An atomic force microscope capable of thermal property measurements

Abstract

The present application relates to a kind of atomic force microscope capable of thermal property measurement, including laser heater, conversion connecting device, optical microscope camera, sample stage and atomic force detection unit, the atomic force detection unit includes scanning head, laser, four-quadrant laser detector and detection probe, optical microscope camera and atomic force detection unit are set in the upper of sample stage, the fixed platform of the bottom of conversion connecting device is connected on sample stage, the sample to be detected is placed on the sub-sample plate of conversion connecting device, detection probe connects scanning head, for detecting sample;Laser heater is rotatably connected with conversion connecting device, so that laser heater can rotate around sample, it is convenient to carry out laser heating to sample from different directions;Temperature detector is equipped on detection probe, temperature detector includes two electrodes, first electrode is arranged on the needle tip of detection probe, second electrode is arranged above first electrode.

Description

Technical Field

[0001] This invention belongs to the field of atomic force microscopy technology, specifically relating to an atomic force microscope capable of measuring thermal properties. Background Technology

[0002] Atomic force microscopy (AFM) is a nanoscale, high-resolution scanning probe microscope that analyzes the intermolecular forces between the probe tip and the sample surface to scan and test the surface morphology, mechanical, electrical, and magnetic properties of materials. However, for measuring the thermal properties of samples, AFM still relies on the traditional method of heating the sample, i.e., placing a heating device under the sample stage. This method causes the overall sample temperature to rise, making it impossible to test samples with uneven surface temperatures. Furthermore, this method heats only the lower surface of the sample, and for samples with poor thermal conductivity, the temperature of the upper surface will differ significantly from the actual temperature of the heating device, making it impossible to accurately control the thermal properties of the upper surface (i.e., the area detected by the probe tip). Additionally, there is currently no particularly effective method to accurately measure the temperature at the actual sample location detected by the probe tip. Summary of the Invention

[0003] To address the aforementioned technical problems, this invention provides an atomic force microscope capable of measuring thermal properties, comprising a laser heater, a conversion connection device, an optical microscope camera, a sample stage, and an atomic force detection unit. The atomic force detection unit includes a scanning head, a laser, a four-quadrant laser detector, and a detection probe. The optical microscope camera and the atomic force detection unit are positioned above the sample stage. A fixed stage at the bottom of the conversion connection device is connected to the sample stage. The sample to be tested is placed on a sub-sample plate of the conversion connection device. The detection probe is connected to the scanning head for detecting the sample.

[0004] The laser heater is rotated and converted to a switching device, which allows the laser heater to rotate around the sample, facilitating laser heating of the sample from different directions.

[0005] The detection probe is equipped with a temperature detector, which includes two electrodes. The first electrode is located on the tip of the detection probe, and the second electrode is located above the first electrode.

[0006] Atomic force microscopy (AFM) is a relatively mature detection device with various forms, primarily due to the diverse relative placement of its optical microscope camera, atomic force detection unit, and sample stage. As a finished AFM, adding a high-precision heating device requires consideration of its different structural forms, resulting in various structural forms for thermal property detection devices based on the AFM. This hinders the widespread adoption and use of thermal property detection functions. This application designs a conversion connection device that can adapt to various forms of AFM. Simultaneously, the laser heater provides a small heating point, enabling the heating of small areas on the sample to achieve different temperature distributions and precise heating. An electrode-type temperature detector is installed on the detection probe, offering high sensitivity and improving temperature detection accuracy.

[0007] Optionally, the conversion connection device includes a fixed stage, a central rotating shaft and a secondary sample plate from bottom to top. The fixed stage can be snapped onto the original sample stage of the atomic force microscope, so that the conversion connection device can move with the sample stage and cooperate with the optical microscope camera and the atomic force detection unit for detection.

[0008] The bottom end of the central rotating shaft is fixedly connected to the center of the fixed stage, and the top end of the central rotating shaft is rotatably connected to the center of the sub-sample plate, so that the sub-sample plate can rotate around the central rotating shaft.

[0009] A support frame is rotatably connected to the central shaft. The support frame is detachably equipped with a laser heater and several focusing lenses for local heating of the sample on the sub-sample plate.

[0010] Optionally, the fixing platform includes a top fixing plate and a buckle plate on its outer edge. The fixing plate is horizontal, the buckle plate is vertical, the bottom of the buckle plate is provided with a slot, and the height of the buckle plate is not less than the thickness of the sample stage.

[0011] Further optionally, the sub-sample plate is provided with a number of positioning pins evenly distributed, and the fixing plate is provided with a number of positioning holes. The positions of the positioning pins and the positioning holes correspond one-to-one. A positioning baffle is provided inside the positioning hole. The positioning baffle is fixed on the inner wall of the positioning hole and is set horizontally to reduce the inner diameter of the positioning hole and prevent the positioning pin from completely passing through the positioning hole and touching the upper surface of the sample stage.

[0012] Further optionally, the support frame includes a rotating ring, a lower connecting plate, an upper connecting plate, and a bracket assembly. The rotating ring is sleeved on the central rotating shaft. One end of the lower connecting plate is connected to the rotating ring, and the other end is connected to the bottom of the upper connecting plate. The bracket assembly is rotatably connected to the top of the upper connecting plate.

[0013] The lower surface of the lower connecting plate is provided with at least one roller to stabilize the overall support frame when the lower connecting plate rotates horizontally around the central axis.

[0014] Optionally, the support assembly includes a first main support and several secondary supports. The first main support is used to detachably connect to the laser heater, and the secondary supports are used to detachably connect to the focusing lenses. The laser heater is capable of emitting laser beams, and the several focusing lenses are arranged in the path of the laser beams to focus the laser beams.

[0015] Further optionally, the upper connecting plate is square, the top edge of the upper connecting plate is horizontal, and it is provided with a number of recesses. Each recess is embedded with a universal ball bearing. The surface of the universal ball bearing is fixedly connected to the end of the first main bracket or the secondary bracket. The universal ball bearing can rotate in the corresponding recess, but cannot leave the recess, and is used to drive the first main bracket or the secondary bracket to rotate in all directions.

[0016] All secondary supports are located on the same side of the first main support along the top edge of the upper connecting plate.

[0017] Further optionally, the first main support includes a connecting rod and a positioning plate, the end of the connecting rod is connected to a corresponding universal ball bearing, the front end is rotatably connected to the end of the positioning plate, and the front end of the positioning plate is free.

[0018] The laser heater is detachably mounted on the side of the positioning plate facing the sub-support; the lower part of the side of the positioning plate facing the sub-support is provided with several positioning grooves to facilitate positioning of the focusing lens during focusing.

[0019] However, the laser heats up quickly. If it stays in a certain spot for a slightly longer time, the temperature there will continue to rise and exceed the preset detection temperature. Therefore, if the detection probe stays at a certain detection position, the laser cannot stay at that spot or the area including that spot for a long time. After the laser is turned off, the temperature at that detection position will drop rapidly and immediately. This will cause the subsequent detection of that spot or the area including that spot by the detection probe to be at a temperature that is not expected, resulting in detection failure.

[0020] To address the aforementioned issues, the atomic force microscope capable of measuring thermal properties may optionally include a heat-insulating lamp. The heat-insulating lamp is rotatably connected to the top edge of the upper connecting plate via a second main support. The heat-insulating lamp is rotatably connected to the front end of the second main support, for example, via a rotating shaft connection. The end of the second main support is connected to the top edge of the upper connecting plate via a universal joint. Attached Figure Description

[0021] Figure 1 A schematic diagram of the conversion connection device (I);

[0022] Figure 2 This is a schematic diagram (II) of the conversion connection device.

[0023] In the attached diagram, 1-laser heater, 2-positioning groove, 3-positioning plate, 4-connecting rod, 5-universal swivel ball, 6-fixed stage, 7-sub-sample plate, 8-central rotating shaft, 9-focusing lens, 10-fixed plate, 11-positioning pin, 12-positioning hole, 13-recess, 14-rotating ring, 15-lower connecting plate, 16-upper connecting plate, 17-roller, 18-first main support, 19-second main support, 20-sub-support. Detailed Implementation

[0024] This embodiment provides an atomic force microscope capable of measuring thermal properties, such as... Figures 1-2 As shown, it includes a laser heater 1, a conversion connection device, an optical microscope camera, a sample stage, and an atomic force detection unit. The atomic force detection unit includes a scanning head, a laser, a four-quadrant laser detector, and a detection probe. The optical microscope camera and the atomic force detection unit are located above the sample stage. The fixed platform 6 at the bottom of the conversion connection device is connected to the sample stage. The sample to be tested is placed on the sub-sample plate 7 of the conversion connection device. The detection probe is connected to the scanning head for testing the sample.

[0025] The laser heater 1 is rotatably connected to the conversion connection device, which allows the laser heater 1 to rotate around the sample, making it convenient to heat the sample with laser from different directions;

[0026] The detection probe is equipped with a temperature detector, which includes two electrodes. The first electrode is located on the tip of the detection probe, and the second electrode is located above the first electrode.

[0027] Since the conversion connection device of this embodiment is adaptable to various layout forms of atomic force microscopes, the specific structures of the optical microscope camera, sample stage and atomic force detection unit are not shown in the accompanying drawings. Please refer to the existing conventional atomic force microscope structures.

[0028] Optionally, the conversion connection device includes a fixed stage 6, a central rotating shaft 8 and a secondary sample plate 7 from bottom to top. The fixed stage 6 can be snapped onto the original sample stage of the atomic force microscope, so that the conversion connection device can move with the sample stage and cooperate with the optical microscope camera and atomic force detection unit for detection.

[0029] The bottom end of the central rotating shaft 8 is fixedly connected to the center of the fixed stage 6, and the top end of the central rotating shaft 8 is rotatably connected to the center of the sub-sample plate 7, so that the sub-sample plate 7 can rotate around the central rotating shaft 8.

[0030] A support frame is rotatably connected to the central rotating shaft 8. A laser heater 1 and several focusing lenses 9 are detachably mounted on the support frame for local heating of the sample on the sub-sample plate 7.

[0031] Optionally, the fixing platform 6 includes a top fixing plate 10 and a snap-on plate on its outer edge. The fixing plate 10 is horizontal, and the snap-on plate is vertical. The bottom of the snap-on plate has a slot, and the height of the snap-on plate is not less than the thickness of the sample stage. In use, the fixing platform 6 is snapped onto the sample stage, with the lower surface of the fixing plate 10 in close contact with the upper surface of the sample stage, and the slot of the snap-on plate engaging with the bottom edge of the sample stage, so that the conversion connection device is securely connected to the sample stage via the fixing platform 6.

[0032] Optionally, a plurality of positioning pins 11 are evenly arranged on the sub-sample plate 7, and a plurality of positioning holes 12 are provided on the fixing plate 10. The positions of the positioning pins 11 and the positioning holes 12 correspond one-to-one. A positioning baffle is provided inside the positioning hole 12. The positioning baffle is fixed on the inner wall of the positioning hole 12 and is set horizontally to reduce the inner diameter of the positioning hole 12 and prevent the positioning pins 11 from completely passing through the positioning hole 12 and touching the upper surface of the sample stage.

[0033] Because the sub-sample plate 7 can rotate, multiple samples can be placed on it simultaneously. Different areas can be divided according to the number of samples. During testing, the sample to be tested is rotated to a position below the detection probe. When the sub-sample plate 7 has finished rotating and is ready for testing, its position needs to be fixed to prevent it from rotating, facilitating detection by the probe. At this time, all positioning pins 11 or the portion of positioning pins 11 closest to the sample to be tested are pressed downwards and inserted into the corresponding positioning holes 12. The bottom end of the positioning pin 11 abuts against the positioning baffle and does not move further downwards, thus determining the relative position of the sub-sample plate 7 and the fixed stage 6. When the positioning pin 11 is pulled upwards and disengaged from the positioning hole 12, the sub-sample plate 7 can rotate.

[0034] Further optionally, the support frame includes a rotating ring 14, a lower connecting plate 15, an upper connecting plate 16, and a bracket assembly. The rotating ring 14 is sleeved on the central rotating shaft 8. One end of the lower connecting plate 15 is connected to the rotating ring 14, and the other end is connected to the bottom of the upper connecting plate 16. The bracket assembly is rotatably connected to the top of the upper connecting plate 16.

[0035] The lower surface of the lower connecting plate 15 is provided with at least one roller 17, which is used to stabilize the overall support frame when the lower connecting plate 15 rotates horizontally around the central axis 8.

[0036] Optionally, the width of the lower connecting plate 15 near the central pivot 8 is smaller than the width near the outer edge of the fixed platform 6. For example, the lower connecting plate 15 is triangular, with the vertex connected to the rotating ring 14 and the base near the outer edge of the fixed platform 6, making the support for the upper connecting plate 16 more stable. Preferably, the lower connecting plate 15 is perpendicular to the upper connecting plate 16.

[0037] Optionally, the inner wall of the rotating ring 14 is provided with an automatically controllable locking device. When the support frame needs to be fixed in position, the locking device extends out of the inner wall of the rotating ring 14 and locks the central rotating shaft 8. When the support frame needs to rotate, the locking device retracts into the wall of the rotating ring 14, the inner diameter of the rotating ring 14 increases, and the rotating ring 14 can rotate.

[0038] The support frame described in this invention is connected to the central rotating shaft 8 via a rotating ring 14, allowing the laser heater 1 and several focusing lenses 9 mounted on the support assembly to rotate along the outer edge of the fixed stage 6 (or sub-sample plate 7) to adapt to different atomic force microscope layouts. This avoids obstructing the optical microscope camera, sample stage, and atomic force detection unit, while also adjusting the position according to the sample location so that the laser emitted by the laser heater 1 irradiates the area of ​​the sample requiring heating. The rollers 17 not only support the height of the lower connecting plate 15 and the rotating ring 14, providing stable support, but also reduce resistance during rotation.

[0039] Further optionally, the support assembly includes a first main support 18 and several secondary supports 20. The first main support 18 is used to detachably connect the laser heater 1, and the secondary supports 20 are used to detachably connect the focusing lens 9. The laser heater 1 can emit laser rays, and the several focusing lenses 9 are arranged in the path of the laser rays to focus the laser rays. After focusing, a smaller laser heating point is obtained, which is beneficial for precise heating.

[0040] Further optionally, the upper connecting plate 16 is square, the top edge of the upper connecting plate 16 is horizontal, and it is provided with a plurality of recesses 13. Each recess 13 is embedded with a universal ball 5. The surface of the universal ball 5 is fixedly connected to the end of the first main bracket 18 or the secondary bracket 20. The universal ball 5 can rotate in the corresponding recess 13, but cannot leave the recess 13, and is used to drive the first main bracket 18 or the secondary bracket 20 to rotate in various directions.

[0041] All the secondary supports 20 are located on the same side of the first main support 18 along the top edge of the upper connecting plate 16, for example, they are evenly arranged on the same side of the first main support 18.

[0042] Further optionally, the first main support 18 includes a connecting rod 4 and a positioning plate 3. The end of the connecting rod 4 is connected to a corresponding universal ball bearing 5, and the front end is rotatably connected to the end of the positioning plate 3. The front end of the positioning plate 3 is free. The rotatable connection between the connecting rod 4 and the positioning plate 3 is selected from either a shaft connection or a ball bearing connection.

[0043] The laser heater 1 is detachably installed on the side of the positioning plate 3 facing the sub-support 20; the lower part of the side of the positioning plate 3 facing the sub-support 20 is provided with several positioning grooves 2, which facilitates the positioning of the focusing lens 9 during focusing.

[0044] In one specific implementation, the sub-supports 20 are all located on the right side of the first main support 18 and are arranged at equal intervals along the top edge of the upper connecting plate 16. The upper part of the right side of the positioning plate 3 is provided with at least two clips for clamping and installing the laser heater 1. After installation, the laser heater 1 is parallel to the positioning plate 3, with the emitting end of the laser heater 1 facing downwards. The lower part of the right side of the positioning plate 3 is provided with several positioning grooves 2, the number of which is equal to the number of focusing lenses 9. When it is necessary to focus the laser, the sub-supports 20 are rotated so that the left side of the focusing lens 9 abuts against the inside of the positioning groove 2. The dimensions of the clips of the positioning plate 3 and the positioning grooves 2 are designed according to the dimensions of the laser heater 1 and the focusing lens 9, so that after the laser heater 1 and the focusing lens 9 are in place on the positioning plate 3, the laser can be directly focused, avoiding the error caused by manual focusing each time. According to the focusing requirements of each test, a suitable focusing lens 9 is selected and installed on a suitable sub-support 20. The number of focusing lenses 9 used can also be flexibly adjusted. After the laser heater 1 and the focusing lens 9 are placed, a fixing device is provided at the end of the first main support 18 and the secondary support 20, and between the connecting rod 4 and the positioning plate 3, to fix the relative position of the above components. The fixing device can be a conventional fixing device in the art, such as a fixing clip.

[0045] This invention utilizes a laser emitted by a laser heater 1 as a heating source. Several focusing lenses 9 focus the laser to obtain a smaller heating area, facilitating precise heating of a specific location on the sample and achieving different temperature distributions. During detection, the detection probe, under the control of an atomic force microscopy unit, performs the detection using conventional atomic force microscopy. Since atomic force microscopy detects the upper surface of the sample, and laser heating is rapid, it can achieve instantaneous heating. The focused laser follows the tip of the detection probe, irradiating and heating the sample surface in contact with the probe.

[0046] This invention employs a thermocouple-type temperature detector using copper-constantan electrodes. The first electrode is plated on a cantilever beam at the tip of the detection probe (the probe tip is located at the top of the cantilever beam, which connects to the scanning head; this is existing technology in atomic force microscopy and will not be described in detail here). The detected temperature is consistent with the tip temperature. The second electrode is connected to the rear end of the probe tip, where the detected temperature is close to room temperature. By measuring the potential difference between the two ends, the temperature difference can be calculated, thus determining the temperature at the tip. This method offers higher sensitivity, faster detection speed, and improved detection accuracy.

[0047] However, the laser heats up quickly. If it stays in a certain spot for a slightly longer time, the temperature there will continue to rise and exceed the preset detection temperature. Therefore, if the detection probe stays at a certain detection position, the laser cannot stay at that spot or the area including that spot for a long time. After the laser is turned off, the temperature at that detection position will drop rapidly and immediately. This will cause the subsequent detection of that spot or the area including that spot by the detection probe to be at a temperature that is not expected, resulting in detection failure.

[0048] To address the aforementioned issues, the atomic force microscope capable of measuring thermal properties may optionally include a heat-insulating probe lamp. The heat-insulating probe lamp is rotatably connected to the top edge of the upper connecting plate 16 via a second main support 19. The heat-insulating probe lamp is rotatably connected to the front end of the second main support 19, for example, via a rotating shaft connection. The end of the second main support 19 is connected to the top edge of the upper connecting plate 16 via a universal ball bearing 5.

[0049] The heat-insulating lamp, acting as a light source, illuminates the areas of the sample requiring heat preservation. Although the lamp's light temperature is lower than the laser's, the light shines on the area detected by the probe, increasing the heat in the surrounding air and reducing heat loss from the sample to the outside. Simultaneously, the lamp's light also provides heat to compensate for the temperature drop after the sample is removed from the laser. In the short period after removal from the laser, the heat-insulating lamp significantly reduces the temperature drop at the sample's detection location or area, maintaining the temperature optimal for thermal property detection.

[0050] Optionally, the structure of the second main support 19 is the same as that of the first main support 18. The second main support 19 is located on the side of the first main support 18 away from the sub-support 20, or the second main support 19 is located on the side of the last sub-support 20 away from the first main support 18. This allows the focusing lens 9 on the sub-support 20 to rotate into the positioning groove 2 on the positioning plate 3 of the second main support 19 after the laser is turned off, so as to focus the light of the heat preservation lamp, reduce its illumination (effect) range, and increase the temperature of its light.

Claims

1. An atomic force microscope capable of measuring thermal properties, characterized in that, The device includes a laser heater, a conversion connection device, an optical microscope camera, a sample stage, and an atomic force detection unit. The atomic force detection unit includes a scanning head, a laser, a four-quadrant laser detector, and a detection probe. The optical microscope camera and the atomic force detection unit are located above the sample stage. The fixing stage at the bottom of the conversion connection device is snapped onto the sample stage. The sample to be tested is placed on the sub-sample plate of the conversion connection device. The detection probe is connected to the scanning head for testing the sample. The laser heater is rotated and converted to a switching device, which allows the laser heater to rotate around the sample, facilitating laser heating of the sample from different directions. The detection probe is equipped with a temperature detector, which includes two electrodes. The first electrode is located on the tip of the detection probe, and the second electrode is connected to the rear end of the tip of the detection probe. The conversion connection device includes a fixed stage, a central rotating shaft, and a secondary sample plate from bottom to top, so that the conversion connection device can move with the sample stage and cooperate with the optical microscope camera and atomic force detection unit for detection; The bottom end of the central rotating shaft is fixedly connected to the center of the fixed stage, and the top end of the central rotating shaft is rotatably connected to the center of the sub-sample plate, so that the sub-sample plate can rotate around the central rotating shaft. A support frame is rotatably connected to the central rotating shaft. A laser heater and several focusing lenses are detachably mounted on the support frame for local heating of the sample on the sub-sample plate. The support frame includes a rotating ring, a lower connecting plate, an upper connecting plate, and a bracket assembly. The rotating ring is sleeved on the central rotating shaft. One end of the lower connecting plate is connected to the rotating ring, and the other end is connected to the bottom of the upper connecting plate. The bracket assembly is rotatably connected to the top of the upper connecting plate. The support assembly includes a first main support and several secondary supports. The first main support is used to detachably connect the laser heater, and the secondary supports are used to detachably connect the focusing lens. The laser heater can emit laser beams, and the several focusing lenses are arranged in the path of the laser beams to focus the laser beams. The top edge of the upper connecting plate is horizontal and has several recesses. Each recess is embedded with a universal ball bearing. The surface of the universal ball bearing is fixedly connected to the end of the first main bracket or the secondary bracket. The universal ball bearing can rotate in the corresponding recess, but cannot leave the recess, and is used to drive the first main bracket or the secondary bracket to rotate in all directions.

2. The atomic force microscope capable of measuring thermal properties according to claim 1, characterized in that, The fixed platform includes a top fixed plate and a buckle plate on its outer edge. The fixed plate is horizontal and the buckle plate is vertical. The bottom of the buckle plate is provided with a slot and the height of the buckle plate is not less than the thickness of the sample stage.

3. The atomic force microscope capable of measuring thermal properties according to claim 1, characterized in that, The sub-sample plate is evenly provided with several positioning pins, and the fixing plate is provided with several positioning holes. The positions of the positioning pins and the positioning holes correspond one-to-one. A positioning baffle is provided inside the positioning hole. The positioning baffle is fixed on the inner wall of the positioning hole and is set horizontally to reduce the inner diameter of the positioning hole and prevent the positioning pin from completely passing through the positioning hole and touching the upper surface of the sample stage.

4. The atomic force microscope capable of measuring thermal properties according to claim 1, characterized in that, The lower surface of the lower connecting plate is provided with at least one roller, which is used to stabilize the overall support frame when the lower connecting plate rotates horizontally around the central axis.

5. The atomic force microscope capable of measuring thermal properties according to claim 1, characterized in that, The upper connecting plate is square. All secondary supports are located on the same side of the first main support along the top edge of the upper connecting plate.

6. The atomic force microscope capable of measuring thermal properties according to claim 5, characterized in that, The first main support includes a connecting rod and a positioning plate. The end of the connecting rod is connected to a corresponding universal ball bearing, and the front end is rotatably connected to the end of the positioning plate. The front end of the positioning plate is free. The laser heater is detachably mounted on the side of the positioning plate facing the sub-support; the lower part of the side of the positioning plate facing the sub-support is provided with several positioning grooves to facilitate positioning of the focusing lens during focusing.

7. The atomic force microscope capable of measuring thermal properties according to claim 6, characterized in that, The atomic force microscope capable of measuring thermal properties also includes a heat-insulating lamp, which is rotatably connected to the top edge of the upper connecting plate via a second main support. The heat-insulating lamp is rotatably connected to the front end of the second main support, and the end of the second main support is connected to the top edge of the upper connecting plate via a universal joint.

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