A solar cell silicon wafer eddy current sensor

Abstract

The application provides a solar cell silicon wafer eddy current sensor and relates to the technical field of eddy current sensors.The eddy current sensor comprises a single-chip microcomputer, an infrared temperature detector and a probe detection assembly connected with the single-chip microcomputer.The single-chip microcomputer is used for acquiring the temperature of a sensor probe and the target temperature of a to-be-detected solar cell silicon wafer, acquiring a plurality of first sheet resistances of the to-be-detected solar cell silicon wafer, correcting each first sheet resistance according to the temperature of the sensor probe and a preset probe temperature compensation model corresponding to the temperature of the sensor probe, acquiring a second sheet resistance corresponding to each first sheet resistance, correcting each second sheet resistance according to the target temperature and a preset silicon wafer temperature compensation model corresponding to the target temperature, acquiring a third sheet resistance corresponding to each second sheet resistance, calculating the average value of each third sheet resistance, and obtaining a corresponding target sheet resistance.The two types of temperatures, i.e., the temperature of the sensor probe and the target temperature, can be accurately measured and compensated respectively, and the problem that the measured value of the sheet resistance has poor repeatability on a production line is solved.

Description

Technical Field

[0001] This invention relates to the field of eddy current sensor technology, and more specifically, to an eddy current sensor for a solar cell silicon wafer. Background Technology

[0002] Currently, in solar cell production, the quality of diffusion is determined by testing the sheet resistance (SRT) of the silicon wafer surface. SRT testing monitors the depth, concentration, and surface uniformity of ion implantation, playing a crucial role in solar cell production. SRT measurement is mainly divided into two categories: contact four-point probe (4PP) and non-contact eddy current sensors. Eddy current sensors are based on the principle of electromagnetic induction, utilizing the eddy current effect to quickly and non-contactly measure the SRT of the tested solar cell silicon wafer. However, due to limitations in probe manufacturing processes, the change in coil inductance is not linearly correlated with the SRT value, and probe temperature... Temperature changes significantly affect inductance, and the target silicon wafer temperature also greatly influences the measurement results (taking a resistivity of 1 Ω·cm at 23℃ as an example, a 5-degree change in the silicon wafer results in a 3.65% change rate). Existing eddy current sensor temperature compensation technologies, such as CN109470931A, compensate for both probe temperature and ambient temperature, using a temperature sensor integrated into the CPU to measure the ambient temperature. However, these technologies do not consider the actual situation where the target silicon wafer temperature and the ambient temperature differ significantly on the production line, leading to poor repeatability of sheet resistance measurements on the production line. Summary of the Invention

[0003] The purpose of this invention is to provide an eddy current sensor for solar cell silicon wafers, which can accurately measure both probe temperature and target temperature, and compensate for each separately, thereby solving the problem of poor repeatability of sheet resistance measurements on the production line.

[0004] The embodiments of the present invention are implemented as follows:

[0005] This application provides a solar cell silicon wafer eddy current sensor, including a microcontroller and an infrared thermometer and probe detection assembly connected to the microcontroller;

[0006] An infrared thermometer is used to monitor the target temperature of the silicon wafer under test, and transmit the target temperature to the microcontroller. The silicon wafer under test is a solar cell wafer.

[0007] The probe detection component is used to monitor and obtain the sensor probe temperature and first sheet resistance, and transmit the sensor probe temperature and first sheet resistance to the microcontroller;

[0008] The microcontroller is used to obtain the sensor probe temperature, the target temperature of the silicon wafer under test, and multiple first sheet resistances of the silicon wafer under test. Based on the sensor probe temperature and the corresponding preset probe temperature compensation model, each first sheet resistance is corrected to obtain multiple second sheet resistances. Based on the target temperature and the corresponding preset silicon wafer temperature compensation model, each second sheet resistance is corrected to obtain multiple third sheet resistances. Finally, the average value of each third sheet resistance is calculated to obtain the target sheet resistance.

[0009] The beneficial effects of this invention are as follows: the target temperature of the silicon wafer to be tested is obtained by an infrared thermometer, the sensor probe temperature of the eddy current sensor probe is obtained by a probe detection component, and finally the sheet resistance of the silicon wafer to be tested obtained by the probe detection component is corrected by the target temperature and the sensor probe temperature. On the one hand, the purpose of monitoring the sheet resistance of the silicon wafer is achieved, and on the other hand, the accuracy of the overall device is improved by correcting the sheet resistance by the target temperature and the sensor probe temperature.

[0010] Based on the above technical solution, the present invention can be further improved as follows.

[0011] Furthermore, the aforementioned probe detection component includes a temperature monitoring circuit and a sheet resistance monitoring circuit;

[0012] Temperature monitoring circuit, used to monitor and obtain the temperature of sensor probe, and transmit the sensor probe temperature to microcontroller;

[0013] The sheet resistance monitoring circuit is used to monitor and obtain multiple first sheet resistances and transmit the multiple first sheet resistances to the microcontroller.

[0014] The beneficial effects of adopting the above-mentioned further solution are: the temperature of the sensor probe is obtained through the temperature monitoring circuit and transmitted to the microcontroller in real time; the first sheet resistance is obtained and transmitted to the microcontroller through the sheet resistance monitoring circuit.

[0015] Furthermore, the temperature monitoring circuit mentioned above includes an RTD resistor and an RTD circuit, and the RTD circuit is also connected to a microcontroller.

[0016] The RTD circuit includes a processor U2 and a resistor R18 and a capacitor C18 connected to the processor U2. Pins 8, 10, 11 and 12 of the processor U2 are all connected to the RTD resistor. Pins 10 and 11 of the processor U2 are connected to the two ends of the capacitor C18. Pins 4 and 5 of the processor U2 are connected to one end of the resistor R18. Pins 6 and 7 of the processor U2 are connected to the other end of the resistor R18.

[0017] The beneficial effect of adopting the above-mentioned further solution is that it enables the acquisition of sensor probe temperature and its real-time transmission to the microcontroller.

[0018] Furthermore, the aforementioned sheet resistance monitoring circuit includes a sheet resistance sensor head, a sheet resistance sensor signal processing circuit, and an AD conversion circuit;

[0019] The sheet resistance sensor head is used to obtain the target signal corresponding to the first sheet resistance and transmit the target signal to the sheet resistance sensor signal processing circuit.

[0020] The sheet resistance sensor signal processing circuit is used to receive the target signal, obtain the corresponding target analog signal based on the target signal, and transmit the target analog signal to the AD conversion circuit.

[0021] The AD conversion circuit is used to receive the target analog signal, convert the target analog signal into the target digital signal, and transmit the target digital signal to the microcontroller.

[0022] The microcontroller is also used to receive the target digital signal and obtain the sensor probe temperature based on the target digital signal.

[0023] The beneficial effect of adopting the above-mentioned further scheme is that it enables the microcontroller to obtain the target digital signal in digital form, and finally obtains the first sheet impedance through the microcontroller. Attached Figure Description

[0024] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of the present invention and should not be regarded as a limitation on the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0025] Figure 1 This is a schematic diagram showing the connection of the microcontroller and peripheral circuits in an embodiment of the present invention;

[0026] Figure 2 This is a schematic diagram of the connection of the AD conversion circuit in an embodiment of the present invention;

[0027] Figure 3 This is a schematic diagram of the communication circuit connection in an embodiment of the present invention;

[0028] Figure 4 This is a schematic diagram of the connection of the RTD circuit in an embodiment of the present invention;

[0029] Figure 5 This is a schematic diagram of the connection of the sheet resistance sensor head in an embodiment of the present invention;

[0030] Figure 6 This is a schematic diagram of the connection of the sheet resistance sensor signal processing circuit in an embodiment of the present invention;

[0031] Figure 7This is a schematic diagram of the connection of the battery silicon wafer eddy current sensor in an embodiment of the present invention. Detailed Implementation

[0032] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. The components of the embodiments of the present invention described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.

[0033] Therefore, the following detailed description of the embodiments of the invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the invention without inventive effort are within the scope of protection of the invention.

[0034] It should be noted that similar labels and letters in the following figures indicate similar items. Therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures.

[0035] Example

[0036] This embodiment provides a solar cell silicon wafer eddy current sensor, including a microcontroller and an infrared thermometer and probe detection assembly connected to the microcontroller;

[0037] The process involves obtaining the target temperature of the silicon wafer under test using an infrared thermometer, then obtaining the sensor probe temperature of the eddy current sensor probe using a probe detection assembly, and finally correcting the sheet resistance of the silicon wafer under test obtained by the probe detection assembly using the target temperature and the sensor probe temperature. This achieves the purpose of monitoring the sheet resistance of the silicon wafer and improves the overall accuracy of the device by correcting the sheet resistance using the target temperature and the sensor probe temperature.

[0038] The microcontroller is used to obtain the sensor probe temperature, the target temperature of the silicon wafer under test, and multiple first sheet resistances of the silicon wafer under test. Based on the sensor probe temperature and the corresponding preset probe temperature compensation model, each first sheet resistance is corrected to obtain multiple second sheet resistances. Based on the target temperature and the corresponding preset silicon wafer temperature compensation model, each second sheet resistance is corrected to obtain multiple third sheet resistances. The average value of each third sheet resistance is calculated to obtain the target sheet resistance.

[0039] The microcontroller can be programmed to implement the functions. The microcontroller model can be STM32F405RGT6. For details on the microcontroller's peripheral circuitry, please refer to [link / reference needed]. Figure 1The microcontroller's pins 5 and 6 are connected to crystal oscillator Y1, capacitor C21, and capacitor C22; pins 31 and 47 are connected to capacitors C16 and C17. The processor U1 is also connected to the microcontroller; see details in [link to documentation]. Figure 2 The processor U1 can be an AD7732BRUZ. The processor U1 is also connected to resistors R3, R11, R14, R15, R16, R17, capacitors C1, C3, C8, C9, C11, C2, and diode D1.

[0040] Specifically, the aforementioned microcontroller is also equipped with a communication circuit, which includes a processor U4. The processor U4 model can be SP3232EEY-L / TR. For details, please refer to [link / reference needed]. Figure 3 and Figure 1 , Figure 3 In the process, the processor U4 is also connected to capacitors C19, C19, C19, C19, and C19, etc., thereby realizing communication between the microcontroller and the infrared thermometer and probe detection components to achieve the purpose of data signal exchange.

[0041] Specifically, when the eddy current sensor in this application is used on an assembly line, the microcontroller calculates the first sheet resistance of the silicon wafer by using one or more sets of sheet resistance signals of the silicon wafer under test, sensor probe temperature, and target temperature. The first sheet resistance is then corrected according to a preset probe temperature compensation model and sensor probe temperature to obtain a second sheet resistance. The second sheet resistance is then corrected according to a preset silicon wafer temperature compensation model and target temperature to obtain a third sheet resistance. This process is repeated until multiple sets of data are processed to obtain multiple third sheet resistances. These multiple third sheet resistances are then calculated, such as by averaging, to obtain the average sheet resistance of the entire silicon wafer, i.e., the target sheet resistance. Finally, the multiple third sheet resistances and the corresponding target sheet resistance are transmitted to the host computer for storage to complete the measurement of a single silicon wafer.

[0042] Among them, the probe temperature compensation model is derived from a large amount of experimental data through data modeling; the silicon wafer temperature compensation model is based on the silicon wafer temperature correction coefficient table of the National Institute of Metrology of China.

[0043] An infrared thermometer is used to monitor the target temperature of the silicon wafer under test, and transmit the target temperature to the microcontroller. The silicon wafer under test is a solar cell wafer.

[0044] Among them, the infrared thermometer can be an online high-precision infrared thermometer of model CSlaser-LT-CF1, which has a short response time of 150ms and a temperature resolution of 0.1℃. Its response time and resolution meet the requirements for online use. It achieves communication with the microcontroller through serial communication, so that the microcontroller can obtain the target temperature of the silicon wafer of the battery under test.

[0045] The probe detection component is used to monitor and obtain the sensor probe temperature and first sheet resistance, and transmit the sensor probe temperature and first sheet resistance to the microcontroller.

[0046] Optionally, the probe detection assembly mentioned above includes a temperature monitoring circuit and a sheet resistance monitoring circuit;

[0047] Temperature monitoring circuit, used to monitor and obtain the temperature of sensor probe, and transmit the sensor probe temperature to microcontroller;

[0048] The temperature monitoring circuit obtains the temperature of the sensor probe and transmits it to the microcontroller in real time.

[0049] Optionally, the temperature monitoring circuit mentioned above includes an RTD resistor and an RTD circuit, and the RTD circuit is also connected to a microcontroller.

[0050] The RTD resistor can be a PT100. The PT100 is placed close to the probe of the eddy current sensor. The temperature data of the sensor probe is acquired by the PT100 and then processed by the RTD circuit before being transmitted to the microcontroller.

[0051] Specifically, the connection of the RTD circuit can be found in [reference needed]. Figure 4 The temperature monitoring circuit includes an RTD resistor and an RTD circuit, and the RTD circuit is also connected to a microcontroller.

[0052] The RTD circuit includes a processor U2 and a resistor R18 and a capacitor C18 connected to the processor U2. Pins 8, 10, 11 and 12 of the processor U2 are all connected to the RTD resistor. Pins 10 and 11 of the processor U2 are connected to the two ends of the capacitor C18. Pins 4 and 5 of the processor U2 are connected to one end of the resistor R18. Pins 6 and 7 of the processor U2 are connected to the other end of the resistor R18.

[0053] The sheet resistance monitoring circuit is used to monitor and obtain multiple first sheet resistances and transmit the multiple first sheet resistances to the microcontroller.

[0054] Optionally, the above-mentioned sheet resistance monitoring circuit includes a sheet resistance sensor head, a sheet resistance sensor signal processing circuit, and an AD conversion circuit;

[0055] The sheet resistance sensor head is used to obtain the target signal corresponding to the first sheet resistance and transmit the target signal to the sheet resistance sensor signal processing circuit.

[0056] For details on the connection method of the sheet resistance sensor head, please refer to [link / reference]. Figure 5 The target signal is transmitted to the sheet resistance sensor signal processing circuit through the sheet resistance sensor head to realize the signal processing of the target signal.

[0057] The sheet resistance sensor signal processing circuit is used to receive the target signal, obtain the corresponding target analog signal based on the target signal, and transmit the target analog signal to the AD conversion circuit.

[0058] For details on the connection method between the sheet resistance sensor signal processing circuit and the sheet resistance sensor head, please refer to [link / reference]. Figure 6 and Figure 5 The target signal is processed by the sheet resistance sensor signal processing circuit to make the target signal more stable and standardized, thereby obtaining the target analog signal corresponding to the target signal.

[0059] The AD conversion circuit is used to receive the target analog signal, convert the target analog signal into the target digital signal, and transmit the target digital signal to the microcontroller.

[0060] The microcontroller is also used to receive the target digital signal and obtain the sensor probe temperature based on the target digital signal.

[0061] For details on the connection method of the AD conversion circuit, please refer to [link / reference]. Figure 2 , Figure 2 In the processor U1, pin 13 is connected to the sheet resistance sensor signal processing circuit to convert the target analog signal in analog form into the target digital signal in digital form. Through the AD conversion circuit, the target digital signal is connected to the microcontroller to transmit the target digital signal to the microcontroller, so that the microcontroller can obtain the value of the first sheet resistance.

[0062] It will be apparent to those skilled in the art that this application is not limited to the details of the exemplary embodiments described above, and that this application can be implemented in other specific forms without departing from the spirit or essential characteristics of this application. Therefore, the embodiments should be considered illustrative and non-limiting in all respects, and the scope of this application is defined by the appended claims rather than the foregoing description. Thus, all variations falling within the meaning and scope of equivalents of the claims are intended to be included within this application. No reference numerals in the claims should be construed as limiting the scope of the claims.

Claims

1. A solar cell silicon wafer eddy current sensor, characterized in that, Includes a microcontroller and an infrared thermometer and probe detection assembly connected to the microcontroller; The infrared thermometer is used to monitor the target temperature of the silicon wafer under test and transmit the target temperature to the microcontroller. The silicon wafer under test is a solar cell wafer. The probe detection component is used to monitor and obtain the sensor probe temperature and the first sheet resistance, and transmit the sensor probe temperature and the first sheet resistance to the microcontroller; The microcontroller is used to obtain the sensor probe temperature, the target temperature of the silicon wafer under test, and multiple first sheet resistances of the silicon wafer under test. It corrects each first sheet resistance according to the sensor probe temperature and the preset probe temperature compensation model corresponding to the sensor probe temperature to obtain multiple second sheet resistances. It also corrects each second sheet resistance according to the target temperature and the preset silicon wafer temperature compensation model corresponding to the target temperature to obtain multiple third sheet resistances. Finally, it calculates the average value of each third sheet resistance to obtain the target sheet resistance. The pre-set silicon wafer temperature compensation model is established based on the silicon wafer temperature correction coefficient table.

2. The solar cell silicon wafer eddy current sensor according to claim 1, characterized in that, The probe detection assembly includes a temperature monitoring circuit and a sheet resistance monitoring circuit; The temperature monitoring circuit is used to monitor and obtain the temperature of the sensor probe, and transmit the temperature of the sensor probe to the microcontroller; The sheet resistance monitoring circuit is used to monitor and obtain multiple first sheet resistances and transmit the multiple first sheet resistances to the microcontroller.

3. The solar cell silicon wafer eddy current sensor according to claim 2, characterized in that, The temperature monitoring circuit includes an RTD resistor and an RTD circuit, and the RTD circuit is also connected to the microcontroller. The RTD circuit includes a processor U2 and a resistor R18 and a capacitor C18 connected to the processor U2. Pins 8, 10, 11 and 12 of the processor U2 are all connected to the RTD resistor. Pins 10 and 11 of the processor U2 are connected to the two ends of the capacitor C18. Pins 4 and 5 of the processor U2 are connected to one end of the resistor R18. Pins 6 and 7 of the processor U2 are connected to the other end of the resistor R18.

4. The solar cell silicon wafer eddy current sensor according to claim 2, characterized in that, The sheet resistance monitoring circuit includes a sheet resistance sensor head, a sheet resistance sensor signal processing circuit, and an AD conversion circuit. The sheet resistance sensor head is used to obtain the target signal corresponding to the first sheet resistance and transmit the target signal to the sheet resistance sensor signal processing circuit. The sheet resistance sensor signal processing circuit is used to receive the target signal, obtain the corresponding target analog signal based on the target signal, and transmit the target analog signal to the AD conversion circuit. The AD conversion circuit is used to receive the target analog signal, convert the target analog signal into a target digital signal, and transmit the target digital signal to the microcontroller. The microcontroller is also used to receive the target digital signal and obtain the temperature of the sensor probe based on the target digital signal.

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