Resistivity testing device and method

Abstract

The invention provides a resistivity testing device and method, and belongs to the technical field of semiconductor detection. The device comprises a bearing platform, a probe module, an imaging unit and a control unit. The probe module is driven by the actuator and is used for executing a detection action with a specific push-in amount on the surface of the wafer. The imaging unit is used for collecting microscopic needle mark images left on the calibration sample by the probe in the calibration stage. The control unit recognizes the diameter of the needle mark and compares the diameter of the needle mark with a preset ideal contact interval, and then the push-in quantity parameter of the actuator is automatically corrected based on sectional type feedback logic. According to the method, the quantitative mapping between the microstructure and the macroscopic motion control is established, so that the real-time monitoring and active optimization of the probe contact quality are realized, and the long-term stability of the resistivity test data is remarkably improved.

Description

Technical Field

[0001] This disclosure relates to the field of semiconductor manufacturing and testing equipment technology, and in particular to a resistivity testing device and method. Background Technology

[0002] In semiconductor integrated circuit manufacturing processes, resistivity and sheet resistance are key indicators for measuring the electrical performance of wafer substrates, epitaxial layers, ion-implanted layers, and metal deposition layers. The four-point probe (4PP) method is widely used in in-line process monitoring due to its simple measurement principle and reliable data. In related technologies, a four-point probe test device typically includes a chuck holding the wafer and a probe head containing four probes. During testing, the probe head descends, and all four probes simultaneously contact the wafer surface. To ensure that the measuring current can penetrate the naturally formed insulating oxide layer on the wafer surface and establish a good ohmic contact, the probes must continue to move downwards a specific distance after contacting the wafer surface. This distance is known in the industry as "push-in" or "overdrive." The mechanical pressure generated by this push-in forces the probe tip to undergo a slight lateral slip on the wafer surface, thereby physically scraping away the oxide layer.

[0003] In existing methods, resistivity testing equipment typically uses an open-loop approach to control the probe insertion depth. Specifically, when creating a test recipe, the equipment engineer sets a fixed insertion depth value (e.g., 100 micrometers or 150 micrometers) based on experience. During subsequent production testing, the equipment mechanically executes this fixed insertion depth regardless of how many times the probe has been used. For probe lifespan management, existing methods primarily rely on a contact count counter; when the probe reaches a preset threshold (e.g., 5000 uses), the system prompts for probe replacement. This approach assumes that the probe wear process is linear and predictable, and that the surface hardness and oxide layer thickness of all wafers are consistent.

[0004] However, existing operating methods suffer from serious drawbacks closely related to the instability of probe contact. Specifically, the micro-geometry of the probe tip inevitably changes during thousands of contacts and scrapes. For example, tungsten tips may become blunt due to wear, leading to an increase in the tip's radius of curvature; or they may become contaminated due to the accumulation of metal debris such as aluminum and copper. Under a fixed push-in depth, the blunted tip significantly increases the contact area with the wafer, resulting in a decrease in contact pressure per unit area. According to the principles of contact mechanics, insufficient pressure may prevent the probe from effectively penetrating the oxide layer, resulting in extremely high and unstable contact resistance. This directly manifests as drastic fluctuations or false open circuits in the measured resistivity data. On the other hand, if the tip breaks and becomes abnormally sharp, or if the Z-axis zero point drifts, a fixed push-in depth may apply excessive pressure, causing the tip to penetrate too deeply, resulting in irreversible physical damage to the lattice structure of the wafer surface, and even affecting device yield. Because existing equipment lacks the ability to sense and adjust for changes in such micro-contact states in real time, problems are often only discovered after test data has deviated significantly from specifications, resulting in a large number of wafer retests and potential scrap risks. Summary of the Invention

[0005] This disclosure aims to solve the aforementioned technical problems existing in the prior art, namely: due to the lack of real-time monitoring and closed-loop feedback mechanism for the micro-contact state of the probe, when the probe wears or its state changes, the fixed push amount cannot maintain stable electrical contact, which in turn causes large fluctuations in resistivity test data, reduced accuracy, and potential wafer damage.

[0006] The technical solution disclosed herein is implemented as follows: In a first aspect, this disclosure provides a resistivity testing apparatus, the apparatus comprising: A carrier platform for carrying wafers, the wafers including calibration samples for parameter calibration and product-under-test wafers for performance testing; A probe module includes a probe and an actuator that drives the probe to move in a direction perpendicular to the wafer surface, the actuator being configured to drive the probe to contact the surface of the wafer according to a push-in amount set value; An imaging unit is configured to image the needle marks formed by the probe on the surface of the calibration sample; and The control unit is communicatively connected to the carrier platform, the probe module, and the imaging unit. The control unit is configured to control the imaging unit to acquire an image of the needle mark and determine the diameter data of the needle mark, compare the diameter data with a preset standard diameter range, and generate a correction command based on the comparison result to adjust the push-in amount setting value of the actuator until the diameter data of the needle mark falls within the preset standard diameter range. The final confirmed push-in amount setting value is then locked for subsequent resistivity testing of the wafer under test.

[0007] In some examples, the imaging unit includes a microscope objective and an image sensor, wherein the microscope objective has an optical magnification of not less than 200x.

[0008] In some examples, the imaging unit further includes a coaxial illumination system configured to generate light rays parallel to the optical axis of the microscope objective.

[0009] In some examples, the actuator is a closed-loop controlled piezoelectric actuator or a voice coil motor.

[0010] In some examples, the standard diameter range preset in the control unit is 20 micrometers to 24 micrometers.

[0011] In some examples, the control unit adjusts the push-in amount setpoint based on the diameter data in the following way: When the diameter data is less than 18 micrometers, the push-in amount setting value is adjusted to the first high-order value; When the diameter data is greater than or equal to 18 micrometers and less than 20 micrometers, the push-in amount setting value is adjusted to the second median value; When the diameter data is greater than 24 micrometers and less than or equal to 26 micrometers, the push-in amount setting value is adjusted to the third lowest value. When the diameter data is greater than 26 micrometers, the push-in amount setting value is adjusted to the fourth lowest value. Wherein, the first high-order value is greater than the second median value, the second median value is greater than the current push amount setting value, the third low-order value is less than the current push amount setting value, and the fourth extremely low value is less than the third low-order value.

[0012] In some examples, the first high-order value is set to 0.45 mm, the second median value is set to 0.30 mm, the third low-order value is set to 0.10 mm, and the fourth very low-order value is set to 0.05 mm.

[0013] In some examples, the control unit is also equipped with an abnormal alarm module. If the diameter data of the needle mark still does not fall within the preset standard diameter range after a predetermined number of adjustments, or if the diameter data is greater than 26 micrometers and the adjustment still does not improve the situation, the abnormal alarm module triggers the device to stop and issues a probe abnormality prompt.

[0014] In some examples, the image processing performed by the control unit to determine the diameter of the needle mark includes edge detection and geometric fitting.

[0015] In a second aspect, this disclosure provides a resistivity testing method, performed using the resistivity testing apparatus according to the first aspect, the method comprising: The calibration sample is mounted on the support platform; The probe is driven to contact the surface of the calibration sample to form a needle mark based on the current push-in amount setting; Acquire an image of the needle mark and determine the diameter data of the needle mark; Compare the diameter data with a preset standard diameter range; Based on the comparison results, a correction instruction is generated to adjust the push-in amount setting value until the diameter data of the needle mark falls within the preset standard diameter range; The final confirmed push-in amount setting is locked for subsequent resistivity testing of the wafer under test.

[0016] This disclosure provides a resistivity testing apparatus and method. First, it significantly improves the stability of resistivity test data. By maintaining the physical characteristic of the probe mark diameter within an optimal range, it ensures that the contact resistance stored at the probe tip-wafer interface is at its lowest and most stable state, resulting in a substantial reduction in the resistivity standard deviation, as shown in experimental data. Second, it enables intelligent management and extension of probe lifespan. Compared to traditional fixed-number replacements, this disclosure allows for compensation for slight probe wear by increasing the push-in depth, enabling the probe to maintain acceptable testing capabilities even in the early stages of dulling, thus improving consumable utilization. Finally, it effectively reduces the risk of wafer damage. The system can promptly identify excessively large probe marks caused by excessive push-in depth or probe abnormalities, and prevents severe mechanical damage to expensive product wafers by automatically retracting the push-in depth or triggering an alarm shutdown, ensuring production yield. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of the overall structure of the resistivity testing device with adaptive closed-loop adjustment function provided in the embodiments of this disclosure.

[0018] Figure 2 This is a schematic diagram of a needle mark microscopic image acquired by the imaging unit in an embodiment of this disclosure.

[0019] Figure 3 This is a comparative experimental result diagram showing the stability of resistivity test data before and after adaptive adjustment using the device disclosed in this embodiment.

[0020] Figure 4 This is a schematic flowchart of a resistivity testing method with adaptive closed-loop adjustment function provided in an embodiment of this disclosure. Detailed Implementation

[0021] The technical solutions in this disclosure will now be clearly and completely described with reference to the accompanying drawings.

[0022] This disclosure proposes a resistivity testing device 100 with adaptive closed-loop adjustment function, aiming to solve the problem of uncontrollable contact state caused by probe wear or mechanical drift in traditional four-probe testing by introducing a microscopic visual feedback mechanism. (Refer to...) Figure 1 The resistivity testing device 100 mainly consists of four core subsystems: a support platform 20, a probe module 30, an imaging unit 40, and a control unit 50. To ensure suitability in semiconductor manufacturing environments, the entire device is typically housed in a chassis with electromagnetic shielding and an active vibration isolation system to eliminate interference from external environmental noise on the measurement of weak voltage signals and high-magnification microscopic imaging.

[0023] First, regarding the support platform 20, it is the physical foundation of the entire testing system. This platform is equipped with a highly flat vacuum adsorption chuck, the surface of which is typically coated with a hard ceramic or anodized aluminum layer and has precision concentric or multi-hole array vacuum channels. This design ensures that both the calibration sample 10 used for calibration and the actual test wafer 11 are firmly adsorbed and forcibly flattened under vacuum pressure after being placed on the chuck. This is crucial for subsequent micron-level Z-axis control, because if the wafer's warpage is not eliminated, it will directly add to the push-in error. A high-precision XYZ-Theta four-axis motion mechanism is connected below the support platform 20. The X and Y axes typically use air bearing stages or high-precision crossed roller guides, driven by linear motors, and work with a linear encoder for fully closed-loop position feedback, ensuring that the wafer's positioning accuracy in the horizontal plane is better than 1 micron. The Theta axis is used to adjust the crystal orientation angle of the wafer, ensuring that the probe array is parallel to the wafer's feature lines (such as dicing lines).

[0024] Secondly, the probe module 30, suspended above the support platform 20, is the actuator for performing electrical measurements. The core component of this module is a probe card containing four probes 31. The probes 31 are typically made of tungsten carbide (WC), a material widely used due to its high hardness and good conductivity, but also prone to oxidation or aluminum shavings adhesion when in contact with the silicon wafer. These four probes 31 are arranged linearly and equally spaced (typically with a spacing of 1 mm or less), and are defined as current probes and voltage probes, respectively. To achieve precise downward pressure, the probe module 30 is connected to a high-performance Z-axis actuator 32. In a preferred embodiment of this disclosure, the Z-axis actuator 32 abandons the traditional stepper motor and lead screw structure, instead employing a direct-drive voice coil motor (VCM) or a piezoelectric actuator. The voice coil motor features zero hysteresis, high response speed, and extremely high force control sensitivity. Combined with a high-resolution optical encoder, the Z-axis actuator 32 can control the vertical position of the probe with nanometer-level resolution. Furthermore, the Z-axis actuator 32 integrates a load cell or senses the instant the probe contacts the wafer surface by monitoring current, thereby establishing a precise Z-axis zero-point reference frame. This is a prerequisite for achieving accurate "overdrive" control. Overdrive refers to the amount of displacement the probe makes after contacting the wafer surface; this displacement is converted into contact pressure through the elastic deformation of the probe cantilever beam.

[0025] To enable the system to "see" microscopic contact traces, an imaging unit 40 is integrated into the device. (See reference...) Figure 1 This unit is rigidly mounted above the support platform 20, typically arranged side-by-side with the probe module 30, or sharing the XY motion coordinate system via a precision gantry. The design challenge of the imaging unit 40 lies in its ability to clearly distinguish objects such as... Figure 2The pinhole 60 shown is only a few micrometers in diameter, and the silicon wafer surface has high reflectivity. Therefore, the imaging unit 40 in this embodiment employs a specific optical configuration. First, it includes a high-resolution industrial-grade digital high-definition camera 41, such as a 5-megapixel or higher resolution CCD / CMOS sensor with a global shutter, to ensure image free of ghosting and rich detail. Second, it is matched with a high-magnification microscope objective 42, whose optical magnification is set to 500x. 500x is chosen to ensure sufficient pixels within the field of view to characterize a pinhole of approximately 20 micrometers, thereby guaranteeing the accuracy of diameter calculation. More importantly, the objective 42 preferably employs a double telecentric lens design. The characteristic of a telecentric lens is that its principal rays are parallel to the optical axis, meaning that even with minute ups and downs on the wafer surface, the magnification of the image will not change, which is crucial for accurate dimensional measurement.

[0026] Furthermore, to address the specular reflection issue on the silicon wafer surface, the imaging unit 40 is equipped with a coaxial light source 43. Coaxial light is incident perpendicularly to the wafer surface along the objective lens optical axis via a beam splitter. In optical principle, a flat, specular silicon wafer would reflect the perpendicularly incident light back to the lens, forming a bright white background on the image sensor; while the pin mark 60, a pit formed by the physical pressing of a probe, has a complex slope on its bottom and sidewalls, reflecting incident light outside the lens aperture, thus appearing as a dark spot or ring in the image. This "bright-field illumination" technology maximizes the contrast between the pin mark and the background, making the pin mark 60 clearly visible in the image, such as... Figure 2 As shown.

[0027] The control unit 50 is the command center of the entire device, typically consisting of a high-performance industrial computer (IPC) and its real-time control card. It connects to the various subsystems via a high-speed bus, and is responsible not only for motion coordination and data acquisition, but more importantly, for running the core adaptive closed-loop control algorithm of this disclosure. To more clearly illustrate the algorithm's operating mechanism, we divide the device's workflow into "calibration mode" and "production mode."

[0028] In calibration mode, the device performs a series of automated closed-loop adjustment steps. First, the system controls a robotic arm to load a dedicated calibration sample 10 (typically a polished bare silicon wafer with a stable surface) onto the support platform 20. Using a calibration sample instead of a product wafer for adjustment avoids potential damage from trial testing on expensive products. Next, the control unit 50 instructs the Z-axis actuator 32 to drive the probe module 30 downwards. The system precisely captures the instantaneous position of the probe 31 contacting the calibration sample 10 by real-time monitoring of the force feedback or position error signal of the Z-axis motor, denoted as Z0. Subsequently, the Z-axis actuator 32 continues to move downwards, executing the currently stored push-in amount setting (e.g., 0.20 mm). During this process, the hard probe tip pierces the softer silicon wafer surface, breaking the natural oxide layer and leaving a physical probe mark 60. After contact is complete, the probe is lifted.

[0029] Next, the control unit 50 controls the XY platform to move, precisely delivering the newly generated needle mark 60 into the center of the field of view of the imaging unit 40. The high-definition camera 41, in conjunction with the coaxial light source 43, captures a microscopic image of the needle mark. The acquired image data is sent to the image processing module of the control unit 50. This module first preprocesses the image, including grayscale conversion and Gaussian filtering for noise reduction, to remove random noise. Then, an edge detection algorithm (such as the Canny operator or the Sobel operator) is applied to extract the edge pixels of the needle mark 60. Since the actual needle mark may be slightly elliptical or irregular, the algorithm typically uses Hough Transform or Least Squares Fitting to determine the best-fit circle for the needle mark and calculates its equivalent diameter D.

[0030] After obtaining the needle mark diameter D, the control unit 50 initiates the feedback control logic. This logic is not based on a continuous linear function, but rather on a discrete, piecewise look-up table derived from semiconductor process experience to ensure the robustness and safety of the adjustment. The specific piecewise adjustment strategy is as follows: In the first scenario, if the calculated probe mark diameter D is less than 18 micrometers (D < 18 μm), this indicates severely insufficient contact between the probe and the wafer, or that the probe length has shortened due to wear, leading to misjudgment of the Z-axis zero point. In this state, the probe cannot penetrate the oxide layer, resulting in extremely high and unstable contact resistance. Therefore, the system determines this as severely insufficient contact and directly generates a command to significantly adjust the push-in amount setting to the highest digit, such as 0.45 mm, to force effective contact.

[0031] In the second case, if the pin mark diameter D is between 18 micrometers and 20 micrometers (18μm ≤ D < 20μm), it indicates that the contact is in a critical state and the contact resistance may fluctuate. The system determines it as a slight contact deficiency and moderately adjusts the set value of the pushing amount to the second median value, such as 0.30mm, attempting to push the pin mark diameter into the optimal range.

[0032] In the third case, if the pin mark diameter D falls between 20 micrometers and 24 micrometers (20μm ≤ D ≤ 24μm), this is the "standard diameter range" or "golden window" defined in this disclosure. Research on physical mechanisms shows that within this diameter range, the probe has fully pierced the oxide layer, forming a low-impedance Sharvin Resistance contact, and the tunneling effect is stable. At the same time, it has not caused deep dislocations or plastic deformations in the silicon lattice. Therefore, the system determines that the current state is optimal and keeps the current set value of the pushing amount unchanged (for example, maintained at 0.20mm).

[0033] In the fourth case, if the pin mark diameter D is between 24 micrometers and 26 micrometers (24μm < D ≤ 26μm), this usually means that the tip of the probe has become blunt (the tip radius has increased), resulting in an increased contact area under the same pushing amount; or the previous pushing amount setting was too large. The system determines it as a slight contact excess and callback the set value of the pushing amount to the third low value, such as 0.10mm. By reducing the pushing amount to compensate for the effect of the blunt tip, the pin mark is brought back to the safe range.

[0034] In the fifth case, if the pin mark diameter D is greater than 26 micrometers (D > 26μm), this is a danger signal, indicating that the probe may be severely worn into a "mushroom head" shape, or the system has applied destructive pressure. An overly large pin mark not only damages the wafer but also causes abnormal distribution of the test current. The system determines it as a severe contact excess and significantly reduces the set value of the pushing amount to the fourth extremely low value, such as 0.05mm.

[0035] The control unit 50 will repeatedly execute the above process of "detection - measurement - judgment - adjustment" until the pin mark diameter obtained on the calibration sample 10 is stabilized within the standard range of 20 - 24μm. Once the condition is met, the currently optimized pushing amount parameter is locked by the system. Subsequently, the device automatically switches to the production mode. In the production mode, the manipulator removes the calibration sample 10 and batch-loads the product wafers 11 to be tested. At this time, the Z-axis actuator 32 directly calls the locked optimal pushing amount parameter to perform a rapid resistivity scanning test on each product wafer, without performing time-consuming visual feedback adjustment, thus taking into account both high production capacity and high precision.

[0036] To handle extreme situations, the control unit 50 also integrates an anomaly alarm module. If, in calibration mode, the needle mark diameter still fails to enter the standard range after a predetermined number of push-in adjustments (e.g., 3 or 5 times), or if the needle mark remains too large even at extremely low push-in amounts, the system will determine that the probe is physically damaged (e.g., broken or severely deformed) or that the Z-axis mechanism is malfunctioning. In this case, the anomaly alarm module will immediately trigger the equipment to stop and issue an audible and visual alarm through the user interface, prompting engineers to replace the probe card or inspect the equipment, thereby preventing the scrapping of batch products due to blind testing.

[0037] To verify the actual effectiveness of the disclosed device, the inventors conducted a comparative experiment. See [link to experiment]. Figure 3 This figure quantitatively compares the statistical stability of resistivity tests before and after adjustment. Specifically, the bar chart horizontally compares two sets of core data. The left side, "Before Adjustment," represents the resistivity standard deviation obtained using the traditional fixed push-in method, which is 0.060 Ω·m. This indicates that as the probe wears, the contact condition deteriorates, and the test noise increases. The right side, "After Adjustment," represents the resistivity standard deviation obtained using the adaptive adjustment device disclosed in this paper. The value has decreased to 0.037 Ω·m, a reduction of 38.3%. This demonstrates that by locking the probe mark diameter within the 20-24 μm range, the drift of contact resistance can be effectively suppressed, significantly improving the repeatability and reproducibility of the test data.

[0038] Accordingly, see Figure 4 This disclosure also provides a resistivity testing method, performed using the resistivity testing apparatus described in the foregoing embodiments. The method includes the following steps: S401, S402, S403, S404, S405, and S406. S401: Place the calibration sample on the support platform; S402: Drive the probe to contact the surface of the calibration sample to form a needle mark according to the current push-in amount setting; S403: Acquire an image of the needle mark and determine the diameter data of the needle mark; S404: Compare the diameter data with a preset standard diameter range; S405: Generate a correction command based on the comparison result to adjust the push amount setting value until the diameter data of the needle mark falls within the preset standard diameter range; S406: Locks the final confirmed push amount setting for subsequent resistivity testing of the wafer under test.

[0039] In summary, this disclosure, through a sophisticated hardware architecture and intelligent closed-loop control algorithm, transforms the probe contact state, which is difficult to measure directly, into visually quantifiable probe mark geometric features. Based on these features, mechanical motion parameters are dynamically optimized, successfully solving the long-standing problem of uncontrollable probe states in the field of semiconductor resistivity testing. This technical solution not only improves the reliability of metrological data but also effectively extends the lifespan of expensive consumables such as probes, reducing production costs.

[0040] It should be noted that the technical solutions described in this disclosure can be combined arbitrarily as long as they do not conflict.

[0041] The above description is merely a specific embodiment of this disclosure, but the scope of protection of this disclosure is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in this disclosure should be included within the scope of protection of this disclosure. Therefore, the scope of protection of this disclosure should be determined by the scope of the claims.

Claims

1. A resistivity testing device, characterized in that, The device includes: A carrier platform for carrying wafers, the wafers including calibration samples for parameter calibration and product-under-test wafers for performance testing; A probe module includes a probe and an actuator that drives the probe to move in a direction perpendicular to the wafer surface, the actuator being configured to drive the probe to contact the surface of the wafer according to a push-in amount set value; An imaging unit is configured to image the needle marks formed by the probe on the surface of the calibration sample; and The control unit is communicatively connected to the carrier platform, the probe module, and the imaging unit. The control unit is configured to control the imaging unit to acquire an image of the needle mark and determine the diameter data of the needle mark, compare the diameter data with a preset standard diameter range, and generate a correction command based on the comparison result to adjust the push-in amount setting value of the actuator until the diameter data of the needle mark falls within the preset standard diameter range. The final confirmed push-in amount setting value is then locked for subsequent resistivity testing of the wafer under test.

2. The resistivity testing device according to claim 1, characterized in that, The imaging unit includes a microscope objective and an image sensor, wherein the microscope objective has an optical magnification of not less than 200 times.

3. The resistivity testing device according to claim 2, characterized in that, The imaging unit also includes a coaxial illumination system configured to generate light rays parallel to the optical axis of the microscope objective.

4. The resistivity testing device according to claim 1, characterized in that, The actuator is a closed-loop controlled piezoelectric actuator or a voice coil motor.

5. The resistivity testing apparatus according to claim 1, characterized in that, The standard diameter range preset in the control unit is 20 micrometers to 24 micrometers.

6. The resistivity testing apparatus according to claim 1, characterized in that, The control unit adjusts the push-in amount setting value based on the diameter data in the following way: When the diameter data is less than 18 micrometers, the push-in amount setting value is adjusted to the first high-order value; When the diameter data is greater than or equal to 18 micrometers and less than 20 micrometers, the push-in amount setting value is adjusted to the second median value; When the diameter data is greater than 24 micrometers and less than or equal to 26 micrometers, the push-in amount setting value is adjusted to the third lowest value. When the diameter data is greater than 26 micrometers, the push-in amount setting value is adjusted to the fourth lowest value. Wherein, the first high-order value is greater than the second median value, the second median value is greater than the current push amount setting value, the third low-order value is less than the current push amount setting value, and the fourth extremely low value is less than the third low-order value.

7. The resistivity testing apparatus according to claim 6, characterized in that, The first high value is set to 0.45 mm, the second median value is set to 0.30 mm, the third low value is set to 0.10 mm, and the fourth very low value is set to 0.05 mm.

8. The resistivity testing apparatus according to claim 1, characterized in that, The control unit is also equipped with an abnormal alarm module. If the diameter data of the needle mark still does not fall within the preset standard diameter range after a predetermined number of adjustments, or if the diameter data is greater than 26 micrometers and the problem is not improved after adjustment, the abnormal alarm module will trigger the device to stop and issue a probe abnormality prompt.

9. The resistivity testing apparatus according to claim 1, characterized in that, The image processing performed by the control unit to determine the diameter of the needle mark includes edge detection and geometric fitting.

10. A method for testing resistivity, characterized in that, The method is performed using the resistivity testing apparatus according to any one of claims 1 to 9, and includes: The calibration sample is mounted on the support platform; The probe is driven to contact the surface of the calibration sample to form a needle mark based on the current push-in amount setting; Acquire an image of the needle mark and determine the diameter data of the needle mark; Compare the diameter data with a preset standard diameter range; Based on the comparison results, a correction instruction is generated to adjust the push-in amount setting value until the diameter data of the needle mark falls within the preset standard diameter range; The final confirmed push-in amount setting is locked for subsequent resistivity testing of the wafer under test.

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