Device and method for dynamically measuring thickness of ultrathin liquid film

Abstract

The invention discloses an ultrathin liquid film dynamic thickness measuring device and method, the device comprises a liquid film sample manufacturing module, a light path module, an image acquisition module and a computer, the image acquisition module comprises a three-dimensional moving device and a high-speed camera fixed on the three-dimensional moving device; the equipment generates coaxial light through the light path module to irradiate the surface of the ultrathin liquid film under a rotating system, and an interference fringe pattern is formed by using the interference characteristics of reflected light of the upper and lower interfaces of the ultrathin liquid film. A high-speed camera in the image acquisition module captures an interference image in a liquid film flowing process in real time to realize dynamic-full image liquid film observation; the computer controls the three-dimensional moving device to realize total image-local measurement, and is matched with an image analysis system, so that the liquid film forming and changing process in the integrated circuit manufacturing process can be dynamically tracked in real time, the form and thickness information of the liquid film can be instantaneously acquired, and the real-time and high-precision measurement of the thickness of the ultrathin liquid film is realized.

Description

Technical Field

[0001] The invention belongs to the technical field of detection equipment, and in particular relates to an ultra-thin liquid film dynamic thickness measurement device and method based on the optical interference thickness measurement principle. Background Art

[0002] There are a large number of ultra-thin liquid film flow processes in the integrated circuit manufacturing process, such as photoresist coating, wafer wet cleaning, etching, drying, etc. The flow and rupture of ultra-thin liquid films have an important impact on the process results. The uniformity and stability of the liquid film are directly related to the performance of chip manufacturing, product yield and device stability. Therefore, real-time and dynamic measurement of ultra-thin liquid film thickness is of great significance to ensure the uniformity and stability of the liquid film, and then improve the success rate and product yield of subsequent chip manufacturing processes.

[0003] However, traditional film thickness measurement technology is mainly used for thickness measurement of solid films and analysis of liquid films after solidification, and there is still a lack of dynamic process thickness measurement technology for wet films. In the current integrated circuit manufacturing field, most of the existing instruments and technologies can only meet the single-point measurement needs of static liquid films, and cannot reflect the dynamic changes of film thickness in real time, nor can they provide real-time feedback during the process. Summary of the invention

[0004] The purpose of the present invention is to provide an ultra-thin liquid film dynamic thickness measurement device and method to address the above-mentioned problems in the prior art. The device utilizes the principle of optical interference, combines high-frequency camera technology and three-dimensional mobile fixed-point shooting, and synchronizes algorithm analysis technology to track the formation and change process of the liquid film in the integrated circuit manufacturing process in real time and dynamically, and instantaneously obtain the morphology and thickness information of the liquid film, thereby realizing real-time and high-precision measurement of the thickness of the ultra-thin liquid film.

[0005] To achieve the above purpose, the technical solution adopted by the present invention is as follows:

[0006] The first aspect of the present invention is to provide an ultra-thin liquid film dynamic thickness measurement device, including a liquid film sample preparation module, an optical path module, an image acquisition module and a computer, wherein:

[0007] The liquid film sample preparation module includes a spin coater, a negative pressure chamber arranged on the upper part of the spin coater, a carrier plate arranged in the negative pressure chamber, and a vacuum pump connected to the negative pressure chamber; the carrier plate is used to place the sample; the vacuum pump acts on the negative pressure chamber to apply negative pressure to it to achieve adsorption of the carrier plate.

[0008] The optical path module includes an LED light source, an optical fiber, a coaxial optical lens, and a light source connector arranged on one side of the coaxial optical lens, and a semi-reflective and semi-mirror arranged on the same axis as the coaxial optical lens, and the light source connector is connected to the LED light source through the optical fiber;

[0009] The image acquisition module includes a three-dimensional mobile device and a high-speed camera fixed on the three-dimensional mobile device; the front end of the high-speed camera is connected to the coaxial optical lens and is located directly above the object tray, and is used to obtain image data in real time and transmit it to the computer;

[0010] The computer is used to control the operation of the three-dimensional mobile device. The computer is also equipped with an image analysis system for analyzing and processing image data from a high-speed camera to obtain full-image thickness distribution data of the ultra-thin liquid film sample.

[0011] In this embodiment, the displacement range of the three-dimensional moving device is ±15 mm along the xyz axis.

[0012] In one embodiment of the present invention, the three-dimensional moving device is composed of three micrometer slides that are perpendicular to each other to achieve independent movement on the xyz axis.

[0013] A second aspect of the present invention is to provide a method for dynamic thickness measurement of ultra-thin liquid films based on the ultra-thin liquid film dynamic thickness measurement device, comprising the following steps:

[0014] S1: Place the sample on a carrier plate in a negative pressure chamber, turn on the spin coater and vacuum pump, and spin coat the carrier plate to start preparing the ultra-thin liquid film sample;

[0015] S2: The LED light emitted by the LED light source is transmitted to the semi-reflective and semi-mirror lens, and under its action, coaxial light integrated with the coaxial light lens is generated. The coaxial light irradiates the surface of the ultra-thin liquid film on the carrier plate to generate image data, that is, the interference fringe pattern;

[0016] S3: The high-speed camera captures the interference fringe pattern starting from the center of the carrier plate, and the three-dimensional moving device runs under the control of the computer, driving the high-speed camera to perform dynamic scanning along the radius trajectory of the carrier plate;

[0017] S4: The computer processes and analyzes the interference fringe pattern captured by the high-speed camera through the matching image analysis system to obtain the thickness information of the ultra-thin liquid film and realize real-time feedback of the dynamic changes of the film during the entire spin coating process.

[0018] In this embodiment, the method also includes a full-image measurement step: a high-speed camera is moved by a three-dimensional moving device to realize real-time dynamic monitoring of the entire viewing angle range of the ultra-thin liquid film and the entire process of ultra-thin liquid film flow rupture. After being processed by a computer-supported image analysis system, full-image data is obtained to obtain the overall thickness change of the ultra-thin liquid film.

[0019] In this embodiment, the method also includes a local measurement step. For the full-image data obtained in the full-image measurement step, by adjusting the coaxial light intensity and the magnification of the high-speed camera, a fixed-point analysis is performed on the area with obvious interference fringes to achieve accurate measurement of local changes in the liquid film.

[0020] In this embodiment, the coaxial light intensity is adjusted by adjusting the light source intensity of the LED light source.

[0021] The beneficial effects of the present invention are as follows:

[0022] 1. The present invention utilizes high-frequency camera technology to capture the dynamic changes of ultra-thin liquid films at high speed through a high-speed camera, and cooperates with the computer's image analysis system to achieve real-time measurement of liquid film thickness with nanometer-level accuracy and kilohertz-level sampling frequency, and dynamically and real-time track the formation and change process of ultra-thin liquid films under a rotating system, thus promoting liquid film flow analysis from single-point, static measurement to full-image, dynamic measurement.

[0023] 2. The present invention utilizes a three-dimensional mobile device to realize an organic combination of global and local measurements. By moving the high-speed camera through the three-dimensional mobile device, real-time dynamic monitoring of the entire viewing angle range of the ultra-thin liquid film and the entire process of flow and rupture of the ultra-thin liquid film can be realized. After analysis and processing by the image analysis system matched with the computer, the full-image data is obtained, and the overall thickness change of the ultra-thin liquid film is obtained; for the obtained full-image data, by adjusting the coaxial light intensity and the magnification of the high-speed camera, the area with obvious interference fringes is analyzed at a fixed point, so as to realize the accurate measurement of the local changes of the ultra-thin liquid film.

[0024] 3. The present invention helps to improve the uniformity and stability of the liquid film through dynamic and high-precision measurement of the flow and rupture of the ultra-thin liquid film, thereby improving the performance of chip manufacturing, product yield and device stability, which is of great significance to the development of integrated circuit manufacturing equipment and process optimization. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 It is a schematic diagram of the overall structure of the ultra-thin liquid film dynamic thickness measuring device of the present invention.

[0026] Figure 2 It is a specific structural schematic diagram of the ultra-thin liquid film dynamic thickness measuring device of the present invention.

[0027] Figure 3 It is a partial cross-sectional view of the coaxial optical lens.

[0028] Figure 4 It is a schematic diagram of the optical path design of the ultra-thin liquid film dynamic thickness measuring device of the present invention.

[0029] in:

[0030] 10-liquid film sample preparation module; 11-spin coater; 12-negative pressure chamber; 13-carrying plate; 14-vacuum pump;

[0031] 20-optical path module; 21-LED light source; 22-optical fiber; 23-coaxial optical lens; 24-light source connector; 25-semi-reflective and semi-mirror lens;

[0032] 30-image acquisition module; 31-three-dimensional moving device; 32-high-speed camera;

[0033] 40-Computer. DETAILED DESCRIPTION

[0034] The following is a clear and detailed description of the technical solution of the present invention through specific embodiments in conjunction with the accompanying drawings. It should be understood that the following embodiments are only part of the embodiments of the present invention and are not intended to limit the scope of protection of the present invention. Based on the embodiments of the present invention, other embodiments obtained by those skilled in the art without creative work are all within the scope of protection of the present invention.

[0035] like Figure 1 The ultra-thin liquid film dynamic thickness measurement device shown includes a liquid film sample preparation module 10, an optical path module 20, an image acquisition module 30 and a computer 40, wherein:

[0036] Combination Figure 2 As shown, the liquid film sample preparation module 10 includes a spin coater 11, a negative pressure chamber 12 arranged on the upper part of the spin coater 11, a loading plate 13 arranged in the negative pressure chamber 12, and a vacuum pump 14 connected to the negative pressure chamber 12; the loading plate 13 is used to place samples; the vacuum pump 14 acts on the negative pressure chamber 12 to apply negative pressure thereto to achieve adsorption of the loading plate 13.

[0037] The optical path module 20 includes an LED light source 21, an optical fiber 22, a coaxial optical lens 23, a light source connector 24 arranged on one side of the coaxial optical lens 23, and a semi-reflective semi-mirror 25 (such as a semi-reflective semi-mirror 25) arranged on the same axis as the coaxial optical lens 23. Figure 3 As shown), the light source connector 24 is connected to the LED light source machine 21 through the optical fiber 22;

[0038] The image acquisition module 30 includes a three-dimensional mobile device 31 and a high-speed camera 32 fixed on the three-dimensional mobile device 31;

[0039] The front end of the high-speed camera 32 is connected to the coaxial optical lens 23 and is located directly above the loading tray 13, and is used to obtain image data in real time and transmit it to the computer 40;

[0040] The computer 40 is used to control the operation of the three-dimensional moving device 31 to realize the fixed-point movement of the high-speed camera 32; the computer 40 is also equipped with an image analysis system for analyzing and processing the image data from the high-speed camera 32 to obtain the full-image thickness distribution data of the ultra-thin liquid film sample to realize high-precision automatic analysis of the ultra-thin liquid film thickness.

[0041] like Figure 4 As shown, the LED light emitted by the LED light source 21 is transmitted to the semi-reflective half-mirror 25 through the optical fiber 22 and the light source connector 24, and then under the action of the semi-reflective half-mirror 25, coaxial light integrated with the coaxial light lens 23 is generated, and vertically irradiated to the surface of the ultra-thin liquid film sample in the spin coating process on the carrier plate 13; the optical path design is optimized, and the light pollution and light attenuation effect of the incident light are reduced.

[0042] The coaxial light will be reflected at the upper and lower interfaces of the dynamic ultra-thin liquid film sample respectively, obtaining two coherent light waves, generating interference phenomenon, and due to the uneven film thickness distribution of the dynamic ultra-thin liquid film sample, the optical path difference is different, thereby forming an interference fringe pattern of alternating light and dark; the three-dimensional moving device 31 is programmed and controlled by the computer 40 to realize the fixed-point movement of the high-speed camera 32 it carries, and the high-speed camera 32 captures the interference fringe pattern and cooperates with the coaxial light lens 23 to realize high-frequency image acquisition to capture the dynamic process of liquid film flow and rupture, and transmits the image data to the computer 40 for processing and analysis, thereby realizing dynamic measurement of the ultra-thin liquid film.

[0043] In this embodiment, the displacement range of the three-dimensional moving device 31 is ±15 mm along the xyz axis.

[0044] It should be noted that: in actual application, the three-dimensional moving device 31 can adopt conventional structures such as screw nuts, guide rods and locking nuts, sliders and guide rails, and can be combined as needed to specifically achieve translation in three-axis directions.

[0045] In one embodiment of the present invention, the three-dimensional moving device 31 is composed of three micrometer slides that are perpendicular to each other to achieve independent movement on the xyz axis.

[0046] The method for dynamic thickness measurement of ultra-thin liquid film based on the ultra-thin liquid film dynamic thickness measurement device comprises the following steps:

[0047] S1: placing the sample on the carrier plate 13 of the negative pressure chamber 12, turning on the spin coater 11 and the vacuum pump 14, and rotating the carrier plate 13 for spin coating to start preparing the ultra-thin liquid film sample;

[0048] S2: The LED light emitted by the LED light source 21 is transmitted to the semi-reflective semi-mirror 25, and under its action, a coaxial light integrated with the coaxial light lens 23 is generated. The coaxial light irradiates the surface of the ultra-thin liquid film on the carrier plate 13 to generate image data, that is, an interference fringe pattern;

[0049] S3: The high-speed camera 32 captures the interference fringe pattern starting from the center of the carrier plate 13, and the three-dimensional moving device 31 operates under the control of the computer 40, driving the high-speed camera 32 to perform dynamic scanning along the radius track of the carrier plate 13;

[0050] S4: The computer 40 processes and analyzes the interference fringe pattern captured by the high-speed camera 32 through a matching image analysis system to obtain thickness information of the ultra-thin liquid film, thereby achieving real-time feedback of the dynamic changes of the liquid film during the entire spin coating process.

[0051] In this embodiment, the ultra-thin liquid film sample is a photoresist spin-coated film or a chemical solvent film for wet cleaning of wafers.

[0052] In this embodiment, the method also includes a full-image measurement step: the high-speed camera 32 is moved by a three-dimensional moving device 31 to realize real-time dynamic monitoring of the entire viewing angle range of the ultra-thin liquid film and the entire process of ultra-thin liquid film flow rupture. After being processed by the image analysis system of the computer 40, the full-image data is obtained to obtain the overall thickness change of the ultra-thin liquid film.

[0053] In this embodiment, the method also includes a local measurement step. For the full-image data obtained in the full-image measurement step, by adjusting the coaxial light intensity and the magnification of the high-speed camera 32, a fixed-point analysis is performed on the area with obvious interference fringes to achieve accurate measurement of local changes in the liquid film.

[0054] In this embodiment, the coaxial light intensity is adjusted by adjusting the light source intensity of the LED light source unit 21 , and specific adjustment parameters are determined according to actual conditions.

[0055] The above is a detailed description of the technical solution of the present application. Its purpose is to enable technical personnel familiar with the field to understand the content of the present application and implement it. It cannot be used to limit the scope of protection of the present application. All equivalent changes or modifications made according to the spirit of the present application should be included in the scope of protection of the present application.

Claims

1. An ultra-thin liquid film dynamic thickness measurement device, characterized in that: It comprises a liquid film sample preparation module (10), an optical path module (20), an image acquisition module (30) and a computer (40), wherein: The liquid film sample preparation module (10) comprises a spin coater (11), a negative pressure chamber (12) arranged on the upper part of the spin coater (11), a loading plate (13) placed in the negative pressure chamber (12), and a vacuum pump (14) connected to the negative pressure chamber (12); The optical path module (20) comprises an LED light source machine (21), an optical fiber (22), a coaxial optical lens (23), a light source connector (24) arranged on one side of the coaxial optical lens (23), and a semi-reflective semi-mirror (25) arranged on the same axis as the coaxial optical lens (23); the light source connector (24) is connected to the LED light source machine (21) via the optical fiber (22); The image acquisition module (30) comprises a three-dimensional moving device (31) and a high-speed camera (32) fixed on the three-dimensional moving device (31); the front end of the high-speed camera (32) is connected to the coaxial optical lens (23) and is located directly above the object tray (13) for acquiring image data in real time and transmitting it to the computer (40); The computer (40) is used to control the operation of the three-dimensional moving device (31) and is equipped with an image analysis system for analyzing and processing image data from the high-speed camera (32) to obtain full-image thickness distribution data of the ultra-thin liquid film sample.

2. The ultra-thin liquid film dynamic thickness measurement device according to claim 1, characterized in that: The displacement range of the three-dimensional moving device (31) is ±15 mm along the xyz axis.

3. The ultra-thin liquid film dynamic thickness measurement device according to claim 1, characterized in that: The three-dimensional moving device (31) is composed of three micrometer slides arranged perpendicular to each other to achieve independent movement on the xyz axis.

4. A method for dynamic thickness measurement of ultra-thin liquid film, characterized in that: The ultra-thin liquid film dynamic thickness measurement device according to any one of claims 1 to 3 comprises the following steps: S1: placing a sample on a carrier plate (13) in a negative pressure chamber (12), turning on a spin coater (11) and a vacuum pump (14), and rotating the carrier plate (13) for spin coating to start preparing an ultra-thin liquid film sample; S2: The LED light emitted by the LED light source (21) is transmitted to the semi-reflective semi-mirror (25), and under the action of the semi-reflective semi-mirror (25), a coaxial light integrated with the coaxial light lens (23) is generated. The coaxial light irradiates the surface of the ultra-thin liquid film on the carrier plate (13) to generate image data, i.e., an interference fringe pattern; S3: The high-speed camera (32) captures the interference fringe pattern with the center of the sample tray (13) as the starting point, and the three-dimensional moving device (31) operates under the control of the computer (40), driving the high-speed camera (32) to perform dynamic scanning along the radius track of the sample tray (13); S4: The computer (40) processes and analyzes the interference fringe pattern captured by the high-speed camera (32) through a matching image analysis system to obtain thickness information of the ultra-thin liquid film, thereby achieving real-time feedback of the dynamic changes of the ultra-thin liquid film during the entire spin coating process.

5. The method for dynamic thickness measurement of ultra-thin liquid film according to claim 4, characterized in that: The method further comprises a full-image measurement step: a high-speed camera (32) is moved by a three-dimensional moving device (31) to achieve real-time dynamic monitoring of the entire viewing angle range of the ultra-thin liquid film and the entire process of flow and rupture of the ultra-thin liquid film; after being processed by an image analysis system matched with a computer (40), full-image data is obtained to obtain the overall thickness change of the ultra-thin liquid film.

6. The method for dynamic thickness measurement of ultra-thin liquid film according to claim 5, characterized in that: The method further comprises a local measurement step, wherein for the full image data obtained in the full image measurement step, by adjusting the coaxial light intensity and the magnification of the high-speed camera (32), a fixed-point analysis is performed on an area with obvious interference fringes, thereby achieving accurate measurement of local changes in the ultra-thin liquid film.

7. The method for dynamic thickness measurement of ultra-thin liquid film according to claim 6, characterized in that: The coaxial light intensity is adjusted by adjusting the light source intensity of the LED light source machine (21).

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