a motor having parts with mechanical wear. [Figure 9] 1 is a chart of load cell data in the frequency domain for a motor having parts with no mechanical wear. [Figure 10] A method for determining wear on gear components.

[0010] Like reference numbers in the various drawings indicate like elements. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] This application claims the benefit of U.S. Provisional Patent Application No. 63 / 269,717, filed March 22, 2022, which is incorporated by reference in its entirety.

[0012] The disclosed embodiments relate to systems and methods for monitoring and analyzing selected signals recorded by a load cell and analyzed in the frequency domain by a Fourier transform filter to ensure that characteristic signals associated with a failed part are distinguished from background noise and other ancillary signals. The analyzed signals are converted from the time domain to the frequency domain and compared to thresholds or predefined limits to determine if excessive wear has occurred on the gears or parts of the crystal puller. The analyzed signals can facilitate detection of periodic errors. Periodic errors can be due to vibrations, eccentricities, or other mechanical irregularities in the gears, bearings, or shafts of the motor, for example. The disclosed embodiments can monitor the condition of the crystal puller without stopping production, disassembling the crystal puller, or stopping the crystal puller for inspection. Furthermore, if excessive wear is detected, the crystal puller can be scheduled for maintenance without affecting the quality of the crystals and before a catastrophic failure occurs that would result in the loss of crystals in production.

[0013] An ingot pulling apparatus (more simply referred to as an "ingot pulling apparatus" or "crystal pulling apparatus") for growing a single crystal silicon ingot will be described with reference to Figures 1 to 4. Figures 1 and 2 are schematic representations of an ingot pulling apparatus generally designated "100" which pulls an ingot of single crystal silicon or semiconductor material from a melt 104. Figure 3 is a partial front view of a single crystal ingot grown, for example, by the Czochralski method in the ingot pulling apparatus 100. Figure 4 is a perspective view of the pulling mechanism.

[0014] The ingot pulling apparatus 100 includes a crystal pulling housing 108 that defines a growth chamber 152 for pulling a silicon ingot 113 from a silicon melt 104. A control system 170 controls the operation of the ingot pulling apparatus 100 and its components (including one or more gears). The ingot pulling apparatus 100 includes a crucible 102 disposed within the growth chamber 152 for holding the silicon melt 104. The crucible 102 is supported by a susceptor 106.

[0015] The crucible 102 includes a floor 129 and a sidewall 131 extending upwardly from the floor 129. The sidewall 131 is generally vertical. The floor 129 includes a curved portion of the crucible 102 that extends below the sidewall 131. Within the crucible 102 is a silicon melt 104 having a melt surface 111 (i.e., a melt-ingot interface). A susceptor 106 is supported by a shaft 105. The susceptor 106, crucible 102, shaft 105, and ingot 113 have a common longitudinal axis A or "pull axis" A.

[0016] Disposed within the ingot pulling apparatus 100 is a pulling mechanism 114 for growing and pulling an ingot 113 from the melt 104. The pulling mechanism 114 includes a pulling cable 118, a seed holder or chuck 120 coupled to one end of the pulling cable 118, and a seed crystal 122 coupled to the seed holder or chuck 120 for initiating crystal growth. One end of the pulling cable 118 is connected to a pulley or drum 117, or other suitable type of lifting mechanism, such as a shaft, and the other end is connected to the chuck 120, which holds the seed crystal 122. In operation, the seed crystal 122 is lowered into contact with the melt 104. The pulling mechanism 114 is actuated to raise the seed crystal 122, thereby pulling the single crystal ingot 113 from the melt 104.

[0017] During heating and crystal pulling, a crucible drive unit 107 (e.g., a motor) rotates the crucible 102 and susceptor 106. A crystal pulling mechanism 112 raises and lowers the crucible 102 along the pulling axis A during the growth process. As the ingot grows, the silicon melt 104 is consumed and the melt height in the crucible 102 decreases. The crucible 102 and susceptor 106 can be raised to maintain the melt surface 111 at or near the same position relative to the ingot pulling apparatus 100.

[0018] The crucible drive unit 107 can raise or lower the crucible 102 via the worm gear 109 (one of the parts that wear). The load cell 192 is suitably connected to the worm gear 109 or the crucible drive unit 107 to measure the force applied to the worm gear 109. The load cell 192 is preferably a force transducer, but may be another type of sensor. The worm gear 109 is connected in series to the rotor (not shown) of the crucible drive unit 107 by a gear or shaft (not shown). The crucible drive unit 107 may include a bearing (not shown) that supports the shaft. As used herein, the term "gears connected in series" refers to a gear train of a mechanical system formed by a combination of gears connected to other gears (i.e., the teeth of a first gear are connected to the teeth of a second gear) and gears coupled to other gears, for example, via a rotating shaft. The load cell 192 is located in the motor and is integral with the system. Thus, the load cell 192 can be located within the motor enclosure without the need for external components.

[0019] 1 and 4, the crystal drive unit 180 (e.g., a motor) can also rotate (e.g., counter-rotate) the pulling cable 118 and ingot 113 in a direction opposite to the direction that the crucible drive unit 107 rotates the crucible 102. In embodiments using uniform rotation, the crystal drive unit can rotate the pulling cable 118 in the same direction that the crucible drive unit 107 rotates the crucible 102. Additionally, the crystal drive unit raises and lowers the ingot 113 relative to the melt surface 111 as desired during the growth process.

[0020] The crystal drive unit 180 includes a rotor 182 connected to a cable take-up drum 184 by one or more gears 185 and a shaft 186. The drum 184, gear 185, and shaft 186 are connected in series. The cable 118 is wound around the drum 184 and then suspended from a pulley 188. In some embodiments, a load cell 194 is a force transducer. In some embodiments, the load cell 194 is coupled to the pulley 188 by a load cell link or anchor 190 that faces the gear. The gear 185 and shaft 186 of the rotor 182 are supported by bearings (not shown).

[0021] The ingot pulling apparatus 100 may include an inert gas system for introducing and withdrawing an inert gas, such as argon, into the growth chamber 152. The ingot pulling apparatus 100 may also include a dopant delivery system (not shown) for introducing dopants into the melt 104.

[0022] According to the Czochralski single crystal growth process, a quantity of polycrystalline silicon, i.e., polysilicon, is charged to a crucible 102 (e.g., a charge of 250 kg or more). The source of polycrystalline silicon can vary, including, for example, granular polycrystalline silicon produced by pyrolysis of silane or halosilane in a fluidized bed reactor, or polycrystalline silicon produced in a Siemens reactor. After the polycrystalline silicon is added to the crucible to form a charge, the charge is heated to a temperature equal to or greater than the melting point of silicon (e.g., about 1412° C.) to melt it. In some embodiments, the charge (i.e., melt) is heated to a temperature of at least about 1425° C., at least about 1450° C., or even at least about 1500° C. The ingot pulling apparatus 100 includes bottom insulation 110 and side insulation 124 for retaining heat within the puller 100. In the illustrated embodiment, the ingot pulling apparatus 100 includes a bottom heater 126 disposed below the crucible floor 129. The crucible 102 may be moved relatively close to the bottom heater 126 to melt the polycrystalline material charged in the crucible 102 .

[0023] To form an ingot, a seed crystal 122 is contacted with a surface 111 of the melt 104. A pulling mechanism 114 is actuated to pull the seed crystal 122 out of the melt 104. The ingot 113 includes a crown portion 142 that transitions outward from the seed crystal 122 and tapers to reach a target diameter. The ingot 113 includes a constant diameter portion of the crystal or a cylindrical body portion 145 that is grown by increasing the pulling rate. The body portion 145 of the ingot 113 is of relatively constant diameter. The ingot 113 includes a tail or end cone (not shown) where the diameter of the ingot tapers after the body 145. Once the diameter is sufficiently small, the ingot 113 is then separated from the melt 104. The ingot 113 has a central longitudinal axis A that extends through the crown portion 142 and the end of the ingot 113.

[0024] The ingot pulling apparatus 100 includes a side heater 135 and a susceptor 106 that surrounds the crucible 102 to maintain the temperature of the melt 104 during crystal growth. The side heater 135 is positioned radially outward relative to the crucible sidewall 131 as the crucible 102 moves up and down along the pulling axis A. The side heater 135 and bottom heater 126 may be any type of heater operable as described herein. In some embodiments, the heaters 135, 126 are resistive heaters. The side heater 135 and bottom heater 126 may be controlled by a control system 170 such that the temperature of the melt 104 is controlled throughout the pulling process.

[0025] The ingot pulling apparatus 100 also includes a reflector 151 (or "heat shield") disposed within the growth chamber 152, positioned above the melt 104, and covering the ingot 113 during ingot growth. The reflector 151 may be partially disposed within the crucible 102 during crystal growth. The reflector 151 defines a central passage 160 for receiving the ingot 113 as it is pulled by the pulling mechanism 114.

[0026] Reflector 151 is generally a heat shield adapted to retain heat beneath it and above the melt 104. In this regard, any reflector design and material of construction known in the art (e.g., graphite or ash crystal) may be used without limitation.

[0027] A single crystal silicon ingot 113 produced according to an embodiment of the present disclosure, and generally according to the Czochralski process, is shown in Figure 3. The ingot 113 includes a neck 116, an outwardly flared portion 142 (synonymously "crown" or "cone"), a shoulder 119, and a body 145 of constant diameter. The neck 116 is attached to a seed crystal 122 that contacts the melt and is drawn to form the ingot 113. The body 145 is suspended from the neck 116. The neck 116 terminates as the outwardly flared portion 142 of the ingot 113 begins to form.

[0028] The constant diameter portion of the ingot 113 has a perimeter 150, a central axis A parallel to the perimeter 150, and a radius R extending from the central axis A to the perimeter 150. The central axis A also passes through the outer flared portion 142 and the neck 116. The diameter of the body portion 145 may vary, and in some embodiments the diameter may be about 150 mm, about 200 mm, about 300 mm, greater than about 300 mm, about 450 mm, or even greater than about 450 mm.

[0029] The single crystal silicon ingot 113 may generally have any resistivity. The single crystal silicon ingot 113 may be doped or undoped.

[0030] Load cell 192 of crucible drive unit 107 and load cell 194 of crystal drive unit 180 are part of a measurement system used to measure the loads of crucible drive unit 107 and crystal drive unit 180. In other words, load cell 192 of crucible drive unit 107 measures the weight of the crystal supported by shaft 105, and load cell 194 of crystal drive unit 180 measures the weight of the crystal supported by pull cable 118 of crystal drive unit 180.

[0031] Rotation of the gears and shafts of the crucible drive unit 107 and crystal drive unit 180 produces vibrations that can be detected and measured in the time domain by the load cells (192, 194). Data transmitted from the load cells (192, 194) is collected by the control system 170, processed by the controller 200, and converted by an algorithm into frequency domain data to determine wear of the gears and bearings, or more generally, the components of the motors of the crucible drive unit 107 and crystal drive unit 180, as described in more detail below.

[0032] 5 is an example of a controller 200 that may be used as or as part of the control system 170. The controller 200 also functions as a detection system. The controller 200 includes a processor 202, a local memory 204, a communication interface 206, and a number of sensors 208. The number of sensors 208 includes load cells (192, 194) that are connected to the processor 202. Other embodiments may include different components, additional components, and / or may not include all of the components shown in FIG. 6.

[0033] The communications interface 206 and the processor 200 are connected to a programmable logic controller or "PLC" 174. The PLC 174 controls the operation of the motors of the crucible drive unit 107 and the crystal drive unit 180, as well as the heaters (126, 135).

[0034] The processor 202 is configured to execute instructions. For example, executable instructions are stored in the memory 204, and the processor 202 may include one or more processing units (e.g., a multi-core configuration). The one or more processing units preferably perform the respective functions of the processor 202 and execute all or a portion of the instructions. As used herein, the term "processor" refers to a central processing unit, a microprocessor, a microcontroller, a reduced instruction set circuit (RISC), an application specific integrated circuit (ASIC), a programmable logic circuit (PLC), and other circuits or processors capable of performing the functions described herein. These are merely examples and are not intended to limit the definition and / or meaning of the term "processor."

[0035] The local memory 204 stores non-transitory computer-readable instructions for the execution of the techniques described herein. Such instructions, when executed by the processor 202, cause the processor 202 to perform at least a portion of the methods described herein. In some embodiments, the memory 204 stores computer-readable instructions for providing a user interface to a user via a media output component and receiving and processing input from an input device. The memory 204 includes, but is not limited to, random access memory (RAM), such as dynamic RAM (DRAM) or static RAM (SRAM), read-only memory (ROM), erasable programmable read-only memory (EPROM), electrically erasable programmable read-only memory (EEPROM), and non-volatile RAM (NVRAM). Although illustrated separately from the processor 202, in some embodiments, the memory 204 is combined with the processor 202, such as a microcontroller or microprocessor, but may still be referred to separately. The memory types described above are merely exemplary and thus are not limiting of the types of memory that may be used to store computer programs.

[0036] In some embodiments, computing device 200 includes or is connected to an input device for receiving input from a user. An input device is any device that enables computing device 200 to receive analog and / or digital commands, instructions, or other input from a user, such as visual, audio, tactile, button presses, stylus taps, etc. Input devices may include, for example, a variable resistor, an input dial, a keyboard / keypad, a pointing device, a mouse, a stylus, a touch-sensitive panel (e.g., a touchpad or touch screen), a gyroscope, an accelerometer, a position detector, an audio input device, or any combination thereof. A single component, such as a touch screen, may function as both an output device and an input device for a media output component.

[0037] The communication interface allows the computing device 200 to communicate with remote devices and systems forming the network 210, such as remote sensors, remote databases, remote computing devices, and may include multiple communication interfaces for interacting with multiple remote devices or systems. The communication interface is a wired or wireless communication interface that allows the computing device 200 to communicate with remote devices and systems directly or over a network. The wireless communication interface may include a radio frequency (RF) transceiver, a Bluetooth adapter, a Wi-Fi transceiver, a ZigBee transceiver, a near field communication (NFC) transceiver, an infrared (IR) transceiver, and / or other devices and communication protocols for wireless communication (Bluetooth is a registered trademark of Bluetooth Special Interest Group, Kirkland, Washington, and ZigBee is a registered trademark of the ZigBee Alliance, San Ramon, California). The wired communication interface may use any suitable wired communication protocol, such as USB, RS232, I2C, SPI, analog, and proprietary I / O protocols, for direct communication. In some embodiments, the wired communication interface includes a wired network adapter that enables computing device 400 to be coupled to a network, such as the Internet, a local area network (LAN), a wide area network (WAN), a mesh network, and / or any other network for communicating with remote devices and systems via network 210.

[0038] FIG. 6 illustrates a flow chart 300 for receiving data from the load cells (192, 194), processing the data with an algorithm to obtain output data, and comparing the output data with a profile stored in memory 204 to determine whether components of the crucible drive unit 107 and the crystal drive unit 180 are experiencing mechanical wear or failure. The load cells (192, 194) transmit time domain data 302 to the processor 202. In some embodiments, the processor 202 can execute instructions to process the time domain data 302 through an algorithm to convert the time domain data 302 to frequency domain data 304. In some embodiments, the processor 202 can execute instructions to transmit the time domain data 302 to the network 210 so that one or more processors of the network 210 can execute instructions to process the time domain data 302 through an algorithm to convert the time domain data 302 to frequency domain data 304. The frequency domain data 304 is then compared to a profile 306 stored in memory 204 to determine if mechanical wear or failure has occurred in the components of the crucible drive unit 107 and the crystal drive unit 180. The profile 306 includes one or more thresholds that are compared to the frequency domain data 304. If the frequency domain data 304 is greater than the one or more thresholds, it is determined that mechanical wear or failure has occurred in the components of the crucible drive unit 107 and the crystal drive unit 180. As used herein, the terms "threshold" and "threshold value" refer to guard band limits in the frequency domain.

[0039] In some embodiments, the algorithm is a Fourier transform. In some embodiments, the algorithm is a fast Fourier transform. In some embodiments, the algorithm is a discrete Fourier transform. As used herein, the term "time domain data" refers to mathematical functions, physical signals, or time series data with respect to time. A time domain graph (shown in FIG. 7) measures data collected over a period of time. As used herein, the term "frequency domain data" refers to mathematical functions and signals with respect to frequency rather than time. While a time domain graph shows the change in a signal or data over time, a frequency domain graph (shown in FIG. 8) shows the amplitude of the data or signal within a given frequency band across a range of frequencies.

[0040] FIG. 7 shows the time domain load cell data over a particular range of crystal growth lengths L. As shown in FIG. 1, the crystal length L is the length of the constant diameter section or cylindrical body 145. In other words, the crystal length L is from the melt surface 111. The load cell data in the time domain is collected over a period T (or more generally a measurement time) during which the ingot 113 has a crystal length L between 1500 mm and 1700 mm, defining the operating conditions of the control system 170 for determining mechanical wear. In some embodiments, the operating conditions (and period T) include a crystal length L of 100% of the total crystal length. In some embodiments, the operating conditions (and period T) include a crystal length L of 80% of the total crystal length. In some embodiments, the operating conditions (and period T) include a crystal length L of 60% of the total crystal length. In some embodiments, the operating conditions (and period T) include a crystal length L of 40% of the total crystal length. In some embodiments, the operating conditions (and period T) include a crystal length L of 20% of the total crystal length.

[0041] In some embodiments, the processor 202 is configured to identify operating conditions for receiving time domain data from the load cell. In some embodiments, the processor is configured to receive time domain data throughout the crystal pulling process.

[0042] As shown in FIG. 7, the variation in weight (kg), or more generally, the variation in force data collected by the load cells (192, 194), across the components of the crucible drive unit 107 and the crystal drive unit 180, such as bearings, gears, worm gears, etc., is shown by data (D1, D2, D3, D4) across operating conditions and thus across time period T. Data D1 and D3 show the variation in weight of mechanically worn components of the crucible drive unit 107 and the crystal drive unit 180, data D2 shows the variation in weight of repaired components of the crucible drive unit 107 and the crystal drive unit 180, and data D4 shows the variation in weight of new, unworn components of the crucible drive unit 107 and the crystal drive unit 180. The variation in weight due to wear also causes vibrations detected by the load cells (192, 194) across operating conditions. As the ingot 113 gets longer, the variation in weight and the vibrations become increasingly large.

[0043] Weight variations due to mechanical wear are difficult to detect in the time domain until the mechanical wear has progressed to a state close to failure due to lack of resolution and the accompanying vibrations and noise present in the system.

[0044] As shown in FIG. 8 and FIG. 9, the load cell data in the time domain is analyzed through a Fourier transform filter in the frequency domain to generate frequency amplitudes or peaks ω corresponding to the variations due to wear. FIG. 8 shows amplitudes ω1, ω2, ω3, ω4 corresponding to the weight variations of the parts due to mechanical wear. Each amplitude (ω1, ω2, ω3, ω4) has a frequency F(ω4) corresponding to the degree of wear. Furthermore, the load cells (190, 192) can sense the vibration of the parts connected in series, which corresponds to an increase in frequency (shown on the X-axis). Thus, one load cell can generate multiple force frequency amplitudes (ω1, ω2, ω3, ω4) for all the parts connected in series using a Fourier transform filter. Each amplitude ω1, ω2, ω3, ω4 is included in the frequency domain data 304 and compared to a threshold value stored in the memory 204.

[0045] 9, a new part, or more generally a part that does not exhibit mechanical wear, will not have detectable amplitudes in the frequency domain data 304. Thus, by collecting time domain data 302 from the load cells (192, 194) and processing the time domain data 302 with an algorithm, frequency domain data 304 is obtained that can be compared and analyzed to determine if the part has experienced wear.

[0046] A method 402 for detecting mechanical wear of gears, or more generally of components of the crucible drive unit 107 and crystal drive unit 180, includes the following steps: receiving time domain data 302 from the load cells (190, 192) during a measurement time, converting the time domain data 302 in the frequency domain to frequency domain data 304, and determining 406 whether the amplitude exceeds a threshold amplitude. If it is determined that mechanical wear has occurred, preventive maintenance can be performed on the component before mechanical failure occurs.

[0047] The computer systems described herein may include additional, less, or alternative functionality, including those described elsewhere herein. The computer systems described herein may include or be implemented by or through computer-executable instructions stored on a non-transitory computer-readable medium or media.

[0048] The logic flows depicted in the figures do not require the particular order shown, or sequential order, unless otherwise specified. Additionally, other steps may be provided or omitted from the described flows, and other components may be added or removed from the described systems. The above embodiments described in detail are merely examples or possible embodiments, and other combinations, additions, or alternatives exist within the scope of the present disclosure. Additionally, the specific naming of components, capitalization of terms, attributes, data structures, or other programming or structural aspects are not required or important. The mechanisms for implementing the present disclosure or its features may have different names, formats, or protocols. Additionally, the system may be implemented by a combination of hardware and software, as previously described, or may be implemented entirely with hardware elements. Additionally, the division of functionality between various system components described herein is merely exemplary and not required. Functions performed by a single system component may instead be performed by multiple components, and functions performed by multiple components may instead be performed by a single component.

[0049] Approximate language used throughout this specification and claims may be applied to modify any quantitative expression that may vary permissibly without resulting in a change in the basic function to which it pertains. Thus, values ​​modified by terms such as "about" or "substantially" are not limited to the precise value specified. In at least some cases, the approximation may correspond to the precision of the means of measuring the value.

[0050] When introducing elements of this disclosure or embodiments thereof, the articles "a," "an," "the," and "said" mean that there are one or more elements. The terms "comprising," "including," "containing," and "having" are inclusive and mean that there may be additional elements other than the listed elements. The use of specific directional terms (e.g., "top," "bottom," "side," etc.) is for convenience of description and does not require a particular orientation of the articles being described.

[0051] Since various changes may be made in the above structures and methods without departing from the scope of the disclosure, all matter set forth in the above description and shown in the accompanying drawings should be interpreted as illustrative and not limiting.

Claims

1. 1. A crystal pulling system comprising: a crucible for containing the molten semiconductor material; Cables and gears; a crystal disposed at the end of the cable and a motor for pulling the cable and the crystal out of the melt; a load cell connected to the gear and measuring the force applied to the gear; and A control system including a processor connected to the load cell, the processor configured to process data received from the load cell, the processor comprising: receiving time domain data from the load cell over a measurement time during the crystal pulling process; Transforming the time domain data into frequency domain data, the frequency domain data including force frequency amplitudes over a measurement time; and determining whether the force frequency amplitude exceeds a threshold; A crystal pulling system including a control system configured as above.

2. 10. The system of claim 1, wherein the load cell reads a predetermined number of data samples over a measurement period.

3. The system of claim 1 , wherein the processor is configured to identify operating conditions for which the processor receives time domain data from the load cell.

4. 4. The system of claim 3, wherein the operating conditions include the crystal being pulled to any of the following: 100% of the total crystal length, 80% of the total crystal length, 60% of the total crystal length, and 20% of the total crystal length.

5. The system of claim 1 , wherein the processor applies an algorithm to transform the time domain data into frequency domain data.

6. The system of claim 1 , wherein the processor applies one of a Fourier transform, a fast Fourier transform, and a discrete Fourier transform to convert the time domain data to frequency domain data.

7. 10. The system of claim 1, wherein the load cell measures at least one of the force on the gear, the vibration of the gear as the gear rotates, and the vibration of the gear of the motor.

8. The system of claim 1 , wherein the load cell is internal to the gear and motor.

9. 9. The system of claim 8, wherein the load cell is suspended from the gear by a tensioned anchor.

10. 10. The system of claim 9, wherein the load cell measures vibration of a gear connected in series with the motor.

11. The processor further comprises: converting the time domain data to frequency domain data, the frequency domain data including a plurality of force frequency amplitudes; and The system of claim 10 , configured to determine whether one or more of the plurality of amplitudes exceeds a threshold amplitude.

12. 12. The system of claim 11, wherein each of the plurality of amplitudes corresponds to a vibration of a gear.

13. 1. A detection system for detecting mechanical wear of gears in a crystal puller, comprising: a load cell connected to the gear and measuring the force applied to the gear in the time domain; and A control system including a processor connected to the load cell, the processor configured to process data received from the load cell, the processor comprising: receiving time domain data from the load cell over a measurement time during the crystal pulling process; directing the processor to convert the time domain data into frequency domain data, the frequency domain data including amplitude over a measurement time; directing the processor to determine whether the amplitude exceeds a threshold amplitude; A detection system including a control system configured to:

14. 14. The system of claim 13, wherein the gear is connected in series with a gear of a motor of a pulling mechanism, the pulling mechanism including a drum having a wrapped cable for pulling the crystal from the molten semiconductor material.

15. 15. The system of claim 14, wherein the gears are connected in series by an axle, shaft, or worm gear.

16. 14. The system of claim 13, wherein the gear is connected to a motor of a crucible assembly, the crucible assembly including a shaft that rotates the crucible during the crystal pulling process.

17. 14. The system of claim 13, wherein the load cell measures vibration of the gear during rotation of the gear.

18. 1. A method for detecting mechanical wear of gears in a crystal puller, comprising: receiving time domain data over a measurement time from a load cell, the load cell being connected to a gear and measuring a force applied to the gear in the time domain; Transforming the time domain data into frequency domain data, the frequency domain data including amplitude over a measurement time; and determining whether the amplitude exceeds a threshold amplitude.

19. 20. The method of claim 18, wherein the processor applies a Fourier transform to convert the time domain data to frequency domain data in the frequency domain.

20. 20. The method of claim 18, wherein the amplitude is greater for worn gears than for intact gears.

Images