Particle detector on photomask plate for photoetching machine

Abstract

The utility model relates to a detector for particles on a photomask plate for a photoetching machine, which is used for detecting two side surfaces of the photomask plate and cleaning small particles on the photomask plate. The detector comprises a rack, a conveying assembly arranged on the rack, at least one cleaning assembly arranged on one side of the conveying assembly, and at least two illumination detector assemblies oppositely arranged on the rack. According to the detector, the photomask plate is transported through the transportation assembly, and the photomask plate sequentially passes through the cleaning assembly and the illumination detector assembly. Laser emitted by the laser emitter is focused through the first convex lens and the second convex lens, tiny particles with the size of 10 microns can be irradiated to the minimum extent, light signals are fed back to the light receiver to be converted into different frequency spectrums, the computer is used for analysis and calculation, diffuse reflection frequency spectrums and position information of the particles with different sizes are obtained, and the position information of the particles with different sizes is obtained. And finally, the photomask plate is cleaned through the cleaning assembly according to the particle information obtained by the computer.

Description

Technical Field

[0001] This utility model relates to the field of semiconductor manufacturing technology, and in particular to a particle detector on a photomask for a lithography machine. Background Technology

[0002] The photomask used in lithography machines plays a crucial role in transferring patterns during the lithography process. Its surface cleanliness requirements are extremely high, typically reaching Class 100 or even higher. Therefore, the cleanliness of the photomask surface directly affects the chip manufacturing quality and production efficiency. With the continuous maturation of semiconductor manufacturing technology, some inspection and cleaning instruments have emerged. For example, Chinese patent CN201910790506.X discloses a photomask inspection device and a photomask cleaning method, which includes: a detection cavity for containing and detecting the presence of particulate matter on the photomask surface; and a purging unit disposed at the end of the detection cavity for purging the photomask entering and / or exiting the detection cavity with gas to remove particulate matter from the photomask surface. This device can save cleaning time and improve the cleaning efficiency of the photomask. However, it can only inspect or clean one side of the photomask, and cannot simultaneously inspect both sides. The inspection and cleaning efficiency still needs improvement, and the particle size that the detection cavity in this device can detect is only 50µm, indicating a limited detection range. Utility Model Content

[0003] In view of this, the present invention provides a particle detector on a photomask for a lithography machine to solve the above problems.

[0004] A particle detector for a photomask in a lithography machine is used to inspect two sides of a photomask and clean away tiny particles thereon. The particle detector includes a frame, a transport assembly mounted on the frame, at least one cleaning assembly mounted on one side of the transport assembly, and at least two light detector assemblies mounted opposite each other on the frame. The arrangement direction of the two light detector assemblies is perpendicular to the transport direction of the photomask, and they are located on opposite sides of that transport direction. Each light detector assembly includes a housing, a laser emitter disposed within the housing, a galvanometer mounted on one side of the laser emitter, at least two first convex lenses mounted on one side of the galvanometer, a first reflecting mirror mounted on the first convex lens, a second convex lens mounted on one side of the first reflecting mirror, a second reflecting mirror mounted on one side of the second convex lens, at least two third convex lenses mounted on one side of the first convex lens, a third reflecting mirror mounted on one side of the galvanometer, and a light receiver mounted on one side of the third reflecting mirror. The housing has an opening facing another light detector assembly. The laser path emitted by the laser emitter is as follows: laser emitter, galvanometer, first convex lens, first reflector, second convex lens, second reflector, opening, photomask, opening, first reflector, third convex lens, galvanometer, third reflector, and light receiver. The laser emitter emits a laser beam to form a main beam. When the main beam illuminates the photomask, part of the main beam is reflected to form a main reflection line. When the main beam illuminates tiny particles on the photomask, the main beam is reflected to form a diffuse reflection line. The incident angle of the main beam illuminating the photomask is 60°, the angle between the diffuse reflection line and the photomask is 15°, and the angle deviating from the main reflection line is 15°.

[0005] Furthermore, the transport assembly includes a lead screw moving component disposed on the frame, a slide rail disposed opposite to one side of the lead screw moving component, and at least three platforms disposed on the lead screw moving component.

[0006] Furthermore, the length direction of the slide rail is parallel to the arrangement direction of the light detector assembly and the cleaning assembly.

[0007] Furthermore, a receiving opening penetrating the platform body is provided in the center of the platform, and a support block is provided at each of the four corners of the receiving opening.

[0008] Furthermore, the cleaning assembly includes at least two supports disposed opposite to each other on the frame, and at least two air blocks respectively disposed on the two supports.

[0009] Furthermore, the output direction of the two air blowing blocks is toward the material transport direction of the platform, and inclined toward the transport direction of the photomask.

[0010] Furthermore, one of the light detector components is disposed at the output end of a lifting component.

[0011] Furthermore, the galvanometer is positioned at the output end of a servo motor.

[0012] Compared with existing technologies, the particle detector on the photomask of a lithography machine provided by this utility model transports the photomask through the transport assembly, and then sequentially passes it through the cleaning assembly and the light detector assembly. The two light detector assemblies are arranged perpendicular to the length direction of the slide rail and are respectively disposed on both sides of the slide rail, so that the two light detector assemblies can detect both sides of the photomask placed on the stage. The laser emitted by the laser emitter is focused by the first and second convex lenses, which can illuminate particles as small as 10 μm. The light signal is fed back to the light receiver for conversion into different spectra, and the computer analyzes and calculates to obtain the diffuse reflection spectrum and position information of different particle sizes. Finally, based on the particle information obtained by the computer, the photomask is cleaned by the cleaning assembly. The particle detector on the photomask of a lithography machine can detect particles as small as 10 μm, and the entire process requires no manual intervention, is highly automated, and suitable for assembly line production. Attached Figure Description

[0013] Figure 1 This is a schematic diagram of the particle detector on the photomask of a lithography machine provided by this utility model.

[0014] Figure 2 for Figure 1 A schematic diagram of the stage structure of the particle detector on the photomask of a lithography machine.

[0015] Figure 3 for Figure 1 A schematic diagram of the light detector assembly in the particle detector on the photomask of a lithography machine.

[0016] Figure 4 This is a diagram of the laser beam path at the laser emitter.

[0017] Figure 5 This is a diagram of the laser's ray path from another perspective.

[0018] Figure 6 for Figure 1 The image shows the original feedback signal after the particle detector on the photomask of the lithography machine scans.

[0019] Figure 7 for Figure 1 The lithography machine uses a particle detector on the photomask to scan the image before correction.

[0020] Figure 8 for Figure 1 The lithography machine uses a particle detector on the photomask to scan the corrected image.

[0021] Figure 9 for Figure 1 The image of the photomask is scanned by a particle detector on the photomask of the lithography machine.

[0022] Figure Number Explanation: Frame 10, Transport Component 20, Lead Screw Moving Component 21, Slide Rail 22, Platform 23, Reception Port 24, Support Block 25, Cleaning Component 30, Bracket 31, Air Blowing Block 32, Light Detector Component 40, Housing 41, Laser Emitter 42, Galvanometer 43, First Convex Lens 44, First Reflector 45, Second Convex Lens 46, Second Reflector 47, Third Convex Lens 48, Third Reflector 49, Light Receiver 411, Opening 412, Photomask 50, Main Beam 60, Main Reflection Ray 70, Diffuse Reflection Ray 80 Detailed Implementation

[0023] The specific embodiments of this utility model are described in further detail below. It should be understood that the description of the embodiments of this utility model herein is not intended to limit the scope of protection of this utility model.

[0024] like Figure 1 The diagram shown is a structural schematic of the particle detector on a photomask for a lithography machine provided by this utility model. The particle detector includes a frame 10, a transport assembly 20 disposed on the frame 10, at least one cleaning assembly 30 disposed on one side of the transport assembly 20, and at least two light detector assemblies 40 disposed opposite to each other on the frame 10. It is conceivable that the particle detector also includes other functional modules, such as a power supply module, a gas supply module, etc., which are technologies known to those skilled in the art and will not be described in detail here.

[0025] It should be noted that the particle detector on the photomask of the lithography machine is used to inspect both sides of a photomask 50 and clean away any tiny particles on it. The photomask 50, also known as a photolithography mask, is a pattern master used in photolithography processes commonly employed in micro-nano fabrication technology. The main material of the photomask 50 is quartz, a high-quality transparent material with high purity and good optical properties. The photomask 50 itself is existing technology and will not be described in detail here.

[0026] The frame 10 is used to mount the various components so that they can cooperate in various ways to complete the inspection and cleaning of the photomask 50.

[0027] The transport assembly 20 includes a lead screw moving component 21 disposed on the frame 10, a slide rail 22 disposed on one side opposite to the lead screw moving component 21, and at least three platforms 23 disposed on the lead screw moving component 21.

[0028] The lead screw moving component 21 is driven by a transmission motor and can drive the stage 23 to reciprocate along the length direction of the slide rail 22. The length direction of the slide rail 22 is parallel to the arrangement direction of the light detector assembly 40 and the cleaning assembly 30, so that the stage 23 can pass through the light detector assembly 40 and the cleaning assembly 30 in one go, thereby completing the detection and cleaning operations on the photomask 50 placed on the stage 23.

[0029] Please see Figure 2 The stage 23 has a central opening 24 that extends through the stage body. A support block 25 protrudes from each of the four corners of the opening 24. When the photomask 50 is placed on the stage 23, the four support blocks 25 support the four corners of the photomask 50, so that both sides of the photomask 50 can be exposed and detected by the two light detector assemblies 40.

[0030] The cleaning assembly 30 includes at least two supports 31 disposed opposite to each other on the frame 10, and at least two air blocks 32 respectively disposed on the two supports 31.

[0031] Two brackets 31 are used to fix the two air blowing blocks 32. Each of the two air blowing blocks 32 is connected to an air pipe and communicates with an air supply module. The output direction of the two air blowing blocks 32 is towards the material conveying direction of the platform 23 and is inclined to the length direction of the slide rail 22. In this way, when the photomask 50 placed on the platform 32 passes through the cleaning component 30, the gas blown out by the two air blowing blocks 32 can blow away the tiny particles on the photomask 50 in advance.

[0032] The two light detector assemblies 40 are arranged perpendicular to the length direction of the slide rail 22 and are respectively disposed on both sides of the slide rail 22. Thus, when the stage 23 moves on the slide rail 22, it can move between the two light detector assemblies 40, allowing the two light detector assemblies 40 to detect the two sides of the photomask 50 placed on the stage 23. One light detector assembly 40 is fixedly disposed on the frame 10, and the other light detector assembly 40 is disposed at the output end of a lifting component. This lifting component can drive one light detector assembly 40 to move up and down, thereby controlling the distance between the light detector assembly 40 and the photomask 50 to adjust the detection effect.

[0033] Please see Figure 3 The light detector assembly 40 includes a housing 41, a laser emitter 42 disposed within the housing 41, a galvanometer 43 disposed on one side of the laser emitter 42, at least two first convex lenses 44 disposed on one side of the galvanometer 43, a first reflector 45 disposed on the first convex lens 44, a second convex lens 46 disposed on one side of the first reflector 45, a second reflector 47 disposed on one side of the second convex lens 46, at least two third convex lenses 48 disposed on one side of the first convex lens 44, a third reflector 49 disposed on one side of the galvanometer 43, and a light receiver 411 disposed on one side of the third reflector 49.

[0034] The shape of the housing 41 is made according to actual needs, and it can be used to install and mount the various lenses and reflectors mentioned above, so that the laser emitted by the laser emitter 42 can irradiate along the set path.

[0035] The housing 41 has an opening 412 facing another light detector assembly 40. The laser emitted by the laser emitter 42, after reflection and refraction, shines through the opening 412 onto the photomask 50. When the laser shines on tiny particles on the photomask 50, due to the uneven surface of the particles, the laser is reflected, forming diffuse reflection light. This light is then reflected and refracted through the opening 412 and received by the light receiver 411. The light receiver 411 converts the light signal into different spectra and uses a computer to analyze and calculate the diffuse reflection spectrum and position information of particles of different sizes. The working principles of the laser emitter 42 and the light receiver 411 are existing technologies and will not be described in detail here.

[0036] The output direction of the laser emitter 42 is towards the galvanometer 43, and the plane of the reflective surface of the galvanometer 43 is inclined with respect to the output direction of the laser emitter 42. The galvanometer 43 is located at the output end of a servo motor 431, and the galvanometer 43 can be oscillated at high speed by the servo motor 431, so that the laser reflected by the galvanometer 43 forms a cycloid.

[0037] The mirror length directions of the first, second, and third convex lenses 44, 46, and 48 are all parallel to the mirror length directions of the first and second reflecting mirrors 45 and 47, and this direction is parallel to the output direction of the laser emitter 42. Thus, the laser light reflected by the galvanometer 43 can intersect with the mirror surfaces of the first, second, and third convex lenses 44, 46, and 48, as well as the first and second reflecting mirrors 45 and 47, thereby allowing the laser light to pass through the first, second, and third convex lenses 44, 46, and 48 or to irradiate the mirror surfaces of the first and second reflecting mirrors 45 and 47.

[0038] Please see Figure 4 and Figure 5 The laser emitter 42 emits a laser beam to form a main beam 60. When the main beam 60 shines on the photomask 50, a portion of the main beam 60 is transmitted through the photomask 50 and reflected away, while the other portion is reflected to form a main reflection ray 70. When the main beam 60 shines on tiny particles on the photomask 50, the main beam 60 is reflected to form a diffuse reflection ray 80. Since the surface of the photomask 50 is smooth, it can be considered as a mirror. According to the law of reflection, the reflected ray, the incident ray, and the normal all lie in the same plane, the reflected ray and the incident ray are on opposite sides of the normal, and the angle of incidence is equal to the angle of reflection. The main beam 60 and the main reflected line 70 have the same normal angle relative to the plane of the photomask 50. Therefore, the angle of reflection of the main reflected line 70 can be determined by the incident angle of the main beam 60, thus fixing the path of the main reflected line 70. This avoids interference from various mirrors inside the light detector assembly 40, preventing the main reflected line 70 from falling into a light trap, i.e., the main reflected line 70 irradiating the inner wall of the housing 41. According to experiments, an incident angle of 60° when the main beam 60 irradiates the photomask 50 is optimal, ensuring that the main reflected line 70 does not irradiate the various mirrors inside the light detector assembly 40.

[0039] According to the definition of diffuse reflection, the smaller the deviation angle of the diffuse reflection line 80, the stronger the light signal and the more obvious the particle resolution effect. However, a smaller deviation angle also results in a large amount of interference stray light, and the design of the detector's internal structure cannot be realized. Therefore, the principle for determining the diffuse reflection line 80 is based on eliminating interference stray light, avoiding structural interference, and facilitating processing and installation. According to experimental results, the angle between the diffuse reflection line 80 and the photomask 50 is 15°, and the angle of deviation from the main reflection line 70 is 15°. At this angle, the diffuse reflection line 80, without structural interference, enters the light receiver 411 with a relatively strong light signal compared to other diffuse reflection lines 80.

[0040] The laser path emitted by the laser emitter 42 is as follows: the main beam 60 emitted by the laser emitter 42 illuminates the galvanometer 43 and forms a cycloid through the galvanometer 43. Then, the main beam 60 illuminates two first convex lenses 44 successively, and the light converges after passing through the two first convex lenses 44. Then, it is reflected by the first reflector 45 to the second convex lens 46, and further converged by the second convex lens 46. Then, the main beam 60 is reflected by the second reflector 47 and illuminates the photomask 50 through the opening 412. When the main beam 60 illuminates the photomask 50, part of the main beam 60 is reflected to form the main reflection line 70, which illuminates the inner wall of the housing 41. When the main beam 60 illuminates the tiny particles on the photomask 50, the diffuse reflection line 80 is formed. This diffuse reflection line 80 illuminates the first reflector 45 through the opening 412, and is reflected by the first reflector 45 to the third convex lens 48. The light then converges after passing through two third convex lenses 48, and then illuminates the galvanometer 43. The galvanometer 43 reflects the light to the third reflector 49, and the third reflector 49 illuminates the light receiver 411. Finally, the light receiver 411 converts the signal of the diffuse reflection line 80 into different spectra, and uses a computer to analyze and calculate the diffuse reflection spectrum and position information of different particle sizes. Finally, based on the particle information obtained by the computer, the photomask 50 is transported back to the cleaning assembly 30 for gas purging to clean the surface of the photomask 50, and then sent between the two light detector assemblies 40 for detection. The above steps are repeated until no particles are detected on the surface of the photomask 50.

[0041] The light detector assembly 40 is pre-tested with standard spherical particles of 10um, 20um, 30um, 50um, and 100um. That is, standard spherical particles of 10um, 20um, 30um, 50um, and 100um are purchased first, and the system is used to detect the signals of particles of different sizes to record their signal intensity, thereby establishing the relationship between particle size and signal intensity, and determining the particle size based on this calibration data.

[0042] Please see Figures 6 to 8 Because a progressive scan with a scanning rate of 70Hz is used, each particle is scanned by the laser at least three times. Due to the inherent sensitivity of the galvanometer 43, there is a slight deviation between its actual position and the control signal. However, the galvanometer 43 will provide feedback on its actual position, and this characteristic is constant. Based on this characteristic, the scanned points are aligned to the physical positions corresponding to the feedback voltage, thus correcting the distortion. Based on this position correction, the size of the photomask 50 is fixed. From an image perspective, it has a clear boundary. The boundary of the photomask 50 is obtained through image detection. The collected points are mapped to the physical positions of the photomask 50. A binary transformation is performed on all scanned points; values ​​below the background energy are set to 0, and values ​​above the background energy are set to 1. Continuous detection of all points yields the area encircling the particle and the total energy value, thus determining the particle size. Figure 9 The image of particles on the photomask 50 is scanned by a particle detector on the photomask of the lithography machine, wherein the yellow particles are the particles on the photomask 50.

[0043] The laser emitted by the laser emitter 42 is focused by the first and second convex lenses 44 and 46, capable of illuminating particles as small as 10 μm, and the light signal is fed back to the light receiver 411. Following the working principle of the light detector assembly 40, it also has the function of reading QR codes or barcodes and can upload data to a computer.

[0044] Compared with the prior art, the particle detector on the photomask of the lithography machine provided by this utility model transports the photomask 50 through the transport assembly 20 and sequentially passes it through the cleaning assembly 30 and the light detector assembly 40. The two light detector assemblies 40 are arranged perpendicular to the length direction of the slide rail 22 and are respectively disposed on both sides of the slide rail 22, so that the two light detector assemblies 40 can detect the two sides of the photomask 50 placed on the stage 23. The laser emitted by the laser emitter 42 is focused by the first and second convex lenses 44 and 46, which can illuminate particles as small as 10 μm in size. The light signal is fed back to the light receiver 411 for conversion into different spectra, and the computer analyzes and calculates to obtain the diffuse reflection spectrum and position information of different particle sizes. Finally, based on the particle information obtained by the computer, the photomask 50 is cleaned by the cleaning assembly 30. The particle detector on the photomask of the lithography machine can detect particles as small as 10µm, and the entire process requires no manual intervention, making it highly automated and suitable for assembly line production.

[0045] The above are merely preferred embodiments of the present utility model and are not intended to limit the scope of protection of the present utility model. Any modifications, equivalent substitutions or improvements within the spirit of the present utility model are covered within the scope of the claims of the present utility model.

Claims

1. A particle detector for a photomask in a lithography machine, used to inspect two sides of a photomask and clean away tiny particles thereon, characterized in that: The particle detector on the photomask for the lithography machine includes a frame, a transport assembly mounted on the frame, at least one cleaning assembly mounted on one side of the transport assembly, and at least two light detector assemblies mounted opposite each other on the frame. The arrangement direction of the two light detector assemblies is perpendicular to the transport direction of the photomask, and they are located on opposite sides of the transport direction. Each light detector assembly includes a housing, a laser emitter mounted inside the housing, a galvanometer mounted on one side of the laser emitter, at least two first convex lenses mounted on one side of the galvanometer, a first reflecting mirror mounted on the first convex lens, a second convex lens mounted on one side of the first reflecting mirror, a second reflecting mirror mounted on one side of the second convex lens, at least two third convex lenses mounted on one side of the first convex lens, and a third reflecting mirror mounted on one side of the galvanometer. A light receiver is disposed on one side of the third reflector. The housing has an opening facing another light detector assembly. The laser path emitted by the laser emitter is as follows: laser emitter, galvanometer, first convex lens, first reflector, second convex lens, second reflector, opening, photomask, opening, first reflector, third convex lens, galvanometer, third reflector, light receiver. The laser emitter emits a laser to form a main beam. When the main beam illuminates the photomask, part of the main beam is reflected to form a main reflection line. When the main beam illuminates tiny particles on the photomask, the main beam is reflected to form a diffuse reflection line. The incident angle of the main beam illuminating the photomask is 60°. The angle between the diffuse reflection line and the photomask is 15°, and the angle deviating from the main reflection line is 15°.

2. The particle detector on the photomask of a lithography machine according to claim 1, characterized in that: The transport assembly includes a lead screw moving component mounted on the frame, a slide rail disposed opposite to one side of the lead screw moving component, and at least three platforms mounted on the lead screw moving component.

3. The particle detector on the photomask of a lithography machine according to claim 2, characterized in that: The length direction of the slide rail is parallel to the arrangement direction of the light detector assembly and the cleaning assembly.

4. The particle detector on the photomask of a lithography machine according to claim 2, characterized in that: The platform has a through-hole in the center, and a support block protrudes from each of the four corners of the through-hole.

5. The particle detector on the photomask of a lithography machine according to claim 2, characterized in that: The cleaning assembly includes at least two supports disposed opposite to each other on the frame, and at least two air blocks disposed on the two supports respectively.

6. The particle detector on the photomask of a lithography machine according to claim 5, characterized in that: The output direction of the two air blowing blocks is toward the material transport direction of the platform and is inclined toward the transport direction of the photomask.

7. The particle detector on the photomask of a lithography machine according to claim 1, characterized in that: One of the light detector components is disposed at the output of a lifting component.

8. The particle detector on the photomask of a lithography machine according to claim 1, characterized in that: The galvanometer is located at the output end of a servo motor.

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