Film thickness testing device and testing method thereof

Abstract

The invention relates to the technical field of ultrasonic detection, in particular to a film thickness testing device and a testing method.The film thickness testing device comprises a base, a sample table, a probe mounting mechanism, a film thickness testing probe and a control unit, the probe mounting mechanism comprises a Z-direction linear module, a sliding part is connected to the Z-direction linear module, and a self-adaptive adjusting assembly is installed on the sliding part; the self-adaptive adjusting assembly is provided with a shell, a micro-force driving unit and a force sensor, the upper end of the shell is fixedly connected with the sliding part, the micro-force driving unit is installed on the inner wall of the upper end in the shell, and the film thickness testing probe is installed on the lower end face of the micro-force driving unit; the controller drives the film thickness testing probe to be in contact with a tested film on the sample table by controlling the micro-force driving unit; the pressure of the film thickness testing device is actively and adjustably adapted, and the high repeatability precision of the film thickness testing device, the adaptability to different tested objects and the long-term measurement stability are guaranteed.

Description

Technical Field

[0001] This invention relates to the field of ultrasonic testing technology, specifically to a film thickness testing device and its testing method. Background Technology

[0002] As a core non-destructive testing (NDT) device in fields such as semiconductor manufacturing and mechanical component coating inspection, ultrasonic film thickness testing equipment has one of its core functions: achieving efficient transmission of sound waves between the film layer and the substrate through reliable contact between the ultrasonic transducer and the surface of the film layer being tested. This allows for accurate inference of the film thickness based on the sound wave reflection characteristics, providing crucial data support for product quality control. Traditional ultrasonic film thickness testing equipment often uses rigid or manually assisted mechanical structures to drive and adjust the contact process between the transducer and the test object. Common forms include bolt-locked probe supports and cylinder-driven rigid pressing mechanisms. These structures determine the probe contact pressure and orientation through preset mechanical parameters, requiring operators to manually calibrate the relative position of the probe and the test object, and using couplant to fill the contact gap to ensure sound wave transmission. However, in actual testing scenarios, these traditional structures suffer from problems such as the inability to dynamically adapt the contact pressure. Excessive pressure can easily lead to damage to the ultrathin film layer or deformation of the test workpiece, while insufficient pressure makes it difficult to ensure uniform distribution of the couplant, resulting in severe sound wave attenuation and a low signal-to-noise ratio in the echo signal.

[0003] To address the aforementioned issues, existing technologies have proposed several solutions. For example, patent application CN202220969948.8 discloses an integrated ultrasonic thickness gauge. This solution integrates the coupling agent application device and the main body of the ultrasonic thickness gauge into the same housing through an integrated design, automatically extruding the coupling agent through a propulsion component. The film thickness test probe is connected to the housing through a detachable fixing tube, and a drive motor is embedded in the handle to achieve single-handed operation. However, the above solution still has some problems. Relying solely on the spring preload to achieve contact between the probe and the object being measured can easily lead to a fixed and unadjustable contact pressure, making it impossible to optimize for different materials and thicknesses of the object being measured. Furthermore, the spring force decays over time, resulting in decreased contact stability and affecting measurement repeatability. Summary of the Invention

[0004] The purpose of this invention is to provide a film thickness testing device and its testing method to solve the problems of existing film thickness testing devices that rely solely on spring preload to achieve contact between the probe and the test object, resulting in fixed and unadjustable contact pressure, making it impossible to optimize for different materials and thicknesses of the test object, and the spring force decaying over time, leading to decreased contact stability and affecting measurement repeatability.

[0005] To achieve the above objectives, the present invention provides the following technical solution: A film thickness testing device and method thereof include a base, a sample stage, a probe mounting mechanism, a film thickness testing probe, and a control unit. The sample stage, probe mounting mechanism, and control unit are all mounted on the base. The probe mounting mechanism includes a vertically arranged Z-axis linear module. A sliding component is slidably connected to the Z-axis linear module. An adaptive adjustment component is mounted on the sliding component. The adaptive adjustment component has a housing, a micro-force driving unit, and a force sensor. The upper end of the housing is fixedly connected to the sliding component. The micro-force driving unit is mounted on the upper inner wall of the housing. The film thickness testing probe is mounted on the lower end face of the micro-force driving unit. The force sensor is mounted between the micro-force driving unit and the film thickness testing probe. The Z-axis linear module... The module, micro-force drive unit, and force sensor are all electrically connected to the control unit. The controller drives the micro-force drive unit to drive the film thickness test probe to contact the film under test on the sample stage. The above scheme adopts a real-time closed-loop pressure control system composed of micro-force drive unit, force sensor, and control unit, replacing the passive spring mechanism. This allows the contact pressure of the film thickness test probe to be dynamically set and precisely maintained according to different materials and film thicknesses through a program, realizing active and adjustable pressure adaptation. At the same time, the closed-loop feedback mechanism can also compensate for pressure fluctuations caused by any factors in real time, eliminating long-term drift problems caused by fatigue or loosening of mechanical parts, ensuring the high repeatability accuracy of the film thickness test device, its adaptability to different test objects, and its long-term measurement stability.

[0006] Preferably, the micro-force drive unit is a voice coil motor, which includes an outer stator, a moving part connecting shaft, an inner moving part, and a position sensor. The upper end of the outer stator is connected to the upper end of the housing. The moving part connecting shaft is coaxially mounted inside the outer stator. The inner moving part is coaxially slidably connected inside the outer stator. The force sensor is installed between the inner moving part and the film thickness test probe. The position sensor is installed on the end of the moving part connecting shaft away from the film thickness test probe. Both the inner moving part and the position sensor are electrically connected to the control unit. The above scheme uses a voice coil motor with a built-in position sensor as the micro-force drive unit, and works in conjunction with the force sensor and the control unit to form a high dynamic response dual closed-loop control system. This design achieves precise slow positioning and anti-collision control before the film thickness test probe contacts through the position sensor, and achieves real-time pressure feedback and adaptive adjustment after contact through the force sensor. It solves the problem that the contact pressure of traditional devices is fixed and cannot be adjusted, and cannot adapt to diverse workpieces. The electronic closed-loop control eliminates pressure drift caused by mechanical fatigue, ultimately ensuring high precision, high repeatability, high adaptability, and long-term working stability of the film thickness test device during the contact process.

[0007] Preferably, an elastic guide is provided between the inner mover and the outer stator. One end of the elastic guide is connected to the inner wall of the inner mover, and the other end is slidably connected to the mover connecting shaft. The elastic guide is made of spring steel and is wavy. The above scheme achieves pure axial guidance of the inner mover without mechanical contact by using an elastic structure made of wavy spring steel to connect the inner mover and the mover connecting shaft. This design eliminates the inherent friction and clearance of traditional sliding or rolling bearings from a mechanical principle perspective, avoiding the stick-slip effect, motion return error, and distortion of micro-force control signals. It ensures that the driving force of the voice coil motor is accurately and with low loss converted into the axial contact pressure of the film thickness test probe, providing a pure mechanical motion basis for high-precision force closed-loop control. Furthermore, its low-wear characteristics ensure the motion repeatability accuracy, long-term working stability, and maintenance-free reliability of the entire adaptive adjustment mechanism.

[0008] Preferably, a damping alloy gasket is installed between the force sensor and the film thickness test probe. The damping alloy gasket is made of manganese-copper alloy that has undergone aging stabilization treatment. The above scheme designs a high-frequency mechanical vibration isolator by installing an aging-stabilized manganese-copper alloy damping gasket between the force sensor and the film thickness test probe. This design utilizes the high internal loss characteristics of manganese-copper alloy to efficiently absorb and convert the high-frequency vibration energy generated by the film thickness test probe 4 during operation into heat energy along the transmission path. This avoids the upstream transmission of vibration from interfering with the precision force sensor signal and the voice coil motor force closed-loop control system, solving the potential problems of decreased signal-to-noise ratio of force feedback signal and impaired control stability caused by ultrasonic vibration. At the same time, the stabilized material ensures long-term performance consistency, ensuring the ultra-high precision of the force control link of the film thickness test device, the stability of the measurement process, and the long-term reliability and repeatability of the system.

[0009] Preferably, the lower end of the film thickness testing probe is coaxially fitted with a coupling agent management ring. The coupling agent management ring includes an annular body and a flexible sealing skirt. A permeation plate is located at the bottom of the annular body. A liquid storage chamber is located inside both the annular body and the permeation plate. Multiple permeation holes are evenly distributed on the permeation plate, and each permeation hole communicates with the liquid storage chamber. The flexible sealing skirt is fitted onto the outer side of the lower end of the annular body. The flexible sealing skirt is made of rubber, and its lower edge is lower than the bottom surface of the permeation plate. This solution utilizes an annular body coaxially fitted at the lower end of the film thickness testing probe, a built-in liquid storage chamber, a permeation plate with evenly distributed permeation holes at the bottom, and a lower edge lower than the bottom surface of the permeation plate. The flexible rubber sealing skirt of the plate together forms an automatic sealing and capillary permeation system. During operation, the flexible sealing skirt first contacts and adheres to the surface being measured to form a sealed space. Subsequently, the coupling agent in the reservoir cavity permeates evenly through the permeation pores under capillary action. This completely replaces the manual application method that relies on the operator's experience and feel, avoiding uneven coupling agent thickness, air bubbles, and interference with the already stable contact pressure caused by manual application. On the other hand, it ensures a high degree of consistency and reliability of the acoustic coupling conditions for each measurement, ultimately guaranteeing the high quality of the ultrasonic signal of the film thickness testing device, the high repeatability of the measurement results, and the interference-free coordination with the adaptive pressure control process.

[0010] Preferably, a miniature liquid storage tank is installed on the probe mounting mechanism, and the miniature liquid storage tank is connected to the liquid storage chamber via a delivery pipe. The installation position of the miniature liquid storage tank is higher than that of the liquid storage chamber. The above scheme constructs a gravity-driven self-flowing replenishment system by installing the miniature liquid storage tank above the liquid storage chamber and connecting it via a delivery pipe. This design utilizes the static pressure generated by the stable height difference to provide a continuous and stable passive coupling agent supply to the liquid storage chamber, thereby avoiding measurement interruptions caused by coupling agent depletion, the tediousness of frequent manual addition, and the unstable leakage pressure caused by liquid level fluctuations. This ensures the continuity and consistency of the acoustic coupling medium supply. On the other hand, the minimalist passive mechanical structure improves the overall reliability of the system, ultimately ensuring the measurement stability and ease of operation of the film thickness testing device during automated, long-term continuous operation.

[0011] Preferably, a micro-electromagnetic valve is provided between the micro-reservoir and the reservoir. This micro-electromagnetic valve is electrically connected to the control unit. When the contact pressure detected by the force sensor reaches a preset threshold, the control unit controls the solenoid valve to open. This scheme constructs an intelligent couplant supply system triggered by contact pressure by placing the micro-electromagnetic valve on the delivery pipeline between the micro-reservoir and the reservoir and electrically connecting it to the control unit. This design uses the contact pressure fed back in real time by the force sensor as the sole control signal, ensuring that the solenoid valve only opens to supply couplant after the film thickness testing probe has contacted the surface being measured at a stable preset pressure. This eliminates pre-leakage or waste of couplant in non-contact states, preventing contamination of the sample, film thickness testing probe, or measurement environment. Furthermore, it achieves precise synchronization between couplant supply and ideal acoustic coupling conditions, eliminating poor coupling or pressure interference caused by improper supply timing. Ultimately, this design, through active electronic control, ensures a high degree of controllability in the coupling process of the film thickness testing device, consistency of measurement conditions, and a clean and intelligent operation of the entire system.

[0012] The present invention also provides a film thickness testing method using the above-mentioned method, comprising the following steps: S1: Preparation and coarse positioning: Place the sample to be tested on the sample stage; the control unit controls the Z-axis linear module to work and drives the sliding component and the adaptive adjustment component mounted on the sliding component to descend as a whole, so that the film thickness test probe moves to near the sample surface; S2: Adaptive constant pressure contact: The control unit, based on the position sensor, controls the film thickness test probe to advance towards the sample surface at a micro-speed; when the contact pressure detected by the force sensor first reaches the preset contact threshold, the control unit switches to pressure closed-loop control mode, dynamically adjusts the output of the micro-force drive unit, so that the contact pressure reaches and stabilizes at the preset target measurement pressure value; S3: Coupling agent supply and acoustic coupling establishment: After the contact pressure reaches the preset target value, the control unit controls the micro solenoid valve to open, and the coupling agent flows from the micro reservoir into the reservoir of the coupling agent management ring through the delivery pipe; in the sealed space formed by the flexible sealing skirt and the sample surface, the coupling agent seeps out evenly through the permeation holes on the permeation plate to complete the acoustic coupling of the detection interface. S4: Signal Measurement and Data Acquisition: Under the condition that the contact pressure and acoustic coupling state remain stable, the control unit triggers the film thickness test probe to emit ultrasonic signals and receive echo signals to perform film thickness calculation and data recording. S5: Reset and Change Point: After a single-point measurement is completed, the control unit controls the micro solenoid valve to close, then controls the micro-force drive unit to retract, and then controls the Z-axis linear module to lift the film thickness test probe so that it is removed from the sample surface; move the sample or film thickness test probe to the next detection point, and repeat steps S1 to S4 to perform the measurement at the next point.

[0013] Compared with the prior art, the beneficial effects of the present invention are as follows: 1. This invention replaces the passive spring mechanism with a real-time closed-loop pressure control system consisting of a micro-force drive unit, a force sensor, and a control unit. This allows the contact pressure of the film thickness testing probe to be dynamically set and precisely maintained according to different materials and film thicknesses through a program, achieving active and adjustable pressure adaptation. At the same time, the closed-loop feedback mechanism can also compensate for pressure fluctuations caused by any factors in real time, eliminating long-term drift problems caused by fatigue or loosening of mechanical parts, ensuring high repeatability accuracy of the film thickness testing device, adaptability to different test objects, and long-term measurement stability.

[0014] 2. This invention uses a voice coil motor with a built-in position sensor as a micro-force drive unit, and works in conjunction with a force sensor and a control unit to form a dual closed-loop control system with high dynamic response. This solves the problem that the contact pressure of traditional devices is fixed and cannot be adjusted, and cannot be adapted to diverse workpieces. The electronic closed-loop control eliminates pressure drift caused by mechanical fatigue, and ultimately ensures the high precision, high repeatability, high adaptability, and long-term working stability of the film thickness testing device during the contact process.

[0015] 3. This invention constructs an automatic sealing and capillary permeation system through a ring-shaped body coaxially sleeved at the lower end of the probe, a built-in liquid storage chamber, a permeation plate with evenly distributed permeation holes at the bottom, and a flexible rubber sealing skirt with its lower edge lower than the permeation plate. This avoids uneven coupling agent thickness, air bubbles, and interference with the stable contact pressure caused by manual application. On the other hand, it ensures the high consistency and reliability of acoustic coupling conditions for each measurement, ultimately guaranteeing the high quality of the ultrasonic signal of the film thickness testing device, the high repeatability of the measurement results, and the interference-free coordination with the adaptive pressure control process. Attached Figure Description

[0016] Figure 1 This is a schematic diagram of the film thickness testing device of the present invention; Figure 2 This is a schematic diagram of the installation of the Z-axis linear module in the film thickness testing device of the present invention; Figure 3 For the present invention Figure 2 A magnified view of a section at point A in the middle; Figure 4 This is a schematic diagram showing the installation of the film thickness testing probe in the film thickness testing device of the present invention; Figure 5For the present invention Figure 4 Sectional view at point BB; Figure 6 For the present invention Figure 5 Sectional view at CC; Figure 7 This is a flowchart of the film thickness testing method of the present invention.

[0017] In the diagram: 1. Base; 2. Sample stage; 3. Probe mounting mechanism; 301. Z-axis linear module; 302. Sliding component; 4. Film thickness test probe; 5. Control unit; 601. Housing; 602. Force sensor; 7. Voice coil motor; 701. Outer stator; 702. Mover connecting shaft; 703. Inner mover; 704. Position sensor; 705. Elastic guide; 8. Damping alloy gasket; 901. Annular body; 902. Flexible sealing skirt; 903. Permeation plate; 904. Liquid storage chamber; 905. Permeation hole; 906. Miniature liquid storage tank; 907. Miniature solenoid valve. Detailed Implementation

[0018] Please see Figures 1 to 7 This invention provides a film thickness testing device and method, the technical solution of which is as follows: A film thickness testing device and its testing method are described in the following document. Figures 1 to 7The system includes a base 1, a sample stage 2, a probe mounting mechanism 3, a film thickness testing probe 4, and a control unit 5. The sample stage 2, probe mounting mechanism 3, and control unit 5 are all mounted on the base 1. The probe mounting mechanism 3 includes a vertically arranged Z-axis linear module 301. A sliding component 302 is slidably connected to the Z-axis linear module 301. An adaptive adjustment assembly is mounted on the sliding component 302. The adaptive adjustment assembly includes a housing 601, a micro-force drive unit, and a force sensor 602. The upper end of the housing 601 is fixedly connected to the sliding component 302. The micro-force drive unit is mounted on the upper inner wall of the housing 601. The film thickness testing probe 4 is mounted on the lower end face of the micro-force drive unit. The force sensor 602 is mounted between the micro-force drive unit and the film thickness testing probe 4. Between them, the Z-axis linear module 301, the micro-force drive unit, and the force sensor 602 are all electrically connected to the control unit 5. The micro-force drive unit is a voice coil motor 7, which includes an outer stator 701, a mover connecting shaft 702, an inner mover 703, and a position sensor 704. The upper end of the outer stator 701 is connected to the upper end inside the housing 601. The mover connecting shaft 702 is coaxially mounted inside the outer stator 701, and the inner mover 703 is coaxially slidably connected inside the outer stator 701. The force sensor 602 is installed between the inner mover 703 and the film thickness test probe 4. The position sensor 704 is installed on the end of the mover connecting shaft 702 away from the film thickness test probe 4. Both the inner mover 703 and the position sensor 704 are electrically connected to the control unit 5. An elastic guide 705 is provided between the outer stator 701 and the inner stator 703. One end of the elastic guide 705 is connected to the inner wall of the inner mover 703, and the other end is slidably connected to the mover connecting shaft 702. The elastic guide 705 is made of spring steel and is wavy. A damping alloy gasket 8 is installed between the force sensor 602 and the film thickness test probe 4. The damping alloy gasket 8 is made of manganese-copper alloy that has undergone aging stabilization treatment. A coupling agent management ring is coaxially sleeved at the lower end of the film thickness test probe 4. The coupling agent management ring includes an annular body 901 and a flexible sealing skirt 902. A permeation plate 903 is provided at the bottom of the annular body 901. A liquid storage chamber 904 is provided inside the annular body 901 and the permeation plate 903. The permeation plate 903 is evenly distributed with openings. There are multiple permeation holes 905, all of which are connected to the liquid storage chamber 904. A flexible sealing skirt 902 is sleeved on the lower outer side of the annular body 901. The flexible sealing skirt 902 is made of rubber, and its lower edge is lower than the bottom surface of the permeation plate 903. A miniature liquid storage tank 906 is installed on the probe mounting mechanism 3. The miniature liquid storage tank 906 is connected to the liquid storage chamber 904 through a delivery pipe. The installation position of the miniature liquid storage tank 906 is higher than that of the liquid storage chamber 904. A miniature solenoid valve 907 is provided between the miniature liquid storage tank 906 and the liquid storage chamber 904. The miniature solenoid valve 907 is electrically connected to the control unit 5. When the contact pressure detected by the force sensor 602 reaches a preset threshold, the control unit 5 controls the solenoid valve to open.

[0019] When working, please refer to Figures 1 to 7 The operator mounts the vacuum chuck carrying the silicon wafer sample onto the sample stage 2 and starts the device. The control unit 5 executes a self-test procedure: checking the Z-axis linear module 301, voice coil motor 7, all sensors, and the miniature solenoid valve 907 for proper functioning. Simultaneously, the control unit 5 loads preset measurement parameters for the silicon-based silica thin film, including target contact pressure, contact threshold, approach speed of the film thickness test probe 4, and ultrasonic pulse parameters. Sufficient water-based ultrasonic coupling agent has been added to the miniature reservoir 906.

[0020] According to the preset measurement point coordinates, the control unit 5 drives the XY translation mechanism of the sample stage 2 to move the test point on the silicon wafer to directly below the film thickness test probe 4. Then, the control unit 5 activates the Z-axis linear module 301, driving the sliding component 302 and the entire adaptive adjustment assembly mounted on the sliding component 302 to descend rapidly until the lower end of the film thickness test probe 4 stops approximately 1 mm from the silicon wafer surface. This stage is the coarse positioning stage, with position feedback from a high-precision grating ruler, achieving a positioning accuracy of ±1 μm.

[0021] After coarse positioning is completed, control unit 5 switches to fine control mode. Based on feedback from the high-resolution position sensor 704 built into the voice coil motor 7, control unit 5 drives the inner mover 703 of the voice coil motor 7 at an extremely low speed of 10μm per second, driving the film thickness test probe 4 to perform final fine positioning on the silicon wafer surface; this action avoids the problem of damage to the film thickness test probe 4 or the ultrathin film layer caused by high-speed impact.

[0022] When the lower end of the film thickness test probe 4 lightly touches the surface of the silicon wafer, and the force sensor 602 detects that the pressure value exceeds the preset contact threshold for the first time, the control unit 5 immediately records the reading of the voice coil motor 7 position sensor 704 as the mechanical zero point for this measurement. Furthermore, the control unit 5 instantly switches the control mode from position control to pressure closed-loop control. Using the preset target contact pressure as the setpoint and the real-time reading of the force sensor 602 as the feedback value, the control unit 5 dynamically adjusts the current output to the voice coil motor 7 through PID and other control algorithms. The voice coil motor 7 precisely adjusts the output force according to the current command, quickly stabilizing the contact pressure of the film thickness test probe 4 on the silicon wafer within the range of 0.5N ± 0.01N, and maintaining it throughout the process. During this process, the damping alloy gasket 8 absorbs any minor vibrations that the film thickness test probe 4 itself may generate, ensuring the purity and stability of the output signal from the force sensor 602.

[0023] After confirming that the contact pressure has stabilized at the target value, the control unit 5 issues a command to open the micro solenoid valve 907. At this time, the film thickness test probe 4 is stably pressed together. The flexible sealing skirt 902 at the bottom of the coupling agent management ring is elastically deformed due to pressure and tightly adheres to the silicon wafer surface, forming an annular sealed space with a diameter of about 3 mm around the wafer of the film thickness test probe 4. Driven by gravity and the static pressure formed by the height difference between the liquid storage tank and the liquid storage chamber 904, the coupling agent flows into the liquid storage chamber 904 through the delivery pipe. Then, through the evenly distributed permeation holes 905 on the permeation plate 903, under the dominance of capillary force, it slowly and evenly penetrates and fills the sealed space surrounded by the flexible sealing skirt 902, the bottom surface of the permeation plate 903 and the surface of the silicon wafer, forming a uniform thickness, bubble-free coupling liquid film, realizing efficient and stable ultrasonic coupling. The permeation hole 905 structure of the permeation plate 903 is sufficient to prevent the coupling agent from automatically flowing out when not in operation.

[0024] Under the dual stable state of established acoustic coupling and constant contact pressure, control unit 5 triggers film thickness test probe 4. Film thickness test probe 4 emits an ultrasonic pulse with a center frequency of 10MHz towards the lower silica film. The sound wave passes through the coupling layer and is reflected at the upper and lower interfaces of the silica film, generating echoes. At this time, film thickness test probe 4 receives these echo signals and converts them into electrical signals, which are then transmitted to control unit 5. The signal processor in control unit 5 uses time-domain reflectometry or spectrum analysis to accurately calculate the time difference between the emitted pulse and each echo. Combined with the known propagation speed of ultrasound in silica material, control unit 5 calculates the physical thickness of the film in real time. This data, along with process parameters such as pressure and position, is displayed on the operation interface and stored.

[0025] After the single-point measurement data acquisition is completed, the control unit 5 performs a reset operation in sequence: first, it closes the micro solenoid valve 907 to stop the supply of coupling agent; then, it controls the voice coil motor 7 to retract its inner mover 703, so that the contact pressure of the film thickness test probe 4 is reduced to zero; further, it controls the Z-axis linear module 301 to raise the entire adaptive adjustment assembly, so that the film thickness test probe 4 is completely detached from the silicon wafer surface; the flexible sealing skirt 902 scrapes off most of the residual coupling agent when it is raised; the control unit 5 drives the sample stage 2 to move the next preset measurement point to below the film thickness test probe 4, and the system automatically repeats the above steps to measure the next point.

[0026] For silicon wafers that require full-wafer scanning, operators only need to set the measurement point array in the software, and the device can automatically perform the above-mentioned cyclic operation until all points are tested and a thickness distribution map and statistical report are generated.

[0027] The specific embodiment of the present invention has been described in detail above with reference to the accompanying drawings, but the present invention is not limited to the embodiments described above. For those skilled in the art, various changes, modifications, substitutions, and variations made to these embodiments without departing from the principles and ideas of the present invention should still fall within the protection scope of the present invention.

Claims

1. A film thickness testing device, characterized in that, The device includes a base (1), a sample stage (2), a probe mounting mechanism (3), a film thickness testing probe (4), and a control unit (5). The sample stage (2), the probe mounting mechanism (3), and the control unit (5) are all mounted on the base (1). The probe mounting mechanism (3) includes a vertically arranged Z-axis linear module (301). A sliding component (302) is slidably connected to the Z-axis linear module (301). An adaptive adjustment component is mounted on the sliding component (302). The adaptive adjustment component is provided with a housing (6). 01) Micro-force drive unit and force sensor (602), the upper end of the housing (601) is fixedly connected to the sliding component (302), the micro-force drive unit is installed on the upper inner wall inside the housing (601), the film thickness test probe (4) is installed on the lower end surface of the micro-force drive unit, the force sensor (602) is installed between the micro-force drive unit and the film thickness test probe (4), the Z-direction linear module (301), the micro-force drive unit and the force sensor (602) are all electrically connected to the control unit (5).

2. The film thickness testing device according to claim 1, characterized in that: The micro-force drive unit is a voice coil motor (7). The voice coil motor (7) includes an outer stator (701), a mover connecting shaft (702), an inner mover (703), and a position sensor (704). The upper end of the outer stator (701) is connected to the upper end inside the housing (601). The mover connecting shaft (702) is coaxially installed inside the outer stator (701). The inner mover (703) is coaxially slidably connected inside the outer stator (701). The force sensor (602) is installed between the inner mover (703) and the film thickness test probe (4). The position sensor (704) is installed on the end of the mover connecting shaft (702) away from the film thickness test probe (4). Both the inner mover (703) and the position sensor (704) are electrically connected to the control unit (5).

3. The film thickness testing device according to claim 2, characterized in that: An elastic guide (705) is provided between the inner mover (703) and the outer stator (701). One end of the elastic guide (705) is connected to the inner wall of the inner mover (703), and the other end is slidably connected to the mover connecting shaft (702). The elastic guide (705) is made of spring steel and is wavy.

4. The film thickness testing device according to claim 1, characterized in that: A damping alloy gasket (8) is installed between the force sensor (602) and the film thickness test probe (4). The damping alloy gasket (8) is made of manganese-copper alloy that has undergone aging stabilization treatment.

5. The film thickness testing device according to claim 1, characterized in that: The lower end of the film thickness test probe (4) is coaxially fitted with a coupling agent management ring. The coupling agent management ring includes an annular body (901) and a flexible sealing skirt (902). The bottom of the annular body (901) is provided with a permeation plate (903). The interior of the annular body (901) and the permeation plate (903) is provided with a liquid storage chamber (904). Multiple permeation holes (905) are evenly distributed on the permeation plate (903). The multiple permeation holes (905) are all connected to the liquid storage chamber (904). The flexible sealing skirt (902) is fitted on the outer side of the lower end of the annular body (901). The flexible sealing skirt (902) is made of rubber material, and the lower edge of the flexible sealing skirt (902) is lower than the bottom surface of the permeation plate (903).

6. The film thickness testing device according to claim 5, characterized in that: The probe mounting mechanism (3) is equipped with a miniature liquid storage tank (906), which is connected to the liquid storage chamber (904) through a delivery pipe. The installation position of the miniature liquid storage tank (906) is higher than that of the liquid storage chamber (904).

7. The film thickness testing device according to claim 6, characterized in that: A micro solenoid valve (907) is provided between the micro liquid storage tank (906) and the liquid storage chamber (904). The micro solenoid valve (907) is electrically connected to the control unit (5). When the contact pressure detected by the force sensor (602) reaches a preset threshold, the control unit (5) controls the solenoid valve to open.

8. A method for testing film thickness, characterized in that: This method is applied to at least one of the film thickness testing devices according to any one of claims 1 to 7, and the specific method includes: S1: Preparation and coarse positioning: Place the sample to be tested on the sample stage (2); the control unit (5) controls the Z-axis linear module (301) to work and drives the sliding component (302) and the adaptive adjustment component installed on the sliding component (302) to descend as a whole, so that the film thickness test probe (4) moves to a position close to the sample surface. S2: Adaptive constant pressure contact: The control unit (5) controls the film thickness test probe (4) to advance towards the sample surface at a tiny test speed based on the position sensor (704); when the contact pressure detected by the force sensor (602) reaches the preset contact threshold for the first time, the control unit (5) switches to the pressure closed-loop control mode and dynamically adjusts the output of the micro-force drive unit so that the contact pressure reaches and stabilizes at the preset target measurement pressure value; S3: Coupling agent supply and acoustic coupling establishment: After the contact pressure reaches the preset target value, the control unit (5) controls the micro solenoid valve (907) to open, and the coupling agent flows from the micro storage tank (906) into the storage chamber (904) of the coupling agent management ring through the delivery pipe; in the sealed space formed by the flexible sealing skirt (902) and the sample surface, the coupling agent seeps out evenly through the permeation hole (905) on the permeation plate (903) to complete the acoustic coupling of the detection interface; S4: Signal measurement and data acquisition: Under the condition that the contact pressure and acoustic coupling state remain stable, the control unit (5) triggers the film thickness test probe (4) to emit ultrasonic signals and receive echo signals, and performs film thickness calculation and data recording; S5: Reset and Change Point: After the single-point measurement is completed, the control unit (5) controls the micro solenoid valve (907) to close, then controls the micro force drive unit to retract, and then controls the Z-direction linear module (301) to lift the film thickness test probe (4) so ​​that it is removed from the sample surface; move the sample or film thickness test probe (4) to the next detection point, repeat steps S1 to S4, and perform the measurement of the next point.

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