A thin ingot resistivity detection method based on an eddy current method probe

Abstract

This invention discloses a method for detecting the resistivity of thin ingots based on an eddy current probe, belonging to the field of semiconductor measurement technology. It solves the problem of measurement deviations in the resistivity of thin ingots under certain conditions. The method includes: performing electrical testing on the thin ingot to be tested to obtain its calculated surface resistivity; identifying the type of thin ingot based on its calculated surface resistivity; calculating the skin depth of the thin ingot based on the skin effect; setting multiple sets of control thin ingots similar to the thin ingot to be tested; performing eddy current testing on these control ingots; calculating the compensation coefficient of the control ingots based on the test results; calculating a fitting equation based on the compensation coefficient and writing it into a host computer; and calculating the actual resistivity of the thin ingot to be tested based on the fitting equation. This invention achieves accurate measurement of the resistivity of the thin ingot to be tested, and also realizes automated and intelligent measurement of the resistivity of the thin ingot to be tested.

Description

Technical Field

[0001] This invention belongs to the field of semiconductor testing technology, specifically a method for detecting the resistivity of thin ingots based on an eddy current probe. Background Technology

[0002] Thin crystal ingots are sheet-like crystalline materials used in the semiconductor, photovoltaic, or special metal industries. They possess high purity and single-crystal or polycrystalline structures, making them a key basic material for manufacturing devices such as chips and solar cells. Eddy current testing is a method that utilizes electromagnetic induction between an electromagnetic field and a metal for detection. It is one of the basic methods for non-destructive testing of metallic materials. Electromagnetic induction is sensitive to many test parameters, making eddy current testing a versatile method. However, the measurement data is also affected by various "interference factors." Therefore, accurate and reliable test results can only be achieved by fully utilizing useful information and more effectively suppressing interference.

[0003] However, when the actual thickness of the thin ingot is less than the penetration depth, the traditional method will obtain completely different eddy current signals when measuring thin ingots of different thicknesses with the same resistivity. Consequently, the measured resistivity obtained by inverse solution will also be very different, and the accuracy of resistivity measurement cannot be guaranteed.

[0004] Therefore, this invention proposes a method for detecting the resistivity of thin ingots based on an eddy current probe. Summary of the Invention

[0005] The purpose of this invention is to propose a method for detecting the resistivity of thin ingots based on an eddy current probe, so as to solve the problems mentioned in the background art.

[0006] To achieve the above objectives, the present invention adopts the following technical solution:

[0007] A method for detecting the resistivity of thin ingots based on an eddy current probe, the method comprising:

[0008] Step S1: Perform electrical testing on the thin crystal ingot to be tested and analyze it to obtain the calculated surface resistivity of the thin crystal ingot to be tested;

[0009] Step S2: Identify the type of thin ingot based on the calculated surface resistivity of the thin ingot to be tested, and calculate the skin depth of the thin ingot to be tested by combining the skin effect.

[0010] Step S3: Set up multiple sets of control thin crystal ingots similar to the thin crystal ingot to be tested, perform eddy current method tests on multiple sets of control thin crystal ingots, and calculate the compensation coefficient of the control thin crystal ingots based on the test results.

[0011] Step S4: Calculate the fitting equation based on the compensation coefficient and write it into the host computer. Calculate the actual resistivity of the thin ingot to be tested based on the fitting equation.

[0012] Further, step S1 includes the following sub-steps:

[0013] Step S11: Measure the thickness HD and surface area of ​​the thin crystal ingot to be tested.

[0014] Step S12: Compare the surface area of ​​the thin crystal ingot with the thin crystal ingot surface area threshold. If the surface area of ​​the thin crystal ingot is less than or equal to the thin crystal ingot surface area threshold, then select a line segment with a fixed distance on the surface of the thin crystal ingot to be tested, and set up the first detection point, the second detection point, the third detection point and the fourth detection point on the line segment and execute step S14.

[0015] Step S13: If the surface area of ​​the thin crystal ingot is greater than the surface area threshold of the thin crystal ingot, then four detection points are set at the four ends of the upper surface of the thin crystal ingot to be tested, and are labeled in clockwise order as: first detection point, second detection point, third detection point and fourth detection point.

[0016] Step S14: Apply current probes above the first and fourth detection points, apply voltage probes above the second and third detection points, pass a constant current I between the two current probes, and pass a constant voltage U between the two voltage probes.

[0017] Furthermore, step S1 also includes the following sub-steps:

[0018] Step S15: Identify the real-time current value between the two current probes using an ammeter, and identify the real-time voltage value between the two voltage probes using a real-time voltmeter.

[0019] Step S16: Calculate the surface resistivity DZL of the thin ingot to be tested using the formula, which is as follows:

[0020] DZL = U / I × HD × XZ; where XZ is the correction factor;

[0021] Step S17: Change the constant current between the two current probes and change the constant voltage between the two voltage probes. Repeat steps S15-S16 multiple times and calculate the surface resistivity of multiple sets of thin crystal ingots to be tested.

[0022] Step S18: Sum the surface resistivity of multiple sets of thin crystal ingots to be tested, and take the average to obtain the classical calculated surface resistivity JDZ of the wave to be tested.

[0023] Furthermore, if the thickness of the thin ingot to be tested is less than ten times the probe spacing, then the formula for calculating XZ is:

[0024] ;

[0025] If the thickness of the thin crystal ingot to be tested is greater than or equal to ten times the probe spacing, then XZ equals 1.

[0026] Further, step S2 includes the following sub-steps:

[0027] Step S21: Obtain the calculated surface resistivity of the thin crystal ingot to be tested, match the calculated surface resistivity with a known database, and identify the type of thin crystal ingot to be tested.

[0028] Step S22: Based on the type of thin ingot, the corresponding thin ingot conductivity DD and thin ingot magnetic permeability CD are identified using the Internet of Things.

[0029] Step S23: Set the probe parameters corresponding to the eddy current probe used in the eddy current detection method; wherein, the probe parameters include the probe type of the eddy current probe and the coil structure of the excitation coil bound to the eddy current probe.

[0030] Step S24: Apply alternating current to the excitation coil bound to the eddy current probe and identify the excitation frequency PL of the excitation coil; wherein, the excitation frequency of the excitation coil is consistent with the frequency of the alternating current applied to the excitation coil.

[0031] Step S25: Here, the concept of skin effect is introduced. Based on the calculation formula of skin effect, the skin depth QS of the thin ingot to be tested corresponding to the eddy current probe is calculated. The specific calculation formula is as follows:

[0032] .

[0033] Further, step S3 includes the following sub-steps:

[0034] Step S31: Obtain the skin depth of the thin crystal ingot to be tested, and record three times the skin depth as the penetration depth of the thin crystal ingot to be tested.

[0035] Step S32: Obtain the calculated surface resistivity and surface area of ​​the thin crystal ingot to be tested, and use the calculated surface resistivity and surface area of ​​the thin crystal ingot as parameters of the reference thin crystal ingot.

[0036] Step S33: Using the penetration depth as the peak thickness of the reference thin crystal ingot, different reference thin crystal ingots have a stepped thickness variation. The reference thin crystal ingots are numbered as i, i=1, 2, ..., z, where z is a positive integer.

[0037] Furthermore, step S3 also includes the following sub-steps:

[0038] Step S34: Select the control thin crystal ingot with the smallest thickness, take the upper surface of the control thin crystal ingot as the detection surface, identify the edge of the detection surface, record the area with a fixed width from the edge to the center of the detection surface as the danger area, record the area other than the danger area as the normal area, divide the normal area into multiple grids with fixed side lengths, and randomly select n grids as detection grids.

[0039] Step S35: The eddy current signal of the detection grid is measured sequentially using the eddy current probe with the parameters described in steps S23-S24; the calculated resistivity of the reference thin crystal ingot is obtained based on the inverse solution of the eddy current signal; the detection resistivity is obtained by summing the detection resistivity corresponding to the n detection grids and taking the average.

[0040] Furthermore, step S3 also includes the following sub-steps:

[0041] Step S36: Compare the measured resistivity of the reference thin ingot with the calculated surface resistivity. If the measured resistivity of the reference thin ingot is equal to the calculated surface resistivity, proceed directly to step S37. If the measured resistivity of the reference thin ingot is not equal to the calculated surface resistivity, record the thickness of the reference thin ingot and the measured resistivity.

[0042] Step S37: Select a reference thin ingot with the next thin ingot thickness, repeat steps S34 to S36, and replace the grid division process with directly selecting the detection grid at the same position in the current reference thin ingot; finally, multiple sets of detection resistivity and thin ingot thickness are obtained.

[0043] Step S38: The compensation coefficient of the reference thin ingot with the corresponding thin ingot thickness is obtained by dividing the detected resistivity of the reference thin ingot by the calculated surface resistivity.

[0044] Furthermore, the inverse process for calculating resistivity is as follows:

[0045] Step S351: Construct the expression ZK for the eddy current signal based on the definition of the eddy current signal;

[0046] Eddy current detection essentially involves inducing eddy currents in a thin crystal ingot using an alternating magnetic field. The resistivity of the thin crystal ingot affects the distribution and intensity of the eddy currents, which in turn affects the impedance detected by the eddy current probe. Therefore, the impedance induced by the eddy current probe is expressed as:

[0047] ZK = S + X × j; where ZK is a complex number, S represents the real part, X represents the imaginary part, and j is a constant;

[0048] Step S352, when the eddy current probe is close to the control thin ingot, the impedance induced by the eddy current probe is expressed as:

[0049] In the formula, k is a constant, π is pi, and JD is the calculated resistivity.

[0050] Step S353: Solve the two impedance equations simultaneously to obtain the expression for calculating resistivity JD. Substitute the expression into the equation to obtain the calculated resistivity. The specific expression for calculating resistivity is as follows:

[0051] In the formula, |ZK| is the magnitude of the impedance. .

[0052] Further, step S4 includes the following sub-steps:

[0053] Step S41: Obtain the compensation coefficient and thickness of the control thin ingot;

[0054] Step S42: Using the thickness of the thin ingot as the independent variable and the compensation coefficient as the dependent variable, a trend diagram of the relationship between the independent and dependent variables is constructed. The trend diagram is combined with a function fitting algorithm to obtain the corresponding fitting equation.

[0055] Step S43: Measure the thickness of the thin crystal ingot to be tested, input the thickness of the thin crystal ingot into the host computer, and detect the thin crystal ingot to be tested through the eddy current probe; compare the thickness of the thin crystal ingot with the penetration depth. If the thickness of the thin crystal ingot is greater than or equal to the penetration depth, the detected resistivity of the thin crystal ingot to be tested is directly output.

[0056] Step S44: If the thickness of the thin crystal ingot is less than the penetration depth, the resistivity of the thin crystal ingot to be tested is sent to the host computer and processed and output after fitting the equation.

[0057] In summary, due to the adoption of the above technical solution, the beneficial effects of the present invention are:

[0058] 1. This invention performs electrical testing on the thin crystal ingot to be tested and analyzes it to obtain the calculated surface resistivity of the thin crystal ingot; identifies the type of thin crystal ingot based on the calculated surface resistivity of the thin crystal ingot to be tested, and calculates the skin depth of the thin crystal ingot to be tested in combination with the skin effect; thereby realizing the confirmation of the corresponding skin depth of the thin crystal ingot to be tested.

[0059] 2. This invention sets up multiple sets of control thin crystal ingots similar to the thin crystal ingot to be tested, performs eddy current testing on the multiple sets of control thin crystal ingots, calculates the compensation coefficient of the control thin crystal ingots based on the test results, and then completes the calculation of all the prerequisites for the fitting equation.

[0060] 3. This invention calculates the fitting equation based on the compensation coefficient and writes it into the host computer. Combined with the fitting equation, the actual resistivity of the thin crystal ingot to be tested is calculated. This invention ensures the accuracy of the measurement results and also realizes the automated and intelligent measurement of the resistivity of the thin crystal ingot to be tested. Attached Figure Description

[0061] To facilitate understanding by those skilled in the art, the present invention will be further described below with reference to the accompanying drawings.

[0062] Figure 1 This is a flowchart illustrating the overall method of the present invention;

[0063] Figure 2 This is a flowchart of the algorithm for fitting the equation in this invention;

[0064] Figure 3 This is a flowchart illustrating the compensation process in this invention.

[0065] Figure 4 This is a trend graph showing the relationship between the independent and dependent variables of the fitting function in this invention;

[0066] Figure 5 This is a schematic diagram of the computer device in this invention. Detailed Implementation

[0067] The technical solution of the present invention will be clearly and completely described below with reference to the embodiments. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0068] Example 1: Please refer to Figures 1-4 As shown, the technical solution provided by the present invention is: a thin ingot resistivity detection method based on eddy current probe, which obtains the surface resistivity of the thin ingot to be tested by electrical detection, calculates the skin depth of the thin ingot to be tested by the skin equation, sets multiple reference thin ingots in combination with the size and skin depth of the thin ingot to be tested, constructs a fitting equation by analyzing the detected resistivity of the reference thin ingots, and realizes accurate measurement of the thin ingot to be tested in an intelligent and automated manner based on the fitting equation;

[0069] In this invention, the method for detecting the resistivity of thin ingots is specifically as follows:

[0070] Step S1: Perform electrical testing on the thin crystal ingot to be tested and analyze it to obtain the calculated surface resistivity of the thin crystal ingot to be tested;

[0071] In this invention, step S1 includes the following sub-steps:

[0072] Step S11: Measure the thickness HD and surface area of ​​the thin crystal ingot to be tested.

[0073] Step S12: Compare the surface area of ​​the thin crystal ingot with the thin crystal ingot surface area threshold. If the surface area of ​​the thin crystal ingot is less than or equal to the thin crystal ingot surface area threshold, then select a line segment with a fixed distance on the surface of the thin crystal ingot to be tested, and set up the first detection point, the second detection point, the third detection point and the fourth detection point on the line segment and execute step S14.

[0074] Step S13: If the surface area of ​​the thin crystal ingot is greater than the surface area threshold of the thin crystal ingot, then four detection points are set at the four ends of the upper surface of the thin crystal ingot to be tested, and are labeled in clockwise order as: first detection point, second detection point, third detection point and fourth detection point.

[0075] Step S14: Apply current probes to the first and fourth detection points, apply voltage probes to the second and third detection points, pass a constant current I between the two current probes, and pass a constant voltage U between the two voltage probes.

[0076] It should be noted that the constant voltage U and constant current I, the pressure between the current probe and the voltage probe and the thin ingot under test are controlled between one Newton and five Newtons, so as to avoid damaging the thin ingot under test or introducing contact resistance.

[0077] Step S15: Identify the real-time current value between the two current probes using an ammeter, and identify the real-time voltage value between the two voltage probes using a real-time voltmeter.

[0078] Step S16: Calculate the surface resistivity DZL of the thin ingot to be tested using the formula, which is as follows:

[0079] DZL = U / I × HD × XZ; where XZ is a correction factor, the value of which is related to the probe spacing JJ and the size of the thin ingot to be measured, specifically:

[0080] If the thickness of the thin ingot to be tested is less than ten times the probe spacing, then the formula for calculating XZ is:

[0081] ;

[0082] If the thickness of the thin ingot to be tested is greater than or equal to ten times the probe spacing, then XZ is considered as 1;

[0083] Step S17: Change the constant current between the two current probes and change the constant voltage between the two voltage probes. Repeat steps S15-S16 multiple times and calculate the surface resistivity of multiple sets of thin crystal ingots to be tested.

[0084] Step S18: Sum the surface resistivity of multiple sets of thin crystal ingots to be tested, and take the average to obtain the classical calculated surface resistivity JDZ of the wave to be tested.

[0085] Step S2: Identify the type of thin ingot based on the calculated surface resistivity of the thin ingot to be tested, and calculate the skin depth of the thin ingot to be tested by combining the skin effect.

[0086] In this invention, step S2 includes the following sub-steps:

[0087] Step S21: Obtain the calculated surface resistivity of the thin ingot to be tested, match the calculated surface resistivity with a known database, and identify the type of thin ingot to be tested; specifically, the types of thin ingots include semiconductor materials such as monocrystalline silicon and silicon carbide.

[0088] Step S22: Based on the type of thin ingot, the corresponding thin ingot conductivity DD and thin ingot magnetic permeability CD are identified using the Internet of Things.

[0089] Step S23: Set the probe parameters corresponding to the eddy current probe used in the eddy current detection method; wherein, the probe parameters include the probe type of the eddy current probe and the coil structure of the excitation coil bound to the eddy current probe.

[0090] Specifically, in this invention, the preferred probe type of the eddy current probe is a differential eddy current probe, and the preferred coil structure of the excitation coil is a double coil structure. Compared with traditional probe types and coil structures, this can improve sensitivity and anti-interference capability. In practice, the coil diameter can be set to 2mm, the spacing between the two coils can be set to 1mm, and the distance between the eddy current probe and the thin crystal ingot to be tested can be set to 0.1mm.

[0091] Step S24: Apply alternating current to the excitation coil bound to the eddy current probe and identify the excitation frequency PL of the excitation coil; wherein, the excitation frequency of the excitation coil is consistent with the frequency of the alternating current applied to the excitation coil.

[0092] Step S25: Here, the concept of skin effect is introduced. Based on the calculation formula of skin effect, the skin depth QS of the thin ingot to be tested corresponding to the eddy current probe is calculated. The specific calculation formula is as follows:

[0093] ;

[0094] Specifically, the skin effect is the penetration depth of an alternating electromagnetic field in a conductor when it decays to 1 / e (approximately 37%) of its surface value.

[0095] Step S3: Set up multiple sets of control thin crystal ingots similar to the thin crystal ingot to be tested, perform eddy current method tests on multiple sets of control thin crystal ingots, and calculate the compensation coefficient of the control thin crystal ingots based on the test results.

[0096] In this invention, step S3 includes the following sub-steps:

[0097] Step S31: Obtain the skin depth of the thin ingot to be tested, and record three times the skin depth as the penetration depth of the thin ingot to be tested; it should be noted that for the thin ingot to be tested, at the skin depth, the eddy current density of the thin ingot to be tested is 37% of the surface value, and at three times the skin depth, the eddy current density of the thin ingot to be tested is 5% of the surface value;

[0098] Step S32: Obtain the calculated surface resistivity and surface area of ​​the thin crystal ingot to be tested, and use the calculated surface resistivity and surface area of ​​the thin crystal ingot as parameters of the reference thin crystal ingot; In this invention, the upper surface of all reference thin crystal ingots is considered to have the same shape.

[0099] Step S33: Using the penetration depth as the peak thickness of the reference thin crystal ingot, different reference thin crystal ingots have a stepped thickness variation. The reference thin crystal ingots are numbered as i, i=1, 2, ..., z, where z is a positive integer.

[0100] For example, the thickness distribution of the reference thin crystal ingot can be: 0.5mm, 1mm, 1.5mm, ..., 8.5mm, 9mm;

[0101] It should be noted that when the thickness of the thin ingot to be tested is greater than the penetration depth, the eddy currents are mainly concentrated in the surface layer near the excitation coil. The material state inside the sample has very little influence on the eddy current signal. For this type of relatively thick thin ingot to be tested, as long as the surface properties are consistent, the test results will be very accurate.

[0102] When the thickness of the thin ingot is less than the penetration depth, the eddy current cannot be confined to the surface layer, and may even penetrate the entire thickness or form a unique circulation path within a limited range, which will affect the inductive impedance of the coil. Even if the resistivity of the surface area is the same, the change of its induced magnetic field is different, which depends not only on the resistivity of the surface layer, but also on the relationship between the thickness of the thin ingot under test and the probe test depth. Therefore, thin ingots under test with the same resistivity but different thicknesses will give completely different eddy current signals. This invention mainly addresses this situation.

[0103] Step S34: Select the control thin crystal ingot with the smallest thickness, use the upper surface of the control thin crystal ingot as the detection surface, identify the edge of the detection surface, and mark the area with a fixed width from the edge to the center of the detection surface as the danger area, and mark the area other than the danger area as the normal area. Divide the normal area into multiple grids with fixed side lengths, and randomly select n grids as detection grids; specifically, the fixed width is preferably 10mm, the side length of the grid is preferably 1mm, and n is preferably 3.

[0104] Step S35: The eddy current signal of the detection grid is measured sequentially using the eddy current probe with the parameters described in steps S23-S24; the calculated resistivity of the reference thin crystal ingot is obtained based on the inverse solution of the eddy current signal; the detection resistivity is obtained by summing the detection resistivity corresponding to the n detection grids and taking the average.

[0105] The inverse process for calculating resistivity in this invention is as follows:

[0106] Step S351: Construct the expression ZK for the eddy current signal based on the definition of the eddy current signal;

[0107] Eddy current detection essentially involves inducing eddy currents in a thin crystal ingot using an alternating magnetic field. The resistivity of the thin crystal ingot affects the distribution and intensity of the eddy currents, which in turn affects the impedance detected by the eddy current probe. Therefore, the impedance induced by the eddy current probe is expressed as:

[0108] ZK = S + X × j; where ZK is a complex number, S represents the real part, X represents the imaginary part, and j is a constant;

[0109] Step S352, when the eddy current probe is close to the control thin ingot, the impedance induced by the eddy current probe is expressed as:

[0110] In the formula, k is a constant, which is related to the parameters of the eddy current probe and coil; π is pi; and JD is the calculated resistivity (i.e., the inverse target).

[0111] Step S353: Solve the two impedance equations simultaneously to obtain the expression for calculating resistivity JD. Substitute the expression into the inverse solution to obtain the calculated resistivity. The specific expression for calculating resistivity is as follows:

[0112] In the formula, |ZK| is the magnitude of the impedance. ;

[0113] Step S36: Compare the measured resistivity of the reference thin ingot with the calculated surface resistivity. If the measured resistivity of the reference thin ingot is equal to the calculated surface resistivity, proceed directly to step S37. If the measured resistivity of the reference thin ingot is not equal to the calculated surface resistivity, record the thickness of the reference thin ingot and the measured resistivity.

[0114] Step S37: Select a reference thin ingot with the next thin ingot thickness, repeat steps S34 to S36, and replace the grid division process with directly selecting the detection grid at the same position in the current reference thin ingot; finally, multiple sets of detection resistivity and thin ingot thickness are obtained.

[0115] Step S38: The compensation coefficient of the reference thin crystal ingot with the corresponding thin crystal ingot thickness is obtained by dividing the detected resistivity of the reference thin crystal ingot by the calculated surface resistivity.

[0116] Specifically, the relationship between the thickness of the thin ingot and the compensation coefficient is shown in Table 1:

[0117] Table 1:

[0118]

[0119] Step S4: Calculate the fitting equation based on the compensation coefficient and write it into the host computer; then calculate the actual resistivity of the thin ingot to be tested based on the fitting equation.

[0120] In this invention, step S4 includes the following sub-steps:

[0121] Step S41: Obtain the compensation coefficient and thickness of the control thin ingot;

[0122] Step S42, please refer to Figure 4 As shown, a trend graph of the relationship between the independent and dependent variables is constructed using the thickness of the thin ingot as the independent variable (i.e., the X-axis) and the compensation coefficient as the dependent variable (i.e., the Y-axis). The trend graph is combined with a function fitting algorithm to obtain the corresponding fitting equation, and the fitting equation is written into the host computer.

[0123] Step S43: Measure the thickness of the thin crystal ingot to be tested, input the thickness of the thin crystal ingot into the host computer, and detect the thin crystal ingot to be tested through the eddy current probe; compare the thickness of the thin crystal ingot with the penetration depth. If the thickness of the thin crystal ingot is greater than or equal to the penetration depth, the detected resistivity of the thin crystal ingot to be tested is directly output.

[0124] Step S44: If the thickness of the thin crystal ingot is less than the penetration depth, the resistivity of the thin crystal ingot to be tested is sent to the host computer and processed and output after fitting the equation.

[0125] Example 2: As Figure 5 As shown, this embodiment provides a computer device, which may include a processor, a communication interface, a memory, and a communication bus. The processor, communication interface, and memory communicate with each other via the communication bus. The processor can call logical instructions in the memory to execute a thin ingot resistivity detection method based on an eddy current probe. This method includes: performing electrical testing on the thin ingot to be tested to obtain the calculated surface resistivity of the thin ingot; identifying the type of thin ingot based on the calculated surface resistivity, and calculating the skin depth of the thin ingot based on the skin effect; setting multiple sets of control thin ingots similar to the thin ingot to be tested, performing eddy current testing on the multiple sets of control thin ingots, and calculating the compensation coefficient of the control thin ingots based on the test results; calculating a fitting equation based on the compensation coefficient and writing it into a host computer; and calculating the actual resistivity of the thin ingot to be tested based on the fitting equation.

[0126] Furthermore, when the logical instructions in the aforementioned memory can be implemented as software functional units and sold or used as independent products, they can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of this application, in essence, or the part that contributes to the prior art, or a portion of the technical solution, can be embodied in the form of a software product. This computer software product is stored in a storage medium and includes several instructions to cause a computer device (which may be a personal computer, server, or network device, etc.) to execute all or part of the steps of the methods described in the various embodiments of this application. The aforementioned storage medium includes various media capable of storing program code, such as USB flash drives, portable hard drives, read-only memory (ROM), random access memory (RAM), magnetic disks, or optical disks.

[0127] On the other hand, this application also provides a computer program product, which includes a computer program stored on a computer-readable storage medium. The computer program includes program instructions, and when the program instructions are executed by a computer, the computer is able to execute a thin ingot resistivity detection method based on an eddy current probe provided by the above methods. The method includes: performing electrical testing on the thin ingot to be tested and analyzing it to obtain the calculated surface resistivity of the thin ingot to be tested; identifying the type of thin ingot to be tested based on the calculated surface resistivity of the thin ingot to be tested, and calculating the skin depth of the thin ingot to be tested in combination with the skin effect; setting multiple sets of control thin ingots similar to the thin ingot to be tested, performing eddy current testing on the multiple sets of control thin ingots, and calculating the compensation coefficient of the control thin ingots based on the test results; calculating the fitting equation based on the compensation coefficient and writing it into a host computer, and calculating the actual resistivity of the thin ingot to be tested in combination with the fitting equation.

[0128] In another aspect, this application also provides a computer-readable storage medium storing a computer program thereon, which, when executed by a processor, performs the aforementioned method for detecting the resistivity of thin ingots based on eddy current probes. The method includes: performing electrical testing on the thin ingot to be tested and analyzing it to obtain the calculated surface resistivity of the thin ingot; identifying the type of thin ingot based on the calculated surface resistivity of the thin ingot, and calculating the skin depth of the thin ingot based on the skin effect; setting multiple sets of control thin ingots similar to the thin ingot to be tested, performing eddy current testing on the multiple sets of control thin ingots, and calculating the compensation coefficient of the control thin ingots based on the test results; calculating a fitting equation based on the compensation coefficient and writing it into a host computer, and calculating the actual resistivity of the thin ingot to be tested based on the fitting equation.

[0129] The device embodiments described above are merely illustrative. The units described as separate components may or may not be physically separate. The components shown as units may or may not be physical units; that is, they may be located in one place or distributed across multiple network units. Some or all of the modules can be selected to achieve the purpose of this embodiment according to actual needs. Those skilled in the art can understand and implement this without any creative effort.

[0130] Through the above description of the embodiments, those skilled in the art can clearly understand that each embodiment can be implemented by means of software plus necessary general-purpose hardware platforms, and of course, it can also be implemented by hardware. Based on this understanding, the above technical solutions, in essence or the part that contributes to the prior art, can be embodied in the form of a software product. This computer software product can be stored in a computer-readable storage medium, such as ROM / RAM, magnetic disk, optical disk, etc., and includes several instructions to cause a computer device (which may be a personal computer, server, or network device, etc.) to execute the methods described in the various embodiments or some parts of the embodiments.

[0131] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of this application.

Claims

1. A method for detecting the resistivity of thin ingots based on an eddy current probe, characterized in that, The methods include: Step S1: Perform electrical testing on the thin crystal ingot to be tested and analyze it to obtain the calculated surface resistivity of the thin crystal ingot to be tested; Step S2: Identify the type of thin ingot based on the calculated surface resistivity of the thin ingot to be tested, and calculate the skin depth of the thin ingot to be tested by combining the skin effect. Step S3: Set up multiple sets of control thin crystal ingots similar to the thin crystal ingot to be tested, perform eddy current method tests on multiple sets of control thin crystal ingots, and calculate the compensation coefficient of the control thin crystal ingots based on the test results. Step S3 includes the following sub-steps: Step S31: Obtain the skin depth of the thin crystal ingot to be tested, and record three times the skin depth as the penetration depth of the thin crystal ingot to be tested. Step S32: Obtain the calculated surface resistivity and surface area of ​​the thin crystal ingot to be tested, and use the calculated surface resistivity and surface area of ​​the thin crystal ingot as parameters of the reference thin crystal ingot. Step S33: Using the penetration depth as the peak thickness of the reference thin crystal ingot, different reference thin crystal ingots have a stepped thickness variation. The reference thin crystal ingots are numbered as i, i=1, 2, ..., z, where z is a positive integer. Step S34: Select the control thin crystal ingot with the smallest thickness, take the upper surface of the control thin crystal ingot as the detection surface, identify the edge of the detection surface, record the area with a fixed width from the edge to the center of the detection surface as the danger area, record the area other than the danger area as the normal area, divide the normal area into multiple grids with fixed side lengths, and randomly select n grids as detection grids. Step S35: The eddy current signal of the detection grid is measured sequentially using the eddy current probe with the parameters described in steps S23-S24; the calculated resistivity of the reference thin crystal ingot is obtained based on the inverse solution of the eddy current signal; the detection resistivity is obtained by summing the detection resistivity corresponding to the n detection grids and taking the average. Step S36: Calculate the surface resistivity by comparing it with the detected resistivity of the thin crystal ingot; If the measured resistivity of the reference thin crystal ingot is equal to the calculated surface resistivity, then proceed directly to step S37; If the measured resistivity of the control thin ingot is not equal to the calculated surface resistivity, then record the thickness of the control thin ingot and the measured resistivity. Step S37: Select a reference thin ingot with the next thin ingot thickness, repeat steps S34 to S36, and replace the grid division process with directly selecting the detection grid at the same position in the current reference thin ingot; finally, multiple sets of detection resistivity and thin ingot thickness are obtained. Step S38: The compensation coefficient of the reference thin crystal ingot with the corresponding thin crystal ingot thickness is obtained by dividing the detected resistivity of the reference thin crystal ingot by the calculated surface resistivity. Step S4: Calculate the fitting equation based on the compensation coefficient and write it into the host computer. Calculate the actual resistivity of the thin ingot to be tested based on the fitting equation.

2. The method for detecting the resistivity of thin ingots based on an eddy current probe according to claim 1, characterized in that, Step S1 includes the following sub-steps: Step S11: Measure the thickness HD and surface area of ​​the thin crystal ingot to be tested. Step S12: Compare the surface area of ​​the thin crystal ingot with the thin crystal ingot surface area threshold. If the surface area of ​​the thin crystal ingot is less than or equal to the thin crystal ingot surface area threshold, then select a line segment with a fixed distance on the surface of the thin crystal ingot to be tested, and set up the first detection point, the second detection point, the third detection point and the fourth detection point on the line segment and execute step S14. Step S13: If the surface area of ​​the thin crystal ingot is greater than the surface area threshold of the thin crystal ingot, then four detection points are set at the four ends of the upper surface of the thin crystal ingot to be tested, and are labeled in clockwise order as: first detection point, second detection point, third detection point and fourth detection point. Step S14: Apply current probes above the first and fourth detection points, apply voltage probes above the second and third detection points, pass a constant current I between the two current probes, and pass a constant voltage U between the two voltage probes.

3. The method for detecting the resistivity of thin ingots based on an eddy current probe according to claim 2, characterized in that, Step S1 further includes the following sub-steps: Step S15: Identify the real-time current value between the two current probes using an ammeter, and identify the real-time voltage value between the two voltage probes using a real-time voltmeter. Step S16: Calculate the surface resistivity DZL of the thin ingot to be tested using the formula, which is as follows: DZL = U / I × HD × XZ; where XZ is the correction factor; Step S17: Change the constant current between the two current probes and change the constant voltage between the two voltage probes. Repeat steps S15-S16 multiple times and calculate the surface resistivity of multiple sets of thin crystal ingots to be tested. Step S18: Sum the surface resistivity of multiple sets of thin crystal ingots to be tested, and take the average to obtain the classical calculated surface resistivity JDZ of the wave to be tested.

4. The method for detecting the resistivity of thin ingots based on an eddy current probe according to claim 3, characterized in that, If the thickness of the thin ingot to be tested is less than ten times the probe spacing, then the formula for calculating XZ is: In the formula, JJ is the probe spacing; If the thickness of the thin crystal ingot to be tested is greater than or equal to ten times the probe spacing, then XZ equals 1.

5. The method for detecting the resistivity of thin ingots based on an eddy current probe according to claim 1, characterized in that, Step S2 includes the following sub-steps: Step S21: Obtain the calculated surface resistivity of the thin crystal ingot to be tested, match the calculated surface resistivity with a known database, and identify the type of thin crystal ingot to be tested. Step S22: Based on the type of thin ingot, the corresponding thin ingot conductivity DD and thin ingot magnetic permeability CD are identified using the Internet of Things. Step S23: Set the probe parameters corresponding to the eddy current probe used in the eddy current detection method; wherein, the probe parameters include the probe type of the eddy current probe and the coil structure of the excitation coil bound to the eddy current probe. Step S24: Apply alternating current to the excitation coil bound to the eddy current probe and identify the excitation frequency PL of the excitation coil; wherein, the excitation frequency of the excitation coil is consistent with the frequency of the alternating current applied to the excitation coil. Step S25: Calculate the skin depth QS of the thin ingot to be tested corresponding to the eddy current probe based on the skin effect calculation formula. The specific calculation formula is as follows: 。 6. The method for detecting the resistivity of thin ingots based on an eddy current probe according to claim 1, characterized in that, The inverse process for calculating resistivity is as follows: Step S351: Construct the expression ZK for the eddy current signal based on the definition of the eddy current signal; Eddy current detection involves inducing eddy currents in a thin crystal ingot using an alternating magnetic field. The resistivity of the thin crystal ingot affects the distribution and intensity of the eddy currents, which in turn affects the impedance detected by the eddy current probe. Therefore, the impedance induced by the eddy current probe is expressed as: ZK = S + X × j; where ZK is a complex number, S represents the real part, X represents the imaginary part, and j is a constant; Step S352, when the eddy current probe is close to the control thin ingot, the impedance induced by the eddy current probe is expressed as: In the formula, k is a constant, π is pi, JD is the calculated resistivity, CD is the permeability of the thin ingot, and PL is the excitation frequency of the excitation coil. Step S353: Solve the two impedance equations simultaneously to obtain the expression for calculating resistivity JD. Substitute the expression into the equation to obtain the calculated resistivity. The specific expression for calculating resistivity is as follows: In the formula, |ZK| is the magnitude of the impedance. .

7. The method for detecting the resistivity of thin ingots based on an eddy current probe according to claim 1, characterized in that, Step S4 includes the following sub-steps: Step S41: Obtain the compensation coefficient and thickness of the control thin ingot; Step S42: Using the thickness of the thin ingot as the independent variable and the compensation coefficient as the dependent variable, a trend diagram of the relationship between the independent and dependent variables is constructed. The trend diagram is combined with a function fitting algorithm to obtain the corresponding fitting equation. Step S43: Measure the thickness of the thin crystal ingot to be tested, input the thickness of the thin crystal ingot into the host computer, and detect the thin crystal ingot to be tested through the eddy current probe; The thickness of the thin crystal ingot is compared with the penetration depth. If the thickness of the thin crystal ingot is greater than or equal to the penetration depth, the resistivity of the thin crystal ingot under test is directly output. Step S44: If the thickness of the thin crystal ingot is less than the penetration depth, the resistivity of the thin crystal ingot to be tested is sent to the host computer and processed and output after fitting the equation.

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