An on-line testing device for the film thickness evolution and distribution of a spin-coated film

Abstract

The present invention discloses an on-line testing device for the film thickness evolution and distribution of a spin-coated film, which comprises a spin-coating film forming unit and a testing and positioning unit. Based on the principle of monochromatic light interference, the present invention conducts on-line testing on the spin-coating process of a specified local area. The film thickness evolution process of the said area is calculated through the evolution of the measured interference images. The present invention provides an efficient testing device for exploring the film thickness evolution mechanism of different position areas of the film in the spin-coating film forming technology and further the full-plane film thickness evolution. The present invention fully takes into account the characteristics of the spin-coating film forming technology, such as short time, high rotation speed and high stability requirements. By indirectly connecting the synchronous cover with the spin-coating turntable, that is, the testing and positioning unit is connected with the spin-coating turntable through a transmission gear set, and the optical detection unit rotates synchronously with the film to be measured. Under the premise of ensuring the high-speed and stable operation of the spin-coating turntable, continuous testing is carried out on the evolution of the interference images of a local area on the substrate.

Description

Technical Field

[0001] The present invention belongs to the technical field of on-line testing of spin-coated films, and particularly relates to an on-line testing device for the film thickness evolution and distribution of spin-coated films. Background Art

[0002] Spin coating technology is a thin film preparation technology with simple principle, good controllability and high repeatability. The film thickness and thickness uniformity of thin film devices determine the device performance, accuracy and efficiency, and are important evaluation indicators of spin coating technology. Mastering the film thickness evolution and distribution during the coating process through on-line testing is of great significance for the theoretical research of spin coating technology. The interference method is a simple and easy-to-implement method in the current thin film testing field. The laws of spin-coated film thickness evolution are different in different regions, resulting in different final film thickness distribution characteristics. Due to the characteristics of short spin coating process time, high rotation speed and high requirement for high stability, the current optical interference method is only applicable to single point testing at the rotation center or film thickness testing on the circumferential direction of a fixed radius. The film thickness information obtained in a single test is limited, and only reflects the film thickness change at a certain point or a certain radius position. When performing local area or global film thickness evolution testing, it is necessary to repeat the test multiple times and integrate the data, especially in the testing of large-area substrates, the efficiency is low. Therefore, there is an urgent need for a device that can realize real-time testing of local area or global film thickness evolution and distribution during the spin coating process. Summary of the Invention

[0003] To solve the above problems existing in the prior art, the present invention provides an on-line testing device for the film thickness evolution and distribution of spin-coated films, which can not only accurately locate any position in the film-covered area of the substrate, but also perform on-line testing of the film thickness evolution in a certain area on the substrate on the premise of ensuring the high-speed and stable operation of the spin coating turntable, and further reflect the film distribution during the spin coating process.

[0004] To achieve the above functions, the technical solution of the present invention is as follows:

[0005] An on-line testing device for the film thickness evolution and distribution of spin-coated films, comprising a spin coating film forming unit and a testing and positioning unit.

[0006] The spin coating film forming unit includes a spin coating turntable and a substrate. The substrate is fixed at the rotation center of the spin coating turntable, and a thin film is spin-coated on the surface of the substrate. The area where the thin film is spin-coated on the surface of the substrate is the film-covered area; the spin coating unit is used to set different angular velocities ω to provide film thickness evolution samples at different rotation speeds.

[0007] The testing and positioning unit includes an optical testing module and a positioning module;

[0008] The optical test module includes a CCD camera, a microscopic lens, a monochromatic light coaxial light source, and a focusing support. The CCD camera is a high-frame-rate camera with wireless transmission or built-in storage function and is connected to the eyepiece end of the microscopic lens; the monochromatic light coaxial light source is connected to the objective end of the microscopic lens; the microscopic lens is connected to the focusing support. The optical test module uses the principle of monochromatic light interference to continuously record the evolution of the interference images in a specified local area.

[0009] The positioning module includes a synchronous cover, an electric lead screw guide rail set, a counterweight, a transmission gear set, and an annular slide rail; the synchronous cover includes a panel and a cylinder, the panel is fixedly connected to the upper end of the cylinder, a transparent thin plate is arranged on the panel, and the area of the transparent thin plate is larger than the area of the substrate and completely covers the substrate; mounting holes are uniformly arranged along the circumferential edge of the panel; the lower end of the synchronous cover is slidably connected to the annular slide rail;

[0010] The electric lead screw guide rail set includes two lead screw guide rails, a gear set composed of three bevel gears, and a driving motor; the two lead screw guide rails are horizontally symmetrically placed coaxially, the inner ends of the lead screws of the two lead screw guide rails are respectively connected to two bevel gears; the output shaft of the driving motor is connected to the central bevel gear; the driving motor drives the bevel gears on both sides to rotate simultaneously through the central bevel gear, thereby driving the lead screws on both sides to rotate, and driving the sliders on the lead screw guide rails on both sides to move outward or inward simultaneously; the outer ends of the lead screw guide rails are fixedly connected to the mounting holes on the panel through bolts.

[0011] The optical test module is installed on the slider on one side of the lead screw guide rail set, and the counterweight is installed on the slider on the other side of the moving lead screw guide rail set to ensure the mass balance of the positioning module.

[0012] The positioning module realizes the radial movement of the optical test module through the lead screw guide rail set, and the moving distance is greater than the maximum distance from the center of the substrate to the edge.

[0013] The spin coating film forming unit and the test and positioning unit are connected through a transmission gear set and rotate synchronously. The transmission gear set includes a driving wheel installed on the main shaft of the spin coating turntable, an internal gear ring installed inside the synchronous cover, and several even-numbered intermediate gears, and the gear ratio distribution ensures that the rotation speeds of the spin coating turntable and the synchronous cover are the same.

[0014] Further, the substrate is a polygon with the number of sides n greater than or equal to 3 or a circle.

[0015] Further, 36 mounting holes are uniformly distributed along the circumferential edge of the panel.

[0016] Further, the working method of the on-line testing device for the evolution and distribution of the spin coating film thickness includes the following steps:

[0017] A. Select a suitable mounting hole on the panel to install and fix the lead screw guide rail set according to the target observation area, where the target observation area can be at any position on the coated substrate;

[0018] B. The lead screw guide rail set drives the optical test module to move, so that the field of view of the CCD camera moves from the initial area at the center of the substrate to the edge of the substrate. The edge area is the zero-order fringe calibration area. Record the edge coordinate position, and calibrate the coordinate position from the center to the edge as the effective test area;

[0019] C. Set the rotation speed of the spin coater turntable. During the spin coating process, the optical test module moves to the target observation area and turns on the monochromatic light coaxial light source. The monochromatic light coaxial light source generates monochromatic light, which is reflected by the built-in semi-transparent and semi-reflective mirror and vertically irradiates the film on the substrate. After the light path passes through the upper surface of the film, the upper surface reflected light is generated by reflection. After the light path passes through the lower surface of the film, the lower surface reflected light is generated by reflection. The upper surface reflected light and the lower surface reflected light form interference light, and the interference light is transmitted through the semi-transparent and semi-reflective mirror to reach the CCD camera; the CCD camera starts to intercept the interference image and record its coordinate position; when the spin coater turntable rotates, the driving wheel fixed on the spin coater turntable rotates synchronously, and the torque is transmitted through the intermediate gear, driving the internal gear ring and the synchronous cover to rotate synchronously with the spin coater turntable;

[0020] D. After the spin coater turntable stops, move the optical test module to the edge of the substrate, and continuously record the interference images on the path until the zero-order fringe image at the edge is detected, and then turn off the CCD camera.

[0021] Further, in step B, if the target observation area itself is located at the edge of the substrate, the zero-order fringe calibration in step D is omitted.

[0022] Compared with the existing film thickness testing device, the beneficial effects of the present invention are:

[0023] 1. Based on the principle of monochromatic light interference, the present invention conducts on-line testing on the spin coating process of a specified local area. The film thickness evolution process of the area is calculated through the evolution of the measured interference images. It provides an efficient testing device for exploring the film thickness evolution mechanism of different position areas of the film in the spin coating film formation technology and further the full-plane film thickness evolution.

[0024] 2. The present invention fully considers the characteristics of the spin coating film formation technology, such as short time, high rotation speed and high stability requirements. By indirectly connecting the synchronous cover with the spin coater turntable, that is, the testing and positioning unit is connected with the spin coater turntable through the transmission gear set, and the optical detection unit rotates synchronously with the measured film. On the premise of ensuring the high-speed and stable operation of the spin coater turntable, continuous testing is carried out on the evolution of the interference images of a certain local area on the substrate.

[0025] 3. The present invention controls the coaxial opposed lead screw guide driven by a single motor, so that the synchronous cover also maintains real-time mass balance during the movement of the optical test module; during the movement of the optical test module, the polar coordinate position of the observation area on the substrate can be accurately recorded, and the corresponding relationship between the film thickness evolution process and the coordinate position is established. It avoids the coordinate offset caused by the relative movement between the object under test and the test device. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 It is a schematic structural diagram of the present invention.

[0027] Figure 2 It is a schematic structural diagram of the electric lead screw guide group.

[0028] Figure 3 It is a schematic structural diagram of the transmission gear group.

[0029] Figure 4 It is a schematic optical path diagram of the optical test module.

[0030] Figure 5 It is a schematic diagram for calibrating the effective test area (rectangle).

[0031] In the figure: 1. Spin coating turntable, 2. Substrate, 3. Synchronous cover, 4. Electric lead screw guide group, 5. CCD camera, 6. Microscopic lens, 7. Monochromatic light coaxial light source, 8. Focus adjustment frame support, 9. Counterweight, 10. Annular slide rail, 11. Transmission gear group, 12. Transparent thin plate, 13. Driving wheel, 14. Intermediate gear, 15. Internal gear ring, 21. Initial area, 22. Target observation area, 23. Zero-order fringe calibration area, 24. Effective test area, 31. Upper surface reflected light, 32. Lower surface reflected light, 33. Thin film, 34. Half-transmissive and half-reflective mirror. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0032] The present invention will be further described below with reference to the accompanying drawings. As Figures 1-5 shown, an on-line test device for the evolution and distribution of the film thickness of a spin-coated thin film includes a spin coating film forming unit and a test and positioning unit.

[0033] The spin coating film forming unit includes a spin coating turntable 1 and a substrate 2. The substrate 2 is fixed at the rotation center of the spin coating turntable 1, and a thin film 33 is spin-coated on the surface of the substrate 2. The area where the thin film is spin-coated on the surface of the substrate 2 is the film coating area; the spin coating unit is used to set different angular velocities ω to provide film thickness evolution samples at different rotation speeds.

[0034] The test and positioning unit includes an optical test module and a positioning module;

[0035] The optical test module includes a CCD camera 5, a microscopic lens 6, a monochromatic light coaxial light source 7, and a focusing bracket 8. The CCD camera 5 is a high-frame-rate camera with wireless transmission or built-in storage functions and is connected to the eyepiece end of the microscopic lens 6. The monochromatic light coaxial light source 7 is connected to the objective end of the microscopic lens 6. The microscopic lens 6 is connected to the focusing bracket 8. The optical test module uses the monochromatic light interference principle to continuously record the evolution of the interference images in a specified local area.

[0036] The positioning module includes a synchronous cover 3, an electric lead screw guide rail group 4, a counterweight 9, a transmission gear group 11, and an annular slide rail 10. The synchronous cover 3 includes a panel and a cylinder. The panel is fixedly connected to the upper end of the cylinder. A transparent thin plate 12 is provided on the panel. The area of the transparent thin plate 12 is larger than the area of the substrate 2 and completely covers the substrate 2. Mounting holes are uniformly arranged along the circumferential edge of the panel. The lower end of the synchronous cover 3 is slidably connected to the annular slide rail 10.

[0037] The electric lead screw guide rail group 4 includes two lead screw guide rails, a gear group composed of three bevel gears, and a driving motor. The two lead screw guide rails are horizontally symmetrically placed coaxially. The inner ends of the lead screws of the two lead screw guide rails are respectively connected to two bevel gears. The output shaft of the driving motor is connected to the central bevel gear. The driving motor drives the bevel gears on both sides to rotate simultaneously through the central bevel gear, thereby driving the rotation of the lead screws on both sides, and driving the sliders on the lead screw guide rails on both sides to move outward or inward simultaneously. The outer ends of the lead screw guide rails are fixedly connected to the mounting holes on the panel through bolts.

[0038] The optical test module is installed on the slider on one side of the lead screw guide rail group, and the counterweight 9 is installed on the slider on the other side of the moving lead screw guide rail group to ensure the mass balance of the positioning module.

[0039] The positioning module realizes the radial movement of the optical test module through the lead screw guide rail group, and the moving distance is greater than the maximum distance from the center to the edge of the substrate 2.

[0040] The spin coating film forming unit and the test and positioning unit are connected through the transmission gear group 11 and rotate synchronously. The transmission gear group 11 includes a driving wheel 13 installed on the main shaft of the spin coating turntable 1, an internal gear ring 15 installed inside the synchronous cover 3, and a number of even intermediate gears 14, and the gear ratio distribution ensures that the rotation speeds of the spin coating turntable 1 and the synchronous cover 3 are the same.

[0041] Further, the substrate 2 is a polygon or a circle with the number of sides n greater than or equal to 3.

[0042] Further, 36 mounting holes are uniformly distributed along the circumferential edge of the panel.

[0043] The working method of the on-line testing device for the film thickness evolution and distribution of the spin-coated film 33 includes the following steps:

[0044] A. Select a suitable mounting hole on the panel according to the target observation area 22 and install and fix the lead screw guide rail set, where the target observation area 22 can be at any position on the coated substrate 2;

[0045] B. The lead screw guide rail set drives the optical test module to move, so that the field of view of the CCD camera 5 moves from the initial area 21 at the center of the substrate 2 to the edge of the substrate 2. The edge area is the zero-order fringe calibration area 23. Record the edge coordinate position, and calibrate the coordinate position from the center to the edge as the effective test area 24;

[0046] C. Set the rotation speed of the spin coating turntable 1. During the spin coating process, the optical test module moves to the target observation area 22 and turns on the monochromatic light coaxial light source 7. The monochromatic light coaxial light source 7 generates monochromatic light, which is reflected by the built-in semi-transparent and semi-reflective mirror 34 and vertically irradiates the film 33 on the substrate 2. After the light path passes through the upper surface of the film 33, the upper surface reflected light 31 is generated by reflection. After the light path passes through the lower surface of the film 33, the lower surface reflected light 32 is generated by reflection. The upper surface reflected light 31 and the lower surface reflected light 32 form interference light, and the interference light is transmitted through the semi-transparent and semi-reflective mirror 34 to reach the CCD camera 5; the CCD camera 5 starts to intercept the interference image and record its coordinate position; when the spin coating turntable 1 rotates, the driving wheel 13 fixed on the spin coating turntable 1 rotates synchronously, transmits torque through the intermediate gear 14, and drives the internal gear ring 15 and the synchronous cover 3 to rotate synchronously with the spin coating turntable 1;

[0047] D. After the spin coating turntable 1 stops, move the optical test module to the edge of the substrate 2, continuously record the interference images on the path until the zero-order fringe image at the edge is detected, and then turn off the CCD camera 5.

[0048] Further, in step B, if the target observation area 22 is itself located at the edge of the substrate 2, the zero-order fringe calibration in step D is omitted.

[0049] The present invention is not limited to this embodiment. Any equivalent concept or change within the technical scope disclosed in the present invention shall be included in the protection scope of the present invention.

Claims

1. An on-line testing device for the film thickness evolution and distribution of a spin-coated film, characterized in that: It includes a spin coating film forming unit and a testing and positioning unit; The spin coating film forming unit includes a spin coating turntable (1) and a substrate (2); the substrate (2) is fixed at the rotation center of the spin coating turntable (1), and a thin film (33) is spin coated on the surface of the substrate (2), and the area where the thin film is spin coated on the surface of the substrate (2) is the film covering area; the spin coating film forming unit is used to set different angular velocities ω to provide film thickness evolution samples at different rotation speeds; The testing and positioning unit includes an optical testing module and a positioning module; The optical testing module includes a CCD camera (5), a microscopic lens (6), a monochromatic light coaxial light source (7) and a focusing frame support (8), the CCD camera (5) is a high frame rate camera with wireless transmission or built-in storage function, and is connected to the eyepiece end of the microscopic lens (6); the monochromatic light coaxial light source (7) is connected to the objective end of the microscopic lens (6); the microscopic lens (6) is connected to the focusing frame support (8); the optical testing module uses the principle of monochromatic light interference to continuously record the evolution of the interference image in a specified local area; The positioning module includes a synchronous cover (3), an electric screw rail group (4), a counterweight (9), a transmission gear group (11) and an annular slide rail (10); the synchronous cover (3) includes a panel and a cylinder, the panel is fixedly connected to the upper end of the cylinder, a transparent thin plate (12) is arranged on the panel, and the area of the transparent thin plate (12) is larger than the area of the substrate (2) and completely covers the substrate (2); mounting holes are uniformly arranged along the circumferential edge of the panel; the lower end of the synchronous cover (3) is slidably connected to the annular slide rail (10); The electric screw rail group (4) includes two screw rails, a gear group composed of three bevel gears and a driving motor; the two screw rails are placed horizontally and symmetrically coaxially, and the inner ends of the screws of the two screw rails are respectively connected to two bevel gears; the output shaft of the driving motor is connected to the central bevel gear; the driving motor drives the bevel gears on both sides to rotate simultaneously through the central bevel gear, thereby driving the screws on both sides to rotate, and driving the sliders on the screw rails on both sides to move outward or inward at the same time; the outer ends of the screw rails are fixedly connected to the mounting holes on the panel through bolts; The optical testing module is installed on the slider on one side of the screw rail group, and the counterweight (9) is installed on the slider on the other side of the moving screw rail group to ensure the mass balance of the positioning module; The positioning module realizes the radial movement of the optical testing module through the screw rail group, and the moving distance is greater than the maximum distance from the center of the substrate (2) to the edge; The spin coating film forming unit and the testing and positioning unit are connected through a transmission gear group (11) and keep synchronous rotation; the transmission gear group (11) includes a driving wheel (13) installed on the main shaft of the spin coating turntable (1), an internal gear ring (15) installed inside the synchronous cover (3) and a number of even intermediate gears (14), and the gear ratio distribution ensures that the rotation speeds of the spin coating turntable (1) and the synchronous cover (3) are the same.

2. The on-line testing device for the evolution and distribution of the thickness of a spin-coated thin film according to claim 1, characterized in that: The substrate (2) is a polygon or a circle with the number of sides n greater than or equal to 3.

3. The on-line testing device for the evolution and distribution of the thickness of a spin-coated thin film according to claim 1, characterized in that: 36 mounting holes are uniformly distributed along the circumferential edge of the panel.

4. The on-line testing device for the evolution and distribution of the film thickness of a spin-coated film according to claim 1, wherein: The working method of the on-line testing device for the film thickness evolution and distribution of the spin-coated film (33) includes the following steps: A. Select a suitable mounting hole on the panel according to the target observation area (22) and install and fix the lead screw guide rail group. The target observation area (22) can be at any position on the coated substrate (2). B. The lead screw guide rail group drives the optical test module to move, so that the field of view of the CCD camera (5) moves from the initial area (21) at the center of the substrate (2) to the edge of the substrate (2). The edge area is the zero-order fringe calibration area (23). Record the edge coordinate position, and calibrate the area from the center to the edge coordinate position as the effective test area (24). C. Set the rotation speed of the spin coating turntable (1). During the spin coating process, the optical test module moves to the target observation area (22) and turns on the monochromatic light coaxial light source (7). The monochromatic light coaxial light source (7) generates monochromatic light. After being reflected by the built-in semi-transparent and semi-reflective mirror (34) inside it, it vertically irradiates the film (33) on the substrate (2). The light path reflects after passing through the upper surface of the film (33) to generate the upper surface reflected light (31), and the light path reflects after passing through the lower surface of the film (33) to generate the lower surface reflected light (32). The upper surface reflected light (31) and the lower surface reflected light (32) form interference light. The interference light transmits through the semi-transparent and semi-reflective mirror (34) and reaches the CCD camera (5). The CCD camera (5) starts to intercept the interference image and record its coordinate position. When the spin coating turntable (1) rotates, the driving wheel (13) fixed on the spin coating turntable (1) rotates synchronously, transmits torque through the intermediate gear (14), and drives the internal gear ring (15) and the synchronous cover (3) to rotate synchronously with the spin coating turntable (1). D. After the spin coating turntable (1) stops, move the optical test module to the edge of the substrate (2), continuously record the interference images on the path until the zero-order fringe image at the edge is detected, and then turn off the CCD camera (5).

5. The on-line testing device for the evolution and distribution of the thickness of a spin-coated thin film according to claim 4, characterized in that: In step B, if the target observation area (22) is itself located at the edge of the substrate (2), the zero-order fringe calibration in step D is omitted.

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