A proximity contact exposure device
By setting a small exposure field of view in a proximity contact exposure device and using a stepping or scanning motion device to adjust the relative position of the mask and the substrate, the problem of insufficient resolution and overlay accuracy of traditional proximity contact exposure machines is solved, and higher processing accuracy and overlay accuracy are achieved.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- 智慧星空(上海)工程技术有限公司
- Filing Date
- 2022-11-28
- Publication Date
- 2026-07-31
AI Technical Summary
Traditional proximity exposure machines have insufficient exposure resolution and overlay accuracy, limiting their use to low-precision applications and products.
In traditional proximity exposure apparatuses, an exposure illumination field smaller than the area to be exposed on the substrate is set, and the illumination system is moved relative to the mask and substrate stage by a stepping or scanning motion device. Combined with a vertical measurement and alignment system, local stepping or scanning exposure is achieved, and the relative position of the mask and substrate is adjusted in real time.
It improves the exposure resolution to below 3µm and the overlay accuracy to below 1µm, making it suitable for mask-substrate combinations of different relative sizes and improving processing accuracy and overlay accuracy.
Smart Images
Figure CN115857281B_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of semiconductor processing equipment technology, and specifically relates to a proximity contact exposure device. Background Technology
[0002] Exposure machines employ a technique similar to photo printing, transferring the fine patterns on a photomask onto a silicon wafer, substrate, or printed circuit board (hereinafter collectively referred to as: substrate) through light exposure. Exposure machines are generally classified into: proximity contact exposure machines, laser direct-write exposure machines, stepper projection exposure machines, and scanning projection exposure machines. The substrate can be a silicon wafer, compound wafer, wafer-level or flat glass, wafer-level or flat molded material (mold compound wafer or plate), solar cell substrate, or printed circuit board, etc.
[0003] Proximity lithography employs both contact and non-contact (proximity) methods. Contact lithography involves direct contact between the photomask and the photoresist, resulting in a pattern on the photoresist that is identical to the photomask. Proximity lithography, on the other hand, leaves a very small gap (typically 0–500 μm) between the photomask and the photoresist during the exposure process. Both exposure methods have their advantages and disadvantages. When using contact exposure, the mask and photoresist are in direct contact, and the exposure resolution can reach 0.8μm-2μm, but it is easy to damage the mask and contaminate the photoresist. When using proximity exposure, although the damage to the mask and contamination of the photoresist are mitigated depending on the size of the gap between the mask and the photoresist, the diffraction of light will cause the pattern resolution projected from the mask onto the photoresist to decrease. The resolution of proximity exposure is 2μm when the gap between the mask and the photoresist is 0-10μm, and the resolution of proximity exposure is 3μm or more when the gap between the mask and the photoresist is greater than 10μm. Moreover, traditional proximity contact exposure machines often use one alignment and one exposure to achieve pattern exposure, so it is difficult to achieve an overlay accuracy of less than 1μm. The accuracy is relatively low, which means that proximity contact exposure machines can only be used for low-precision applications and low-precision products. Summary of the Invention
[0004] In view of this, the present invention proposes a proximity-contact exposure device for improving exposure resolution and overlay accuracy. Based on a traditional proximity-contact exposure device, an exposure illumination field of view smaller than the area to be exposed on the substrate is set up. Simultaneously, a stepping or scanning motion device is provided to support the mask stage and substrate stage, or to support the illumination system. After the mask and substrate are focused, leveled, and aligned, the illumination system is moved relative to the mask stage and substrate stage by driving the aforementioned stepping or scanning motion device, thereby completing the full-film exposure of the substrate. This movement can be a stepping-style, one-exposure-field-by-exposure partitioning exposure, or a full-pattern area scanning exposure. The present invention can support complete exposure of the substrate even when the field of view of the exposure light source is smaller than the area to be exposed on the substrate, thus allowing for more precise exposure light sources and improving the resolution of proximity-contact exposure to below 3µm. The present invention uses partial stepping or scanning exposure, rather than simultaneous full exposure, therefore, during the stepping or scanning exposure process, the relative position of the mask and substrate can be finely adjusted in real time by the mask stage or substrate stage, improving the overlay accuracy to below 1µm.
[0005] To achieve the above-mentioned technical objectives, the specific technical solution adopted by the present invention is as follows:
[0006] A proximity-contact exposure device, comprising: An illumination system used to provide an exposure light source during proximity or contact exposure processes; Alignment system is used to align the corresponding alignment marks on the mask and the substrate; A vertical measurement system is used to measure the vertical height and parallelism of the lower surface of the mask relative to the upper surface of the substrate. A mask mounting platform, positioned opposite the lighting system, is used to mount the mask. A substrate stage, positioned opposite the photomask, is used to mount the substrate; The proximity exposure device uses the illumination system to illuminate the mask on the mask stage, thereby exposing the pattern on the mask to the substrate coated with photoresist on the substrate stage in a proximity or contact manner. The illumination system is mounted on a stepping or scanning motion device, or the mask stage and the substrate stage are mounted as a whole on the stepping or scanning motion device; the stepping or scanning motion device is used to make the mask stage and the substrate stage move in a stepping or scanning plane perpendicular to the exposure light source relative to the illumination system. The field of view of the exposure light source is smaller than the area of the substrate to be exposed, and the exposure process is either scanning exposure or step-by-step exposure.
[0007] Furthermore, the substrate stage is a substrate motion stage; the substrate motion stage is used to adjust the pose of the substrate, to align the substrate with the mask, and to adjust the position in real time during the exposure process.
[0008] Furthermore, the exposure process includes the following steps: S101: The vertical measurement system measures the vertical distance and tilt deviation between the substrate and the mask, and adjusts the vertical distance and tilt deviation to the pre-alignment position by means of the substrate motion stage; S102: The alignment system measures the horizontal positional deviation of the substrate relative to the mask, and adjusts the overall positional deviation between the substrate and the mask by means of the substrate motion stage; S103: The stepping or scanning motion device drives the mask stage and the substrate stage to perform stepping or scanning planar motion relative to the exposure light source. At the same time, the substrate motion stage makes real-time fine adjustments to reduce the horizontal positional deviation between the pattern on the substrate and the pattern on the mask within the exposure field of view, until all areas of the substrate to be exposed are exposed.
[0009] Furthermore, the graphic area of the mask is smaller than the area to be exposed on the substrate; the mask stage is a mask motion stage; the mask motion stage is used to drive the mask to make planar movements perpendicular to the exposure light source.
[0010] Furthermore, the exposure process includes the following steps: S201: The vertical measurement system measures the vertical distance and tilt deviation between the substrate and the mask, and adjusts the vertical distance and tilt deviation to the pre-aligned position by means of the substrate motion stage; S202: The alignment system measures the horizontal positional deviation of the substrate relative to the mask, and reduces the overall positional deviation between the first exposure area of the substrate and the mask by means of the substrate motion stage; S203: The stepping or scanning motion device drives the mask stage and the substrate stage to perform stepping or scanning planar motion relative to the exposure light source. At the same time, the substrate motion stage makes real-time fine adjustments to reduce the horizontal positional deviation between the pattern on the substrate and the pattern on the mask within the exposure field of view, until the first region of the substrate is exposed. S204: Based on the movement of the mask stage and / or the stepping or scanning motion device, align the second exposure area of the substrate with the mask; then repeat steps S201 to S203 to expose the second area of the substrate. ... Based on the movement of the mask stage and / or the stepping or scanning motion device, the nth region of the substrate is aligned with the mask; then, steps S201 to S203 are repeated to expose the nth region of the substrate. Exposure is completed for all areas of the substrate to be exposed.
[0011] Furthermore, both the vertical measurement system and the alignment system employ a face-to-face measurement method, inserted between the substrate and the mask, to measure the relative pose of the mask and the substrate.
[0012] Furthermore, the alignment system includes two sets of alignment lenses with their optical axes aligned on the same straight line and their shooting directions opposite; the vertical measurement system includes two sets of vertical measurement sensors with their axes aligned on the same straight line and their measurement directions opposite; the alignment system and the vertical measurement system are integrated into a comprehensive measurement system, which is driven by the measurement system's motion stage to perform planar motion, and its travel covers all graphic areas of the mask; multiple pairs of alignment marks are provided on both the mask and the substrate; the alignment system is used to measure multiple sets of alignment marks on the mask and the substrate, and after calculation, obtains the horizontal positional offset and higher-order graphic distortion error between the mask and the substrate; the vertical measurement system is used to measure the vertical positional deviation between multiple points on the mask and the substrate, and after calculation, obtains the vertical positional deviation between the mask and the substrate and the vertical surface shape error of the substrate.
[0013] Furthermore, in S101, S102 or S201, S202, the process of initial alignment and attitude adjustment between the substrate and the mask specifically includes the following steps: S301: Set the mask and the substrate at a first relative height; measure the first relative pose between the mask and the substrate based on the measurement system; S302: Set the mask and the substrate at a relative exposure height; measure the second relative horizontal pose between the mask and the substrate based on two fixed alignment cameras; S303: Calculate the pose deviation between the mask and the substrate at the relative exposure height based on the first relative pose and the second relative horizontal pose; S304: The substrate is moved by the substrate motion stage to eliminate the pose deviation.
[0014] Furthermore, the area of the patterned area of the mask is smaller than the area to be exposed on the substrate, and is the same as the field of view of the illumination system; the illumination system is fixed to the mask position and mounted on the mask stage; the vertical measurement system includes an upward vertical measurement sensor and a downward vertical measurement sensor; the alignment system includes an upward alignment camera and a downward alignment camera; alignment marks are provided on both the mask and the substrate; the downward vertical measurement sensor and the downward alignment camera are mounted on the mask stage, and the upward vertical measurement sensor and the upward alignment camera are mounted on the substrate stage; the vertical measurement system measures the vertical relative pose between the mask and the substrate; the alignment system measures the horizontal relative pose between the mask and the substrate based on the alignment marks captured by the upward alignment camera and the downward alignment camera.
[0015] Furthermore, the exposure process includes the following steps: S401: Set the mask stage at the mask measurement height; measure the horizontal and vertical pose of the mask based on the upward vertical measurement sensor and the upward alignment camera; S402: Move the mask stage to the first region position of the substrate, and set the mask stage at the substrate measurement height; measure the vertical and horizontal pose of the first region of the substrate based on the downward vertical measurement sensor and the downward alignment camera; S403: Calculate the pose deviation of the first region of the mask and the substrate in terms of relative exposure height based on the measurement results in steps S401 and S402; S404: The substrate is moved by the substrate motion stage to eliminate the pose deviation calculated in step S403; S405: Turn on the lighting system to complete the exposure of the first region of the substrate; Repeat steps S402 to S404 to complete the exposure of the second region of the substrate; … Repeat steps S402 to S404 to complete the exposure of the nth region of the substrate; Exposure is completed for all areas of the substrate to be exposed.
[0016] By adopting the above technical solution, the present invention can also bring the following beneficial effects: This invention proposes two exposure methods: scanning exposure and step-by-step zone exposure, making the proximity exposure device of this invention applicable to mask-substrate combinations of different relative sizes; using small-sized masks can also achieve higher mask pattern processing accuracy at a lower cost; This invention proposes a technical solution for mask-substrate alignment based on dual alignment cameras with opposite shooting directions. This solution aligns multiple sets of alignment marks on the mask-substrate across the entire graphic area of the mask, thereby calculating higher-order errors such as magnification and distortion, in addition to the overall translational and rotational errors of the mask relative to the substrate. Through minor adjustments to the substrate stage during stepping or scanning exposure, the overlay accuracy is effectively improved. When equipped with additional reference marks and an online error correction alignment camera, it can also effectively eliminate horizontal positional errors generated during the downward movement of the mask to the exposure height. Attached Figure Description To more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.
[0017] Figure 1 This is an exploded view of a proximity exposure device according to a specific embodiment of the present invention; Figure 2 This is a schematic diagram of the area to be exposed on the substrate during partitioned exposure in a specific embodiment of the present invention; Figure 3 This is a schematic diagram of an exposure path and exposure field on a substrate during scanning exposure in a specific embodiment of the present invention; Figure 4 This is a schematic diagram illustrating various selectable exposure fields during scanning exposure in a specific embodiment of the present invention; The components include: base-1; substrate stage-2; suction cup-3; substrate-4; stepping or scanning motion device-5; mask stage-6; mask plate-7; upper alignment camera-8; lighting system-9; lower alignment camera-10; exposure field of view-11; and exposure path-12. Detailed Implementation
[0018] The embodiments of the present invention will now be described in detail with reference to the accompanying drawings.
[0019] The following specific examples illustrate the implementation of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them. The present invention can also be implemented or applied through other different specific embodiments, and the details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention. It should be noted that, in the absence of conflict, the following embodiments and features in the embodiments can be combined with each other. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.
[0020] It should be noted that various aspects of embodiments within the scope of the appended claims are described below. It will be apparent that the aspects described herein can be embodied in a wide variety of forms, and any particular structure and / or function described herein is merely illustrative. Based on this invention, those skilled in the art will understand that one aspect described herein can be implemented independently of any other aspect, and two or more of these aspects can be combined in various ways. For example, any number of aspects set forth herein can be used to implement the device and / or practice the method. Additionally, this device and / or method can be implemented using other structures and / or functionalities besides one or more of the aspects set forth herein.
[0021] It should also be noted that the illustrations provided in the following embodiments are only schematic representations of the basic concept of the present invention. The drawings only show the components related to the present invention and are not drawn according to the actual number, shape and size of the components in the actual implementation. In the actual implementation, the form, quantity and proportion of each component can be arbitrarily changed, and the layout of the components may also be more complex.
[0022] Furthermore, specific details are provided in the following description to facilitate a thorough understanding of the examples. However, those skilled in the art will understand that the described aspects can be practiced without these specific details.
[0023] In one embodiment of the present invention, a proximity-contact exposure device is proposed, such as... Figure 1 As shown, it includes: Lighting system 9 is used to provide an exposure light source during proximity or contact exposure processes; The alignment system includes an upper alignment camera 8 and a lower alignment camera 10, used to align the corresponding alignment marks on the mask and the substrate. A vertical measurement system is used to measure the vertical height and parallelism of the lower surface of the mask relative to the upper surface of the substrate. A mask plate 7 mounting platform is set opposite to the lighting system 9 and is used to mount the mask plate 7; The substrate stage 2, positioned opposite the mask 7, is used to mount the substrate; Among them, the proximity contact exposure device is based on the illumination system 9 illuminating the mask 7 on the mask stage 6, and exposing the pattern on the mask 7 to the substrate coated with photoresist on the substrate stage 2 in a proximity or contact manner. The mask stage 6 and substrate stage 2, or the illumination system 9, are mounted on a stepping or scanning motion device 5; the stepping or scanning motion device 5 is used to make the mask stage 6 and substrate stage 2 move in a stepping or scanning plane perpendicular to the exposure light source relative to the illumination system 9. The field of view 11 of the exposure light source is smaller than the area of the substrate to be exposed, and the exposure process is either scanning exposure or step-by-step exposure.
[0024] In this embodiment, the substrate stage 2 is a substrate motion stage; the substrate motion stage is used to adjust the pose of the substrate, realize the alignment of the substrate 4 and the mask 7, and adjust the position in real time during the exposure process.
[0025] In traditional proximity-contact exposure devices, the exposure field of view 11 of the illumination system 9 is the same as the effective pattern area size of the mask 7 and the size of the area of the substrate to be exposed, thus completing the full exposure of the substrate in a single illumination. In this embodiment, the exposure field of view 11 of the illumination system 9 is smaller than the size of the area of the substrate to be exposed, therefore, it is impossible to complete the full exposure of the substrate in a single illumination. Therefore, this embodiment adds a stepping or scanning motion device 5 or a scanning stage to the traditional proximity-contact exposure device. By providing horizontal stepping or scanning motion, after the mask 7 and substrate 4 have completed focusing, leveling, and alignment, the mask 7 and substrate 4 move relative to the illumination system 9 to complete the full exposure of the substrate. The effective pattern area size of the mask 7 can be the same as the size of the area to be exposed of the substrate 4, in which case the substrate is exposed as a whole; or the effective pattern area size of the mask 7 can be smaller than the size of the area to be exposed of the substrate 4, in which case the substrate is exposed in sections, such as... Figure 2 As shown. Each area to be exposed on the substrate can be exposed sequentially, one exposure field at a time, using a step exposure method, or it can be exposed based on exposure path 12, completing the exposure of an entire substrate area, as shown. Figure 3 As shown. Since step or scan exposures require stitching the exposure fields of view, the exposure field of view 11 needs to be equipped with features that enable stitching, such as... Figure 4As shown. Simultaneously, by adjusting the vertical relative pose of the mask 7 and substrate 4 in real time based on the substrate motion stage during stepping or scanning exposure, the vertical position accuracy of the mask 7 and substrate 4 during exposure is precisely controlled to improve exposure quality; the horizontal relative position of the mask 7 and substrate 4 is adjusted and precisely controlled in real time to improve exposure overlay accuracy.
[0026] A schematic diagram of the basic structure of the proximity exposure device in this embodiment is shown below. Figure 1 As shown, it mainly consists of several parts, including an illumination system 9 (containing a light source, shutter, and reflector), a mask stage 6, a mask plate 7, a stepping or scanning motion device 5, a base 1, a substrate stage 2, a suction cup 3, a substrate (silicon wafer / PCB, etc.), an upper alignment camera 8 and a moving-in / out mechanism, a lower alignment camera 10, a vertical measurement system, a substrate transfer system, and a mask transfer system.
[0027] In this embodiment of the device, the light source of the lighting system 9 is a mercury lamp, an LED, or a laser.
[0028] The shutter system controls the opening and closing of the light source. After passing through the shutter, the illumination light is homogenized into parallel illumination light by the light homogenizing system, and then shines onto the mask 7 after passing through a mirror or other optical lenses in the illumination optical path system. The mask 7 is supported or attached to the mask stage 6. Before exposure, the mask stage 6 adjusts the position and orientation of the mask 7 through a six-degree-of-freedom motion mechanism. The substrate is placed and attached to the suction cup 3, and its position and orientation are adjusted by the six-degree-of-freedom motion mechanism of the substrate stage 2. When the exposure begins, the illumination system 9 opens the shutter, and the exposure light shines onto the photoresist on the substrate after passing through the mask 7, exposing the photoresist coated on the substrate surface.
[0029] The vertical measurement system measures the distance between the upper surface of the substrate and the lower surface of the mask 7 using a focusing and leveling sensor, and levels the substrate and mask 7 accordingly, and controls the gap between them.
[0030] The upper alignment camera 8 or the lower alignment camera 10 refers to establishing a precise coordinate relationship between the substrate and the mask pattern by measuring the mask surface marks and substrate marks on the mask plate 7 separately or simultaneously using alignment sensors. The alignment system can use image recognition or grating recognition for signal measurement and extraction. The upper alignment camera 8 is used when there are alignment marks on the upper surface of the substrate: after the substrate is transported to the working area, the upper alignment camera 8 establishes a positional relationship between the substrate and the mask plate 7. The lower alignment camera 10 is used when there are alignment marks on the lower surface of the substrate: before the substrate is transported to the working area, the lower alignment camera 10 first obtains the coordinate position of the mask plate 7, then transports the substrate to the working position, and the lower alignment camera 10 obtains the coordinate position of the substrate again, thereby establishing a positional relationship between the substrate and the mask plate 7. If the upper alignment camera 8 is used, a moving-in and moving-out mechanism is required to ensure that the upper alignment camera 8 does not affect the exposure optical path. In addition, some proximity exposure machines use a bidirectional lens alignment system that can simultaneously measure both the mask 7 and the silicon wafer by installing a lens alignment system between the mask 7 and the substrate. This alignment system also needs to have a moving-in and moving-out mechanism to ensure that the alignment system does not affect the exposure optical path.
[0031] In this embodiment, both the substrate stage 2 and the mask stage 6 are driven by motors to achieve multi-degree-of-freedom (XYZRxRyRz) motion in the horizontal and vertical directions. The substrate stage 2 uses XYZRxRyRz multi-degree-of-freedom motion to adjust the suction cup 3 and the substrate 4 on it, and the mask stage 6 uses XYZRxRyRz multi-degree-of-freedom motion to adjust the mask 7.
[0032] In this embodiment, the substrate transfer system is used to automatically load and unload substrates for the exposure machine; the mask 7 transfer system is used to automatically load and unload mask 7 for the exposure machine. When the exposure machine uses manual or semi-automatic loading and unloading of substrates or mask 7, a fully automatic substrate transfer system or mask 7 transfer system is not required.
[0033] In some embodiments, the size of the pattern area of the mask 7 is the same as the size of the exposure area of the substrate, and the illumination field of view used for exposure is smaller than the size of the pattern area of the mask 7 or the size of the exposure area of the substrate. When exposure is performed in step mode, the stepping or scanning motion device 5 drives the mask stage 6 and the substrate stage 2 to move in step relative to the illumination system 9, completing the exposure of the entire area of the substrate that needs to be exposed in one exposure field at a time. At the same time, during each exposure field step exposure, the relative displacement between the mask stage 6 and the substrate stage 2 is driven, thereby adjusting the relative position of the mask 7 and the substrate in real time to compensate for the overlay misalignment caused by factors such as substrate expansion and contraction deformation, thereby improving the overlay accuracy of the proximity contact exposure machine. When using scanning mode for exposure, the scanning stage drives the mask stage 6 and substrate stage 2 to scan relative to the illumination system 9. Exposure of the entire substrate area requires reciprocating scanning exposure. Simultaneously, during scanning exposure, the relative displacement of the mask stage 6 and substrate stage 2 is adjusted in real time, thereby adjusting the relative position of the mask 7 and substrate to compensate for overlay misalignment caused by substrate deformation and other factors, thus improving the overlay accuracy of the near-contact exposure machine. In scanning exposure mode, considering that the exposure field of view 11 needs to be stitched during reciprocating scanning to avoid sudden changes in local exposure energy in overlapping areas and ensure uniform exposure energy across the entire film, the illumination field of view for scanning exposure generally adopts the following configuration: Figure 3 , 4 The exposure field of view 11 shown has a smooth transition feature, such as a rotated rectangle, a rotated square, a hexagon, a rhombus, a parallelogram, a triangle, a trapezoid, etc. The morphological features of the scanned stitching area all have a smooth transition gradient feature.
[0034] Existing proximity exposure machines support both single-sided alignment and exposure, as well as double-sided alignment and exposure. The related technologies are all well-known and are not limited in this embodiment.
[0035] In this embodiment, the exposure process includes the following steps: S101: The vertical measurement system measures the vertical spacing and tilt deviation between the substrate 4 and the mask 7, and adjusts them into position using the substrate motion stage; S102: The alignment system measures the horizontal positional deviation of the substrate 4 relative to the mask 7, and adjusts the overall positional deviation between the substrate 4 and the mask 7 by means of the substrate motion stage; S103: The stepping or scanning motion device 5 drives the mask stage 6 and the substrate stage 2 to perform stepping or scanning planar motion relative to the exposure light source. At the same time, the substrate motion stage makes fine adjustments according to the horizontal positional deviation between the pattern on the substrate and the pattern on the mask within the exposure field of view, until all areas of the substrate to be exposed are exposed.
[0036] In one embodiment, the graphic area of the mask is smaller than the area to be exposed on the substrate; the mask stage 6 is a motion stage for the mask 7; the motion stage for the mask 7 is used to drive the mask 7 to perform planar motion perpendicular to the exposure light source.
[0037] In this embodiment, the exposure process includes the following steps: S201: The vertical measurement system measures the vertical distance and tilt deviation between the substrate and the mask, and adjusts them into position using the substrate motion stage; S202: The alignment system measures the horizontal positional deviation of the substrate relative to the mask, and adjusts the overall positional deviation between the first region of the substrate and the mask by using the substrate motion stage; S203: The stepping or scanning motion device drives the mask stage and substrate stage to perform stepping or scanning planar motion relative to the exposure light source. At the same time, the substrate motion stage makes fine adjustments based on the horizontal positional deviation between the pattern on the substrate and the pattern on the mask within the exposure field of view, until the first area of the substrate is exposed. S204: Based on the movement of the mask 7 stage and / or the stepping or scanning motion device 5, the second region of the substrate is aligned with the mask; then the steps of S201 to S203 are repeated to expose the second region of the substrate. ... Based on the movement of the mask 7 motion stage and / or the stepping or scanning motion device 5, the nth region of the substrate is aligned with the mask; then the steps of S201 to S203 are repeated to expose the nth region of the substrate. Exposure is completed for all areas of the substrate to be exposed.
[0038] In one embodiment, the vertical measurement system and alignment system in the proximity contact exposure apparatus both employ a face-to-face measurement method, inserted between the substrate and the mask, to measure the relative pose of the mask 7 and the substrate.
[0039] In this embodiment, the alignment system includes two sets of alignment lenses with their optical axes aligned on the same straight line and their shooting directions opposite; the vertical measurement system includes two sets of vertical measurement sensors with their axes aligned on the same straight line and their measurement directions opposite; the alignment system and the vertical measurement system are integrated into a comprehensive measurement system, which can be driven by the measurement system's motion stage to perform planar motion, and its travel covers all graphic areas of the mask; multiple pairs of alignment marks are provided on both the mask 7 and the substrate; the alignment system can measure multiple sets of alignment marks on the mask 7 and the substrate, and calculate the horizontal positional offset and higher-order graphic distortion errors between the mask and the substrate; the vertical measurement system can measure the vertical positional deviation between multiple points on the mask and the substrate, and calculate the vertical positional deviation between the mask and the substrate and the vertical surface shape error of the substrate.
[0040] In this embodiment, the process of initial alignment and attitude adjustment between the substrate and the mask 7 in S101, S102 or S201, S202 specifically includes the following steps: S301: Set the mask 7 and the substrate 4 at a first relative height; measure the first relative pose between the mask 7 and the substrate based on the measurement system; S302: Set the mask 7 and the substrate 4 at the second relative height, i.e., the exposure relative height; measure the second relative horizontal pose between the mask 7 and the substrate based on two sets of fixed alignment cameras; S303: Calculate the pose deviation between the mask 7 and the substrate at the relative exposure height based on the first relative pose and the second relative pose; S304: The substrate is moved by a substrate motion stage to eliminate pose deviation.
[0041] This embodiment proposes a technical solution for aligning a mask 7 with a substrate based on dual alignment cameras with opposite shooting directions. This solution aligns multiple sets of alignment marks on the mask-substrate across the entire graphic area of the mask, thereby calculating higher-order errors such as magnification and distortion, in addition to the overall translation and rotation errors of the mask relative to the substrate. Through minor adjustments to the substrate stage during stepping or scanning exposure, the overlay accuracy is effectively improved. Furthermore, when equipped with additional reference marks and an online error correction alignment camera, the horizontal positional error generated during the downward movement of the mask to the exposure height can also be effectively eliminated. In one embodiment, the mask pattern area is smaller than the area of the substrate to be exposed and is the same size as the field of view of the illumination system; the illumination system 9 and the mask position are fixed and both are mounted on the mask stage 6; the vertical measurement system includes an upward vertical measurement sensor and a downward vertical measurement sensor; the alignment system includes a downward alignment camera 8 and an upward alignment camera 10; alignment marks are provided on both the mask 7 and the substrate; the downward vertical measurement sensor and the downward alignment camera 8 are mounted on the mask stage 6, and the upward vertical measurement sensor and the upward alignment camera 10 are mounted on the substrate stage 2; the vertical measurement system measures the vertical relative pose between the mask and the substrate; the alignment system measures the horizontal relative pose between the mask 7 and the substrate based on the alignment marks captured by the downward alignment camera 8 and the upward alignment camera 10.
[0042] In this embodiment, the exposure process includes the following steps: S401: Set the mask stage 6 at the mask measurement height; measure the horizontal and vertical pose of the mask 7 based on the upward vertical measurement sensor and the upward aligned camera 10; S402: Move the mask stage 6 to the first region position of the substrate and set the mask stage at the substrate measurement height; measure the vertical and horizontal pose of the first region of the substrate based on the downward vertical measurement sensor and the downward aligned camera 8; S403: Calculate the pose deviation of the first region of the mask 7 and the substrate in terms of relative exposure height based on the measurement results in steps S401 and S402; S404: Eliminate the pose deviation calculated in step S403 by moving the substrate using a substrate motion stage; S405: Turn on the illumination system to complete the exposure of the first area of the substrate; Repeat steps S402 to S404 to complete the exposure of the second region of the substrate; … Repeat steps S402 to S404 to complete the exposure of the nth region of the substrate; Exposure is completed for all areas of the substrate to be exposed.
[0043] The exposure motion in this embodiment can be step exposure, one exposure field at a time, or scanning exposure, which is a full-pattern area scan. At the same time, a mask pattern area smaller than the area to be exposed on the substrate can be applied. By moving the mask to different areas above the substrate, the substrate can be exposed in different regions using a similar stepping or scanning method.
[0044] This embodiment can support complete exposure of the substrate when the field of view of the exposure light source is smaller than the area to be exposed on the substrate. Therefore, a more precise exposure light source can be set, and the resolution of near-contact exposure can be improved to below 3µm. The present invention adopts partial stepping or scanning exposure, rather than simultaneous full exposure. Therefore, during the stepping or scanning exposure process, the relative position of the mask and the substrate can be finely adjusted in real time by the mask stage or substrate stage, improving the overlay accuracy to below 1µm.
[0045] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.
Claims
1. A proximity contact exposure apparatus characterized by comprising: include: An illumination system for providing an exposure light source during proximity or contact exposure processes, wherein the field of view of the exposure light source is smaller than the area of the substrate to be exposed, and the illumination field of view during scanning exposure has a smooth transition feature. An alignment system for aligning the mask with corresponding alignment marks on the substrate, the alignment system comprising two sets of alignment sensors whose axes are on the same straight line and whose measurement directions are opposite; A vertical measurement system is used to measure the vertical height and parallelism of the lower surface of a mask relative to the upper surface of a substrate. The vertical measurement system includes an upward vertical measurement sensor and a downward vertical measurement sensor. The alignment system and the vertical measurement system are integrated into a comprehensive measurement system, which is driven by the measurement system's motion stage to perform planar motion, and the stroke covers all graphic areas of the mask. When the mask and the substrate are set at a first relative height, the comprehensive measurement system measures the first relative pose between the mask and the substrate; at a second relative height, it measures the second relative horizontal pose between the mask and the substrate, and calculates the pose deviation between the mask and the substrate at the exposure relative height based on the first relative pose and the second relative horizontal pose. The pose deviation includes the horizontal positional offset and higher-order graphic distortion error between the mask and the substrate, the vertical positional deviation between multiple points of the mask and the substrate, and the vertical surface shape error of the substrate. A mask mounting platform, positioned opposite the lighting system, is used to mount the mask. The substrate stage, which is a substrate motion stage, is arranged opposite to the mask and is used to mount the substrate. It is finely adjusted according to the horizontal positional deviation between the pattern on the substrate and the pattern on the mask within the exposure field of view to compensate for the pose deviation when the substrate is moved. The proximity exposure device uses the illumination system to illuminate the mask on the mask mounting stage, thereby exposing the pattern on the mask to the substrate coated with photoresist on the substrate stage in a proximity or contact manner. The illumination system is mounted on a stepping or scanning motion device, or the mask mounting stage and the substrate stage are mounted as a whole on the stepping or scanning motion device; the stepping or scanning motion device is used to make the mask mounting stage and the substrate stage move in a stepping or scanning plane perpendicular to the exposure light source relative to the illumination system. The exposure process is either scanning exposure or step-by-step exposure.
2. The proximity contact exposure apparatus according to claim 1, wherein The substrate motion stage is used to adjust the pose of the substrate, align the substrate with the mask, and adjust its position in real time during the exposure process.
3. The proximity contact exposure apparatus according to claim 2, wherein The exposure process includes the following steps: S101: The vertical measurement system measures the vertical distance and tilt deviation between the substrate and the mask, and adjusts the vertical distance and tilt deviation to the pre-alignment position by means of the substrate motion stage; S102: The alignment system measures the horizontal positional deviation of the substrate relative to the mask, and adjusts the overall positional deviation between the substrate and the mask by means of the substrate motion stage; S103: The stepping or scanning motion device drives the mask mounting stage and the substrate stage to perform stepping or scanning planar motion relative to the exposure light source. At the same time, the substrate motion stage makes real-time fine adjustments to reduce the horizontal positional deviation between the pattern on the substrate and the pattern on the mask within the exposure field of view, until all areas of the substrate to be exposed are exposed.
4. The proximity contact exposure apparatus according to claim 1, wherein The graphic area of the mask is smaller than the area to be exposed on the substrate; the mask mounting stage is a mask motion stage; the mask motion stage is used to drive the mask to make planar movement perpendicular to the exposure light source.
5. The proximity contact exposure apparatus according to claim 4, wherein The exposure process includes the following steps: S201: The vertical measurement system measures the vertical distance and tilt deviation between the substrate and the mask, and adjusts the vertical distance and tilt deviation to the pre-aligned position by means of the substrate motion stage; S202: The alignment system measures the horizontal positional deviation of the substrate relative to the mask, and reduces the overall positional deviation between the first exposure area of the substrate and the mask by means of the substrate motion stage; S203: The stepping or scanning motion device drives the mask mounting stage and the substrate stage to perform stepping or scanning planar motion relative to the exposure light source. At the same time, the substrate motion stage makes real-time fine adjustments to reduce the horizontal positional deviation between the pattern on the substrate and the pattern on the mask within the exposure field of view, until the first region of the substrate is exposed. S204: Based on the movement of the mask stage and / or the stepping or scanning motion device, align the second exposure area of the substrate with the mask; then repeat steps S201 to S203 to expose the second area of the substrate. ... Based on the movement of the mask stage and / or the stepping or scanning motion device, the nth region of the substrate is aligned with the mask; then, steps S201 to S203 are repeated to expose the nth region of the substrate. Exposure is completed for all areas of the substrate to be exposed.
6. The proximity contact exposure apparatus according to claim 1, wherein Both the vertical measurement system and the alignment system employ a face-to-face measurement method, inserted between the substrate and the mask, to measure the relative pose of the mask and the substrate.
7. The proximity contact exposure apparatus according to claim 6, wherein Both the mask and the substrate are provided with multiple pairs of alignment marks; the alignment system is used to measure multiple sets of alignment marks on the mask and the substrate, and calculates the horizontal positional offset and higher-order graphic distortion error between the mask and the substrate; the vertical measurement system is used to measure the vertical positional deviation between multiple points on the mask and the substrate, and calculates the vertical positional deviation between the mask and the substrate and the vertical surface shape error of the substrate.