An optical film thickness measuring device with anti-interference function

Abstract

The present invention relates to the field of thickness measurement technology, and discloses an optical film thickness measurement device with an anti-interference function, comprising a test box and a test table, a connecting line arranged on one side of the test box, an integrated probe arranged on one side of the test table, the integrated probe and the test box being connected by the connecting line, the device also comprising a sample table arranged on the test table, a drive unit arranged inside the test table, a rotation synchronization device arranged on the sample table, and an optical path stabilization compensation module; the drive unit comprises a helical motion component and an anti-interference component; the helical motion component is used to drive the sample table to move horizontally while rotating. By providing the helical motion component, the laser emission point at the bottom of the integrated probe forms an Archimedean spiral trajectory on the optical film, thereby achieving equidistant radial coverage of the measurement, completing full-area scanning, shortening the overall measurement time, reducing the influence of environmental variables, and having the characteristics of fast traversal and real-time feedback.

Description

Technical Field

[0001] The present invention relates to the technical field of thickness measurement, and in particular to an optical film thickness measuring device with an anti-interference function. Background Art

[0002] Optical thin films, as a type of optical medium material composed of thin, finely layered media, cleverly change the transmission characteristics of light waves through the propagation and manipulation of light beams between interfaces. They can not only achieve surface roughening and significantly improve the surface roughness, thereby optimizing the overall performance of optical components, but are also an indispensable key means to achieve specific design goals. They are widely used in optical devices, semiconductors, display panels and other fields, and their thickness uniformity directly affects device performance. Traditional optical film thickness measurement methods (such as ellipsometry and white light interferometry) are mostly based on single-point measurement, which makes it difficult to fully characterize the spatial thickness distribution of the film and is easily affected by local defects (such as dust and scratches). Although the existing technology achieves two-dimensional scanning (such as grid point measurement) through a mechanical platform, it has the following defects:

[0003] 1. Insufficient uniformity coverage: The grid points are distributed discretely and cannot continuously reflect the radial / circumferential thickness gradient (such as the center-edge thickness difference caused by the coating process);

[0004] 2. Inefficiency: Scanning point by point takes a long time and cannot meet the rapid detection needs of the production line.

[0005] To address these issues, continuous path scanning, such as the Archimedean spiral trajectory, has been introduced. Its equidistant radial distribution allows for uniform coverage of the entire film surface, and combined with dynamic data fitting, statistical accuracy can be improved. Furthermore, spiral scanning relies on a precision transmission mechanism (such as a ball screw coupled with a stepper motor), which is susceptible to mechanical vibration and friction at low speeds, leading to trajectory deviation. Therefore, an optical film thickness measurement device with anti-interference capabilities, low vibration, and high uniformity is urgently needed to meet the high-precision and high-efficiency industrial demands. Summary of the Invention

[0006] In view of the problems in the prior art that when measuring the thickness of optical thin films, uniformity coverage is insufficient and measurement efficiency is low, an optical film thickness measurement device with anti-interference function is proposed.

[0007] Its purpose is: through the setting of the spiral motion component, the trajectory of the laser emission point at the bottom of the integrated probe on the optical diaphragm is an Archimedean spiral, which can achieve equidistant radial coverage of the measurement, evenly distribute the measuring points in the two-dimensional plane, cover the entire area from the center to the edge, complete the full-area scan, shorten the overall measurement time, and reduce the influence of environmental variables (such as temperature and humidity).

[0008] The technical solution of the present invention is an optical film thickness measurement device with anti-interference function, comprising a test box and a test table, a connecting line arranged on one side of the test box, an integrated probe arranged on one side of the test table, the integrated probe and the test box being connected by a connecting line, a sample table arranged on the test table, a drive unit arranged inside the test table, a rotation synchronization device arranged on the sample table, and an optical path stabilization compensation module;

[0009] The driving unit includes a helical motion component and an anti-interference component;

[0010] The helical motion component is used to drive the sample stage to move horizontally while rotating;

[0011] The anti-interference component is used to reduce the vibration of the optical diaphragm on the sample stage caused by the slight mechanical vibration generated when the spiral motion component drives the sample stage to move, thereby affecting the measurement results;

[0012] The rotation synchronization device is used to synchronize the sample stage rotation angle signal with the interferometer sampling trigger;

[0013] The optical path stabilization supplementary module is used to correct the optical path deviation caused by the rotation of the film surface in real time.

[0014] Furthermore, the helical motion component includes a moving component and a rotating component arranged inside the test bench, the moving component includes a stepper motor arranged inside the test bench, a ball screw arranged on one side of the stepper motor output shaft, the ball screw arranged inside the test bench, a connecting disk arranged at the top of the nut inside the ball screw, a moving column arranged at the top of the connecting disk, a moving hole opened in the middle of the test bench, and the top of the moving column slides within the moving hole.

[0015] Furthermore, the rotating assembly includes a rack arranged inside the test bench, a rotating tooth arranged in the connecting disk, the rotating tooth is meshed with the rack, a support block is arranged at the bottom of the rotating tooth, the top of the rotating tooth is connected to a rotating column through an anti-interference component, the rotating column rotates inside the moving column, and the top of the rotating column is connected to the sample table through the moving hole.

[0016] Furthermore, the support block is in an inverted "T" shape, and the support block is limited to rotate inside the nut of the ball screw.

[0017] Furthermore, the rack is thicker than the rotating tooth in the vertical direction, and the rotating tooth is engaged with the middle part of the rack.

[0018] Furthermore, the anti-interference component includes a buffer assembly arranged inside the rotating column, the buffer assembly includes a sliding column arranged at the top of the rotating tooth, sliding blocks symmetrically arranged on both sides of the sliding column, and the sliding column is limited and slides in the rotating column as a whole by the sliding blocks on both sides, and a buffer groove is opened in the rotating column to match the sliding column and the sliding block.

[0019] Furthermore, the anti-interference component also includes a limiting assembly arranged on the side wall of the rotating column, and the limiting assembly includes an abutment groove opened on the wall of the movable hole, a limiting plate arranged in the abutment groove, and a limiting groove opened on the side wall of the rotating column, and the middle part of the limiting plate is rotatably connected to the limiting groove.

[0020] Furthermore, in the initial state, the laser emission point at the bottom of the integrated probe is located at the center of the sample stage.

[0021] Compared with the prior art, the present invention has the following beneficial effects:

[0022] 1. The helical motion component creates an Archimedean spiral trajectory on the optical diaphragm, ensuring equidistant radial coverage. This evenly distributes measurement points within a two-dimensional plane, covering the entire area from center to edge, enabling full-area scanning. This shortens measurement time and reduces the impact of environmental variables (such as temperature and humidity). Compared to single-point static measurement, this system offers rapid traversal and real-time feedback. Combined with the closed-loop control of the motion platform, it can dynamically adjust measurement parameters (such as laser power and integration time) during the scanning process.

[0023] 2. When the sample stage moves, the path of the measurement points obtained by the laser emission point located in the middle of the bottom of the integrated probe on the optical diaphragm is in the shape of an Archimedean spiral, which can be used to analyze the spatial distribution characteristics of the diaphragm thickness (such as radial gradient and circumferential uniformity).

[0024] 3. The stepper motor rotates at a constant angular velocity and feeds radially at a uniform speed, forming a continuous spiral trajectory without the need for frequent starting and stopping, thereby avoiding mechanical wear, reducing the number of positioning times, and extending the life of transmission components such as the lead screw and motor.

[0025] 4. The limiting plates are matched with the limiting grooves and the abutment grooves for limiting and abutting, respectively, and are used to limit the rotating column in the horizontal and vertical directions, ensuring the stability of the sample stage during the movement of the rotating column, and having an anti-interference function. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 It is a schematic diagram of the overall three-dimensional structure of the present invention;

[0027] Figure 2 Schematic diagram of the overall internal structure of the sample stage of the present invention;

[0028] Figure 3 is a schematic diagram of the overall three-dimensional structure of the drive unit of the present invention;

[0029] Figure 4 It is a schematic diagram of a partial three-dimensional structure of the helical motion component of the present invention;

[0030] Figure 5 is a schematic diagram of the overall cross-sectional structure of the drive unit of the present invention;

[0031] Figure 6 Schematic diagram of the exploded structure of the helical motion component of the present invention;

[0032] Figure 7 Schematic diagram of the exploded structure of the buffer assembly of the present invention;

[0033] Figure 8 For the present invention Figure 5 Schematic diagram of the enlarged structure at A in the middle;

[0034] Figure 9 Schematic diagram of the spiral measurement path of the integrated probe of the present invention on the optical membrane of the sample stage.

[0035] In the picture:

[0036] 1. Test box; 11. Test bench; 12. Connecting wire; 13. Integrated probe; 14. Sample stage; 2. Moving assembly; 21. Stepper motor; 22. Ball screw; 23. Connecting plate; 24. Moving column; 25. Moving hole; 3. Rotating assembly; 31. Rack; 32. Rotating gear; 33. Support block; 34. Rotating column; 4. Buffer assembly; 41. Sliding column; 42. Sliding block; 43. Buffer groove; 5. Limit assembly; 51. Abutment groove; 52. Limit plate; 53. Limit groove. DETAILED DESCRIPTION

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

[0038] Example 1, reference Figures 1-9, which is the first embodiment of the present invention, provides an optical film thickness measurement device with anti-interference function, including a test box 1 and a test table 11, a connecting line 12 installed on one side of the test box 1, an integrated probe 13 installed on one side of the test table 11, the integrated probe 13 and the test box 1 are connected by the connecting line 12, and also includes a sample table 14 installed on the test table 11 (the above are all existing technologies and are not described in detail), a driving unit installed inside the test table 11, a rotation synchronization device installed on the sample table 14, and an optical path stabilization compensation module; the driving unit includes a helical motion component and an anti-interference component; the helical motion component is used to drive the sample table 1 4. It moves horizontally while rotating. An anti-interference component is used to reduce the potential for slight mechanical vibrations generated by the spiral motion component driving the sample stage 14, which could cause vibrations on the optical film on the sample stage 14 and affect the measurement results. A rotation synchronization device can be installed on the sample stage 14 to synchronize the sample stage 14's rotation angle signal with the interferometer sampling trigger (e.g., capturing one frame every 0.1° of rotation), enabling point-by-point scanning of the rotating sample (this is prior art). An optical path stabilization compensation module can incorporate a fast reflector (such as a MEMS galvanometer) to correct for optical path deviations caused by film surface rotation in real time (this is prior art), maintaining θ (the laser incident angle) ≈ 0°. To achieve more accurate measurement results, the software algorithm can be optimized and motion trajectory modeling can be performed. Assuming the spiral trajectory is r = a + bθ (a is the initial radius, b is the pitch), coordinate transformation is used to convert the polar coordinate data into a rectangular coordinate system, reconstruct the film thickness distribution, and optimize the measurement results.

[0039] Specifically, during testing, the optical film to be tested is placed on sample stage 14 and aligned to its center. The test chamber 1 and the spiral motion component are activated, causing the sample stage 14 to rotate and move simultaneously. Since the laser emitted from the bottom of the integrated probe 13 is fixed, the movement of the sample stage 14 causes the laser emission point at the bottom of the integrated probe 13 to trace an Archimedean spiral on the optical film. The spiral equation is r = a + bθ, and the radius r increases uniformly with the angle θ. This allows for equidistant radial coverage, evenly distributing measurement points within a two-dimensional plane, covering the entire area from center to edge, completing a full-area scan. This shortens overall measurement time and reduces the influence of environmental variables (such as temperature and humidity). Compared to single-point static measurement, this system offers rapid traversal and real-time feedback. It can be combined with closed-loop control of the motion platform to dynamically adjust measurement parameters (such as laser power and integration time) during the scanning process.

[0040] Reference Figure 1-Figure 3The spiral motion component includes a moving component 2 and a rotating component 3 installed inside the test bench 11. The moving component 2 includes a stepper motor 21 fixedly connected to the test bench 11, a ball screw 22 fixedly connected to one side of the output shaft of the stepper motor 21, the ball screw 22 is limited to rotate inside the test bench 11, a connecting disk 23 fixedly connected to the top of the nut inside the ball screw 22, a moving column 24 fixedly connected to the top of the connecting disk 23, a moving hole 25 is opened in the middle of the test bench 11, and the top of the moving column 24 is limited to slide in the moving hole 25.

[0041] Specifically, when the stepper motor 21 is started, it drives the ball screw 22 to rotate, and the ball screw 22 drives the connecting disk 23 on its top to move synchronously, thereby making the moving column 24 move in the moving hole 25, driving the sample stage 14 to move linearly along the moving hole 25. The stepper motor 21 can achieve high-precision, extremely low-speed drive without cumulative error, and the ball screw 22 can achieve high-precision, low-speed positioning. In combination with the stepper motor 21, the sample stage 14 can achieve low-speed and stable movement to ensure the accuracy of the measurement results. The stepper motor 21 rotates at a constant angular velocity and feeds radially at a uniform speed to form a continuous spiral trajectory without frequent starting and stopping, thereby avoiding reducing mechanical wear, reducing the number of positioning times, and extending the life of transmission components such as the screw and motor.

[0042] Reference Figure 1-Figure 5 The rotating assembly 3 includes a rack 31 fixedly connected to the inside of the test table 11, a rotating tooth 32 rotatably connected to the connecting plate 23, the rotating tooth 32 is meshed with the rack 31, and a support block 33 fixedly connected to the bottom of the rotating tooth 32. The top of the rotating tooth 32 is connected to a rotating column 34 through an anti-interference component. The rotating column 34 rotates inside the moving column 24, and the top of the rotating column 34 passes through the moving hole 25 and is connected to the sample table 14.

[0043] Specifically, when the movable column 24 and the connecting plate 23 move synchronously, the internal rotating teeth 32 move synchronously under the limited support of the support block 33. As the rotating teeth 32 engage with the rack 31, the rotating teeth 32 rotate. The rotating teeth 32 then drive the rotating column 34 to rotate synchronously through the anti-interference component, causing the sample stage 14 on top of it to rotate. The number of teeth on the rotating teeth 32 and the rack 31 can be adjusted to allow the rotating teeth 32 to rotate at a lower speed, facilitating multi-point testing of optical films.

[0044] Reference Figure 7 The support block 33 is in an inverted “T” shape, and the support block 33 is limited to rotate inside the nut of the ball screw 22.

[0045] Specifically, it can be used to provide support force and provide the rotating tooth 32 with a rotation space inside the connecting disk 23, thereby preventing the rotating tooth 32 from generating friction with the inside of the connecting disk 23 and affecting the rotation of the rotating tooth 32 and the smooth transmission of its power.

[0046] Reference Figure 3 and Figure 5 The rack 31 is thicker than the rotating tooth 32 in the vertical direction, and the rotating tooth 32 is engaged with the middle part of the rack 31.

[0047] Specifically, when the motor runs and drives the ball screw 22 to rotate, mechanical vibration is inevitable. The vibration will have a great impact on the rotation of the sample stage 14, thereby causing errors in the measurement results. When it vibrates slightly, the rotating tooth 32 can move slightly upward along the rack 31 and will not disengage from the rack 31, thereby improving the stability of power transmission.

[0048] Example 2, reference Figure 6-Figure 7 , which is the second embodiment of the present invention. This embodiment is different from the first embodiment in that: the anti-interference component includes a buffer assembly 4 installed inside the rotating column 34, the buffer assembly 4 includes a sliding column 41 fixedly connected to the top of the rotating tooth 32, and sliding blocks 42 symmetrically fixedly connected to both sides of the sliding column 41, and the sliding column 41 is integrally limited and slidable in the rotating column 34 by the sliding blocks 42 on both sides, and a buffer groove 43 is provided in the rotating column 34 to match the sliding column 41 and the sliding block 42.

[0049] Specifically, when the helical motion component moves and produces up and down vibrations, the connecting disk 23 drives the rotating teeth 32 to vibrate, and the rotating teeth 32 drives the sliding column 41 to vibrate. The sliding column 41 moves up and down in the buffer groove 43. There is a buffer space in the buffer groove 43, which can avoid the sliding column 41 and the rotating column 34 being rigidly connected and synchronously vibrating up and down, causing the sample table 14 on the top of the rotating column 34 to vibrate, thereby affecting the measurement. The sliding blocks 42 on both sides are used to drive the rotating column 34 to rotate synchronously.

[0050] Reference Figure 8 The anti-interference component also includes a limit assembly 5 installed on the side wall of the rotating column 34. The limit assembly 5 includes an abutment groove 51 opened on the wall of the moving hole 25, a limit plate 52 slidingly connected in the abutment groove 51, and a limit groove 53 opened on the side wall of the rotating column 34, and the middle part of the limit plate 52 is rotatably connected to the limit groove 53.

[0051] Specifically, the limiting plate 52 is matched with the limiting groove 53 and the abutment groove 51 for limiting and abutting, respectively, and is used to limit the rotating column 34 in the horizontal and vertical directions, ensuring the stability of the rotating column 34 in the process of driving the sample stage 14 to move, and has an anti-interference function. In order to improve the stability of the movement of the rotating column 34, steel balls for reducing the moving friction can be arranged between the limiting plate 52 and the limiting groove 53 and the abutment groove 51.

[0052] Reference Figure 1 and Figure 9In the initial state, the laser emission point at the bottom of the integrated probe 13 is at the center of the sample stage 14.

[0053] Specifically, when the sample stage 14 moves, the path of the measurement points obtained by the laser emission point located at the center of the bottom of the integrated probe 13 on the optical membrane is an Archimedean spiral, which can be used to analyze the spatial distribution characteristics of the membrane thickness (such as radial gradient and circumferential uniformity). The remaining structure is the same as that of Example 1.

[0054] In summary, the working principle of the present invention is as follows: during testing, the optical film to be tested is placed on sample stage 14 and aligned to the center of sample stage 14. The test chamber 1 and the spiral motion component are activated, causing sample stage 14 to rotate and move simultaneously. Since the laser emitted from the bottom of the integrated probe 13 is fixed, the sample stage 14 moves at this time, causing the laser emission point at the bottom of the integrated probe 13 to trace an Archimedean spiral on the optical film. The spiral equation is r = a + bθ, and the radius r increases uniformly with angle θ. This allows for equidistant radial coverage, evenly distributing measurement points within a two-dimensional plane, covering the entire area from center to edge, completing a full-area scan, shortening overall measurement time, and reducing the influence of environmental variables (such as temperature and humidity). Compared to single-point static measurement, this method offers rapid traversal and real-time feedback. It can be combined with closed-loop control of the motion platform to dynamically adjust measurement parameters (such as laser power and integration time) during the scanning process.

[0055] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solutions of the present invention may be modified or replaced by equivalents without departing from the spirit and scope of the technical solutions of the present invention, which should all be included in the scope of the claims of the present invention.

Claims

1. An optical film thickness measuring device with an anti-interference function, comprising a test box (1) and a test table (11), a connecting line (12) arranged on one side of the test box (1), an integrated probe (13) arranged on one side of the test table (11), the integrated probe (13) and the test box (1) being connected via the connecting line (12), characterized in that: It also includes a sample stage (14) arranged on the test stage (11), a driving unit arranged inside the test stage (11), a rotation synchronization device arranged on the sample stage (14), and an optical path stabilization compensation module; The driving unit includes a helical motion component and an anti-interference component; The helical motion component is used to drive the sample stage (14) to move in the horizontal direction while rotating; The anti-interference component is used to reduce the vibration of the optical film on the sample stage (14) caused by the slight mechanical vibration generated when the spiral motion component drives the sample stage (14) to move, thereby affecting the measurement result; The rotation synchronization device is used to synchronize the rotation angle signal of the sample stage (14) with the sampling trigger of the interferometer; The optical path stabilization compensation module is used to correct the optical path deviation caused by the rotation of the film surface in real time; The helical motion component includes a moving assembly (2) and a rotating assembly (3) arranged inside the test bench (11), the moving assembly (2) includes a stepping motor (21) arranged inside the test bench (11), a ball screw (22) arranged on one side of the output shaft of the stepping motor (21), the ball screw (22) arranged inside the test bench (11), a connecting disk (23) arranged on the top of the nut inside the ball screw (22), a moving column (24) arranged on the top of the connecting disk (23), a moving hole (25) opened in the middle of the test bench (11), and the top of the moving column (24) limitedly slides in the moving hole (25); The rotating assembly (3) includes a rack (31) arranged inside the test table (11), a rotating tooth (32) arranged in the connecting plate (23), the rotating tooth (32) meshingly connected with the rack (31), a support block (33) arranged at the bottom of the rotating tooth (32), the top of the rotating tooth (32) is connected to a rotating column (34) through an anti-interference component, the rotating column (34) rotates inside the moving column (24), and the top of the rotating column (34) passes through the moving hole (25) and is connected to the sample table (14); The anti-interference component includes a buffer assembly (4) arranged inside the rotating column (34), the buffer assembly (4) includes a sliding column (41) arranged on the top of the rotating tooth (32), and sliding blocks (42) symmetrically arranged on both sides of the sliding column (41), and the sliding column (41) is integrally limited and slidable in the rotating column (34) by the sliding blocks (42) on both sides, and a buffer groove (43) is provided in the rotating column (34) and matches the sliding column (41) and the sliding block (42).

2. The optical film thickness measuring device with anti-interference function according to claim 1, characterized in that: The support block (33) is in an inverted "T" shape, and the support block (33) is limited in rotation inside the nut of the ball screw (22).

3. The optical film thickness measuring device with anti-interference function according to claim 1, characterized in that: The rack (31) is thicker than the rotating tooth (32) in the vertical direction, and the rotating tooth (32) is engaged with the middle portion of the rack (31).

4. The optical film thickness measuring device with anti-interference function according to claim 1, characterized in that: The anti-interference component further includes a limiting assembly (5) arranged on the side wall of the rotating column (34), the limiting assembly (5) including an abutting groove (51) provided on the hole wall of the movable hole (25), a limiting plate (52) provided in the abutting groove (51), and a limiting groove (53) provided on the side wall of the rotating column (34), wherein the middle portion of the limiting plate (52) is rotatably connected to the limiting groove (53).

5. The optical film thickness measuring device with anti-interference function according to claim 1, characterized in that: In the initial state, the laser emission point at the bottom of the integrated probe (13) is located at the center of the sample stage (14).

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