A chemical mechanical polishing detection device and detection method thereof

Abstract

The invention discloses a chemical mechanical polishing detection device and a detection method thereof, which relate to the technical field of chemical mechanical polishing, and comprise a workpiece clamping portion for clamping a transparent workpiece, a driving portion for driving a polishing pad to rotate, and an image acquisition portion for acquiring an image of the surface morphology of the polishing pad. A pressure sensor is arranged on the workpiece holding portion, and the pressure sensor is used to measure the normal pressure generated by the normal displacement of the workpiece under the action of the polishing pressure. The invention utilizes an image acquisition device to capture the surface morphology of the polishing pad between polishing interfaces in real time, and in combination with the monitoring of the stress condition of the polishing interface, the change of the friction coefficient of the polishing pad surface can be analyzed and obtained, and the relationship between the change of the friction coefficient and parameters such as the change of abrasive particle distribution and the change of wear, thereby solving the technical problem that the distribution of abrasive particles at the polishing interface, the morphology of the polishing pad and the interface friction characteristics cannot be associated.

Description

Technical Field

[0001] The present invention relates to the technical field of chemical mechanical polishing, and in particular to a chemical mechanical polishing detection device and a detection method thereof. Background Art

[0002] Ultra-precision machining is an important direction in the field of mechanical manufacturing, and chemical mechanical polishing is the most commonly used method in ultra-precision machining. The distribution of abrasive particles and the friction characteristics of the polishing interface during chemical mechanical polishing have always been the focus of attention in this field.

[0003] The presence and distribution of abrasive particles in the chemical mechanical polishing interface directly affect the surface quality of the polished part, and have an impact on the surface scratches, rough morphology, performance consistency and material removal rate of the workpiece. However, current technology cannot directly detect the presence and distribution of abrasive particles in the polishing interface, and the chemical mechanical polishing process is mostly formulated based on empirical estimates. The general process is: select the type and size of abrasive particles based on the type of polishing workpiece and polishing liquid, and then estimate the number of abrasive particles required based on the requirements of rough and fine polishing. This experience-based process is somewhat blind and lacks specific theoretical guidance.

[0004] Furthermore, the essence of chemical mechanical polishing is a three-body interface tribology problem. Friction is one of the specific quantitative indicators of interface friction characteristics, which directly reflects the material removal rate characteristics in the chemical mechanical polishing interface. Therefore, the relationship between the friction of the polishing interface, the friction coefficient of the polishing surface and the size, coarseness, distribution state and wear state of the abrasive particles is obtained, which has important guiding significance for making a more standardized and reasonable polishing process. However, some existing polishing test machines can only measure the friction during the polishing process or the surface stiffness of the polishing pad in a non-working state, such as the invention patent with application number "201810737394.7" and the name "Polishing Friction Measurement Device and Measurement Method", and the invention patent with application number "202010291933.6" and the name "A Polishing Pad Micro-Contact State Measurement Device and Its Use Method", but both of them failed to analyze the relationship between the friction coefficient of the polishing interface and the distribution of abrasive particles and the morphology of the polishing pad, and cannot play a good guiding role in making a more reasonable polishing process. Summary of the invention

[0005] The purpose of the present invention is to provide a chemical mechanical polishing detection device and a detection method thereof to solve the problems existing in the prior art, and to correlate the abrasive distribution on the polishing interface, the polishing pad morphology and the interface friction characteristics, thereby laying a reliable foundation for further clarifying the essence of polishing, optimizing the polishing process, improving polishing efficiency and reducing polishing costs.

[0006] To achieve the above object, the present invention provides the following solution: a chemical mechanical polishing detection device, comprising a workpiece clamping portion for clamping a transparent workpiece, the workpiece holding portion is provided with a pressure sensor, the pressure sensor is used to measure the normal pressure generated by the normal displacement of the workpiece under the action of polishing pressure; the workpiece holding portion is also provided with a shooting area;

[0007] Also includes a driving unit for driving the polishing pad to rotate;

[0008] It also includes an image acquisition unit for acquiring an image of the surface morphology of the polishing pad, and the image acquisition unit acquires an image of the surface morphology of the polishing pad through the shooting area.

[0009] Preferably, the area of ​​the shooting region is larger than the area of ​​the polishing pad.

[0010] Preferably, two pressure sensors are provided and are respectively located at two ends of a diagonal line after the workpiece is installed.

[0011] Preferably, a torque sensor for measuring torque is provided on the driving shaft of the driving unit.

[0012] Preferably, the workpiece clamping portion is provided with a clamping groove for clamping the workpiece, and the pressure sensor is provided at the clamping groove; the clamping groove is also provided with a plurality of bolt holes, and fixing bolts are used to fix the workpiece in the clamping groove.

[0013] Preferably, the workpiece clamping portion is fixed on a sliding block, the sliding block is slidably disposed on a fixed bracket, and the fixed bracket is slidably disposed on a base.

[0014] Preferably, a first screw is provided on the fixed bracket, a first nut is connected to the first screw, and the first nut is fixedly connected to the slider; a first sliding groove is also provided on the fixed bracket, and a first protrusion that slidably cooperates with the first sliding groove is provided on the slider.

[0015] Preferably, a second lead screw is provided on the base, a second lead screw is connected to a second nut, and the second nut is fixedly connected to the fixed bracket; a second slide groove is also provided on the base, and a second protrusion cooperating with the second slide groove is also provided on the fixed bracket.

[0016] Preferably, the image acquisition unit is slidably disposed on a graphics acquisition bracket, the image acquisition unit comprises an industrial camera, the objective lens of the industrial camera faces the shooting area, and the industrial camera is also provided with a focus adjustment knob for adjusting the focal length.

[0017] The present invention also provides a detection method of a chemical mechanical polishing detection device, comprising the following steps:

[0018] 1) Fix the polishing pad on the polishing disc;

[0019] 2) Place the workpiece into the clamping groove and tighten it with fixing bolts, and adjust the position of the workpiece clamping part so that the workpiece surface is close to the polishing pad;

[0020] 3) Adjust the position of the industrial camera so that the objective lens faces the polishing pad, and then adjust the focal length of the objective lens so that the industrial camera can capture a clear image of the surface topography of the polishing pad;

[0021] 4) Electrically connect the industrial camera, torque sensor, and pressure sensor to the monitoring system;

[0022] 5) Turn on the drive unit to polish the workpiece.

[0023] Compared with the prior art, the present invention has achieved the following technical effects:

[0024] 1. The present invention uses an image acquisition device to capture the surface morphology of the polishing pad at the polishing interface in real time, which can fully understand the distribution change of abrasive particles and their wear change during the polishing process. Combined with the monitoring of the force condition of the polishing interface, the present invention can analyze the change of the friction coefficient of the polishing pad surface, and the relationship between the change of the friction coefficient and the parameters such as the distribution change of abrasive particles and the wear change, thereby solving the technical problem of being unable to associate the distribution of abrasive particles at the polishing interface, the morphology of the polishing pad and the friction characteristics of the interface, and laying a reliable foundation for further clarifying the essence of polishing, optimizing the polishing process, improving the polishing efficiency and reducing the polishing cost;

[0025] 2. In the present invention, the workpiece is made of a transparent material, and a transparent shooting area is provided on the workpiece clamping portion, which provides a good structural basis for the image acquisition device to collect the surface morphology of the polishing pad;

[0026] 3. The present invention adopts a ball screw structure for both horizontal and vertical adjustment of the workpiece, which has high adjustment accuracy and a large adjustment range for the positive pressure of the workpiece, making it easy to study the wear and distribution of the grinding particles under various pressures and torques, making the test results more substantial; and the ball screw structure has low friction resistance and is very convenient to adjust. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative labor.

[0028] Figure 1 It is a structural schematic diagram of the present invention;

[0029] Figure 2 for Figure 1 The main view of

[0030] Figure 3 It is a structural schematic diagram of the workpiece clamping part;

[0031] Figure 4 for Figure 3 A top view of

[0032] Figure 5 It is the cross-sectional view of AA;

[0033] Figure 6 It is a schematic diagram of the connection structure of the slider, the fixed bracket and the base in the present invention;

[0034] Among them, 1. workpiece; 2. workpiece clamping part; 3. driving part; 4. image acquisition part; 5. pressure sensor; 6. shooting window; 7. polishing pad; 8. torque sensor; 9. servo motor; 10. clamping groove; 11. fixed cavity; 12. slider; 13. fixed bracket; 14. base; 15. first lead screw; 16. slider adjustment knob; 17. first slide groove; 18. first protrusion; 19. second lead screw; 20. fixed bracket adjustment knob; 21. second slide groove; 22. second protrusion; 23. image acquisition bracket; 24. industrial camera; 25. objective lens; 26. focal length adjustment knob. DETAILED DESCRIPTION

[0035] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0036] The purpose of the present invention is to provide a chemical mechanical polishing detection device and a detection method thereof to solve the problems existing in the prior art, and to correlate the abrasive distribution on the polishing interface, the polishing pad morphology and the interface friction characteristics, thereby laying a reliable foundation for further clarifying the essence of polishing, optimizing the polishing process, improving polishing efficiency and reducing polishing costs.

[0037] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the present invention is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0038] Embodiment 1:

[0039] The present embodiment provides a chemical mechanical polishing detection device, including a workpiece clamping portion 2 for clamping a transparent workpiece 1, a driving portion 3 for driving a polishing pad 7 to rotate, and an image acquisition portion 4 for acquiring an image of the surface morphology of the polishing pad 7. A pressure sensor 5 is provided on the workpiece 1 holding portion, and the pressure sensor 5 is used to measure the normal pressure generated by the normal displacement of the workpiece 1 under the action of the polishing pressure. A shooting area is provided on the workpiece 1 holding portion, and the image acquisition portion 4 acquires an image of the surface morphology of the polishing pad 7 through the shooting area.

[0040] During the inspection, the workpiece 1 is first fixed on the workpiece clamping part 2, and the workpiece 1 is aligned with the shooting area. Then, the workpiece 1 is moved to the surface of the polishing pad 7, and the driving part 3 drives the polishing pad 7 to polish the surface of the workpiece 1. The image acquisition part 4 is aligned with the polishing pad 7, and the image of the surface morphology of the polishing pad 7 is acquired through the shooting area and the workpiece 1. During the inspection, the workpiece 1 will produce a slight lateral deformation under the pressure of the polishing pad 7. This slight deformation will cause the measured value of the pressure sensor 5 to change, thereby obtaining the normal pressure on the workpiece 1, and then according to the stiffness and deformation coefficient of the workpiece 1, the positive pressure value Fn on the workpiece 1 is calculated. The driving part The torque M output during the actual rotation process can be determined by conventional means in the prior art, and M=f×L, f=Fn×μ (f is the friction force of the polishing interface, L is the equivalent torque of the force applied by the polishing pad 7, and μ is the friction coefficient of the polishing pad 7 interface), and M, L, and Fn are all known values ​​obtained by calculation or measurement, so μ can be calculated; combined with the acquisition of the surface morphology of the polishing pad 7 by the image acquisition unit 4, and by changing the size, shape, number, distribution state and other parameters of the abrasive particles on the surface of the polishing pad 7 one by one, multiple detection experiments are performed to obtain the relationship between the friction coefficient of the friction interface and various parameters of the abrasive particles on the surface of the polishing pad 7.

[0041] Therefore, this embodiment uses the image acquisition device to capture the surface morphology of the polishing pad 7 at the polishing interface in real time, so as to fully understand the distribution changes of the abrasive particles and their wear changes during the polishing process. Combined with the monitoring of the force conditions of the polishing interface, it is possible to analyze the changes in the surface friction coefficient of the polishing pad 7, and the relationship between the changes in the friction coefficient and parameters such as the distribution changes of the abrasive particles and the wear changes. This solves the technical problem of being unable to correlate the distribution of abrasive particles at the polishing interface, the morphology of the polishing pad 7 and the interface friction characteristics, and lays a solid foundation for further clarifying the essence of polishing, optimizing the polishing process, improving polishing efficiency and reducing polishing costs.

[0042] In order to ensure that the image acquisition unit 4 can acquire the overall surface morphology of the polishing pad 7, the area of ​​the shooting region in this embodiment is larger than the area of ​​the polishing pad 7; specifically, in this embodiment, the shooting region is a shooting window 6 opened on the workpiece clamping portion 2, and after the workpiece 1 is fixed in the clamping portion, it is located below the shooting window 6 and adjacent to the shooting window 6, and after the polishing pad 7 is fixed, it is located below the workpiece 1, and the image acquisition unit 4 is located above the workpiece clamping portion 2 and directly opposite to the shooting window 6 and the polishing pad 7, so that the surface morphology of the polishing pad 7 can be acquired in real time.

[0043] In order to reduce the error caused by the uneven deformation of the workpiece 1, two pressure sensors 5 are provided in this embodiment, and they are respectively located at the two ends of the diagonal after the workpiece 1 is installed, and the average value of the two is taken to calculate the normal pressure of the polishing interface.

[0044] In order to facilitate the real-time collection of the torque value of the polishing interface, a torque sensor 8 for measuring torque is provided on the driving shaft of the driving unit 3 in this embodiment. The driving unit 3 can specifically be a servo motor 9, which drives the polishing plate used to fix the polishing pad 7 to rotate; and the transmission method between the servo motor 9 and the polishing plate can be connected and transmitted through a coupling, or through a worm gear connection. The specific method is not specifically limited in this embodiment.

[0045] Furthermore, in the present embodiment, a clamping groove 10 for clamping the workpiece 1 is provided on the workpiece clamping portion 2, and two clamping grooves 10 are relatively arranged, and the side of each clamping groove 10 is connected to a fixed cavity 11 for placing the pressure sensor 5; in the present embodiment, a fixing bolt is used to fix the workpiece 1, and a plurality of bolt holes are provided at the clamping groove 10, and the fixing bolt fixes the workpiece 1 in the clamping groove 10 through the bolt.

[0046] In order to facilitate the movement of the fixed workpiece 1 and put it in a suitable position, in this embodiment, the workpiece clamping part 2 is fixed on a slider 12, and the slider 12 is vertically slidably arranged on a fixed bracket 13, and the fixed bracket 13 is horizontally slidably arranged on a base 14; a first screw 15 is arranged on the fixed bracket 13, and a first nut is connected to the first screw 15, which is not shown in the figure. The first nut is fixedly connected to the slider 12, and a slider adjustment knob 16 is also arranged at the end of the first screw 15. The first screw 15 is rotated by rotating the slider adjustment knob 16, thereby driving the slider 12 to move on the first screw 15, so as to adjust the position of the workpiece 1 in the vertical direction. In order to ensure the stability of the movement of the slider 12, a first screw 15 is also arranged on the fixed bracket 13. A first slide groove 17 is provided, and a first protrusion 18 that slidably cooperates with the first slide groove 17 is provided on the slider 12; similarly, a second screw 19 is provided on the base 14 of this embodiment, and a second nut is connected to the second screw 19, which is not shown in the figure. The second nut is fixedly connected to the bottom of the fixed bracket 13, and a fixed bracket adjusting knob 20 is also provided at the end of the second screw 19. The second screw 19 is rotated by rotating the fixed bracket adjusting knob 20, thereby driving the fixed bracket 13 to move on the second screw 19, thereby realizing the horizontal position adjustment of the workpiece 1; in order to ensure the stability of the movement of the fixed bracket 13, a second slide groove 21 is also provided on the base 14, and a second protrusion 22 that cooperates with the second slide groove 21 is also provided on the fixed bracket 13.

[0047] In this embodiment, the horizontal and vertical adjustments of the workpiece 1 are both made with a ball screw structure, which has high adjustment accuracy and a large adjustment range for the positive pressure of the workpiece 1, making it easy to study the wear and distribution of the grinding particles under various pressures and torques, thereby making the detection results more substantial; and the ball screw structure has low friction resistance and is very convenient to adjust.

[0048] In order to facilitate the adjustment of the position of the image acquisition unit 4 so that the image acquisition unit 4 can capture clear images, the image acquisition unit 4 in this embodiment is slidably set on the graphic acquisition bracket, and the image acquisition unit 4 and the image acquisition bracket 23 can also be matched through a ball screw structure or through a gear rack meshing method. The specific sliding structure can be implemented by those skilled in the art based on the existing technology and will not be described in detail here.

[0049] The image acquisition unit 4 includes an industrial camera 24 , the objective lens 25 of the industrial camera 24 faces the shooting area, and the industrial camera 24 is also provided with a focus adjustment knob 26 for adjusting the focus.

[0050] In this embodiment, the driving unit 3, the image acquisition bracket and its base 14 can be fixed on the work platform, and in order to reduce the movement of each component, in the vertical direction, the objective lens 25 of the industrial camera 24 should be aligned with the polishing disk, and the position of the driving unit 3 should be in the horizontal movement direction of the fixed frame.

[0051] In order to accurately adjust the position of the workpiece 1 , the base 14 , the fixing bracket 13 and the image acquisition bracket 23 are all provided with scales.

[0052] Those skilled in the art should understand that the present embodiment should also include a monitoring system, in which the industrial camera 24, the torque sensor 8, and the pressure sensor 5 are all electrically connected to the monitoring system to analyze values ​​such as torque and pressure in real time and store the captured images.

[0053] Embodiment 2:

[0054] This embodiment provides a detection method of a chemical mechanical polishing detection device, comprising the following steps:

[0055] 1) Fix the polishing pad 7 on the polishing plate;

[0056] 2) Place the workpiece 1 into the clamping groove 10 and fix it with fixing bolts, and adjust the position of the workpiece clamping portion 2 so that the surface of the workpiece 1 is in close contact with the polishing pad 7;

[0057] 3) adjusting the position of the industrial camera 24 so that the objective lens 25 faces the polishing pad 7, and then adjusting the focal length of the objective lens 25 so that the industrial camera 24 can capture a clear image of the surface morphology of the polishing pad 7;

[0058] 4) Electrically connecting the industrial camera 24, the torque sensor 8, and the pressure sensor 5 to the monitoring system;

[0059] 5) Turn on the driving unit 3 to polish the workpiece 1.

[0060] After one polishing is completed, the friction coefficient of the polishing interface and the changes in its torque and pressure are calculated and summarized; then the workpiece 1 is replaced, and the number, size, material, distribution and other parameters of the abrasive particles on the polishing pad 7 are distributed and changed, and the above steps are repeated. Finally, the relationship between the friction coefficient of the polishing interface and the number, size, material and distribution of the abrasive particles is summarized and analyzed.

[0061] Adaptive changes made according to actual needs are all within the protection scope of the present invention.

[0062] It should be noted that it is obvious to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the present invention can be implemented in other specific forms without departing from the spirit or essential features of the present invention. Therefore, from any point of view, the embodiments should be regarded as exemplary and non-restrictive, and the scope of the present invention is defined by the appended claims rather than the above description, and it is intended that all changes falling within the meaning and scope of the equivalent elements of the claims are included in the present invention. Any reference numerals in the claims should not be regarded as limiting the claims involved.

Claims

1. A chemical mechanical polishing detection device, characterized in that: The invention comprises a workpiece clamping part for clamping a transparent workpiece, wherein a pressure sensor is arranged on the workpiece clamping part, and the pressure sensor is used to measure the normal pressure generated by the normal displacement of the workpiece under the action of the polishing pressure; the workpiece clamping part is also provided with a shooting area; the workpiece clamping part also comprises a driving part for driving the polishing pad to rotate; and the image acquisition part is also provided for acquiring an image of the surface morphology of the polishing pad, and the image acquisition part acquires an image of the surface morphology of the polishing pad through the shooting area; The area of ​​the shooting region is larger than the area of ​​the polishing pad; The shooting area is a shooting window opened on the workpiece clamping part. After the workpiece is fixed on the clamping part, it is located below and close to the shooting window. After the polishing pad is fixed, it is located below the workpiece. The image acquisition part is located above the workpiece clamping part and is opposite to the shooting window and the polishing pad, so that the surface morphology of the polishing pad can be acquired in real time.

2. The chemical mechanical polishing detection device according to claim 1, characterized in that: There are two pressure sensors, which are respectively located at two ends of the diagonal line after the workpiece is installed.

3. The chemical mechanical polishing detection device according to claim 1 or 2, characterized in that: A torque sensor for measuring torque is arranged on the driving shaft of the driving unit.

4. The chemical mechanical polishing detection device according to claim 3, characterized in that: The workpiece clamping portion is provided with a clamping groove for clamping the workpiece, and the pressure sensor is arranged at the clamping groove; the clamping groove is also provided with a plurality of bolt holes, and fixing bolts are used to fix the workpiece in the clamping groove.

5. The chemical mechanical polishing detection device according to claim 3, characterized in that: The workpiece clamping portion is fixed on a sliding block, the sliding block is slidably arranged on a fixed bracket, and the fixed bracket is slidably arranged on a base.

6. The chemical mechanical polishing detection device according to claim 5, characterized in that: The fixed bracket is provided with a first screw, the first screw is connected with a first nut, and the first nut is fixedly connected to the slider; the fixed bracket is also provided with a first sliding groove, and the slider is provided with a first protrusion that slidably cooperates with the first sliding groove.

7. The chemical mechanical polishing detection device according to claim 5, characterized in that: The base is provided with a second lead screw, the second lead screw is connected with a second nut, and the second nut is fixedly connected to the fixed bracket; the base is also provided with a second slide groove, and the fixed bracket is also provided with a second protrusion that cooperates with the second slide groove.

8. The chemical mechanical polishing detection device according to claim 3, characterized in that: The image acquisition unit is slidably arranged on the graphic acquisition bracket, and the image acquisition unit comprises an industrial camera, the objective lens of the industrial camera faces the shooting area, and the industrial camera is also provided with a focus adjustment knob for adjusting the focus.

9. A chemical mechanical polishing detection method implemented by the chemical mechanical polishing detection device according to any one of claims 1 to 8, characterized in that: The following steps are involved: 1) Fix the polishing pad on the polishing disc; 2) Place the workpiece into the clamping groove and tighten it with fixing bolts, and adjust the position of the workpiece clamping part so that the workpiece surface is close to the polishing pad; 3) Adjust the position of the industrial camera so that the objective lens faces the polishing pad, and then adjust the focal length of the objective lens so that the industrial camera can capture a clear image of the surface topography of the polishing pad; 4) Electrically connect the industrial camera, torque sensor, and pressure sensor to the monitoring system; 5) Turn on the drive unit to polish the workpiece.

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