Gap detection system, method and method for focal plane correction

Abstract

The disclosure provides a gap detection system for detecting global gap data between a template and a substrate, comprising: a support frame; a template holder comprising a focus detection module for monitoring gap data between the template and the substrate in real time; a workpiece table module comprising a piece supporting table for adjusting the position and attitude of the substrate; an upright surface shape detection module for detecting the substrate to obtain first surface shape data; a folded surface shape detection module capable of switching positions between a detection position and an avoidance position for detecting the template to obtain second surface shape data; and a control system for acquiring position data of the template and the substrate and calibration data of the upright surface shape detection module and the folded surface shape detection module, and for calculating global gap data between the template and the substrate by combining the position data, the calibration data, the first surface shape data and the second surface shape data after acquiring the inclination angle between the template and the substrate.

Description

Technical Field

[0001] This disclosure relates to the field of optical inspection technology, specifically to a gap detection system, method, and focal plane correction method. Background Technology

[0002] When the exposure template and substrate are in contact, micro-contact, or have a small gap, traditional off-axis triangulation detection methods are completely incompatible with small-gap detection optical paths. Traditional white light interferometry gap detection methods can only achieve three-point detection of the focal plane, and these points are far from the exposure pattern area, failing to fully and accurately reflect the focal plane information of the exposure field. While traditional in-situ gap detection methods can detect focal plane information within the pattern area of ​​the template, the space for lattice fiber arrangement is limited, allowing only detection of focal plane information at finite locations. A more significant problem is that this method requires processing detection windows on the template, but the template pattern cannot be designed at the location of the detection window, which severely affects the layout of the template pattern and thus reduces the integration density of the pattern. Summary of the Invention

[0003] (a) Technical problems to be solved

[0004] To address the aforementioned issues, this disclosure provides a gap detection system, method, and focal plane correction method to solve the technical problems of limited detection space, small detection area, and impact on the layout of template graphics in traditional methods.

[0005] (II) Technical Solution

[0006] This disclosure provides a gap detection system for detecting global gap data between a template and a substrate, comprising: a support frame; a template frame including a focus detection module for real-time monitoring of gap data between the template and the substrate; a workpiece stage module including a support stage for adjusting the position and orientation of the substrate; a frontal profile detection module fixed to the upper substrate of the support frame for detecting the substrate and obtaining first profile data; a folded profile detection module, capable of switching between a detection position and an avoidance position, for detecting the template and obtaining second profile data; and a control system for acquiring position data of the template and substrate, as well as calibration data of the frontal profile detection module and the folded profile detection module, and, after acquiring the tilt angle between the template and the substrate, for calculating global gap data between the template and the substrate by combining the position data, calibration data, first profile data, and second profile data.

[0007] Furthermore, the template frame also includes: a support plate, fixed to the upper base plate of the support frame; a template suction cup, fixed to the support plate; the template is adsorbed onto the template suction cup; and the focus detection module is installed on the support plate.

[0008] Furthermore, the workpiece stage module also includes: a coarse stage, mounted on the lower base plate of the support frame; a fine stage, mounted on the coarse stage; the coarse stage and the fine stage are used to adjust the position and orientation of the base plate; and a substrate support stage is mounted on the fine stage.

[0009] Furthermore, the frontal facade shape detection module is one of the following: mechanical phase-shifting laser interferometer, dynamic phase-shifting laser interferometer, Thyman-Green type dynamic phase-shifting interferometer, and short-coherence Fizeau type laser interferometer.

[0010] Furthermore, the folded surface shape detection module includes: a position adjustment mechanism, installed on the side plate of the support frame, used to drive the folded surface shape detection module to switch between the detection position and the avoidance position; a surface shape detection mirror group, a reflector group and a reference mirror group, used to fold the optical path 90° to perform surface shape detection on the template.

[0011] Furthermore, the folded surface shape detection module is either an upright folded surface shape detection module or an inverted folded surface shape detection module; the folded surface shape detection module achieves linear or rotational movement through a position adjustment mechanism to switch between the detection position and the avoidance position.

[0012] Furthermore, the gap detection system also includes: a vibration isolation foundation and an active vibration isolation platform, which, together with the support frame, form the system skeleton to provide a stable detection base and installation frame.

[0013] This disclosure also provides a method for gap detection based on the aforementioned gap detection system, comprising: S1, calibrating the relative positional relationship of the template, substrate, frontal surface shape detection module, and folded surface shape detection module to obtain positional data of the template and substrate; S2, calibrating the frontal surface shape detection module and folded surface shape detection module using a calibration method based on the absolute detection standard for interference surface shapes to obtain calibration data; S3, detecting the substrate using the frontal surface shape detection module to obtain first surface shape data; S4, detecting the template using the folded surface shape detection module to obtain second surface shape data; and S5, switching the folded surface shape detection module to an avoidance position. After the substrate is moved to the global gap detection position, the gap data between the template and the substrate is measured using the focus detection module. Based on the gap data, the template and the substrate are precisely leveled. Then, the global gap data between the template and the substrate is calculated based on the position data, calibration data, first surface shape data, and second surface shape data. Alternatively, the folding surface shape detection module is switched to the avoidance position, and after the substrate is moved to the global gap detection position, the gap data between the template and the substrate is measured using the focus detection module. The tilt angle between the template and the substrate is calculated. Then, the global gap data between the template and the substrate is calculated based on the position data, calibration data, tilt angle, first surface shape data, and second surface shape data.

[0014] Furthermore, the front elevation shape detection module is a small-diameter shape detection module. S3 includes: using the small-diameter shape detection module to perform full-diameter splicing detection on the substrate to obtain the shape data of each splicing part; in the non-overlapping area of ​​the splicing part, using the shape data of the non-overlapping area as the first splicing data; in the overlapping area of ​​the splicing part, selecting the shape data of the splicing part corresponding to the edge away from the splicing part as the second splicing data; merging the first splicing data and the second splicing data to obtain the first shape data.

[0015] This disclosure also provides a method for focal plane correction based on the aforementioned gap detection system, comprising: S1, calibrating the relative positional relationship of the template, substrate, frontal surface shape detection module, and folded surface shape detection module to obtain positional data of the template and substrate; S2, calibrating the frontal surface shape detection module and folded surface shape detection module using the interference surface shape absolute detection standard calibration method to obtain calibration data; S3, detecting the substrate using the frontal surface shape detection module to obtain first surface shape data; S4, detecting the template using the folded surface shape detection module to obtain second surface shape data; S5, switching the folded surface shape detection module to an avoidance position, and after the substrate moves to the global gap detection position, using... The gap data between the template and the substrate is measured using the focus detection module. The template and the substrate are precisely leveled based on the gap data. Then, the global gap data between the template and the substrate is calculated based on the position data, calibration data, first surface shape data, and second surface shape data. Alternatively, the folding surface shape detection module is switched to the avoidance position, and the substrate is moved to the global gap detection position. The gap data between the template and the substrate is measured using the focus detection module, and the tilt angle between the template and the substrate is calculated. Then, the global gap data between the template and the substrate is calculated based on the position data, calibration data, tilt angle, first surface shape data, and second surface shape data. S6, the focal plane is corrected based on the global gap data so that the upper surface of the substrate is located on the target focal plane.

[0016] (III) Beneficial Effects

[0017] The gap detection system, method, and focal plane correction method disclosed herein utilize a frontal face shape detection module to obtain the first face shape data of the substrate and a folded face shape detection module to obtain the second face shape data of the template. By combining the position data of the template and the substrate with the calibration data of the frontal face shape detection module and the folded face shape detection module, the global gap data between the template and the substrate can be obtained. This achieves nanometer-precision detection of the focal plane within the exposure field, avoiding the problem of inaccurate measurement results obtained by using a single measuring point outside the pattern area, and also avoiding the problem of opening holes in the template pattern area affecting the template pattern layout. Attached Figure Description

[0018] Figure 1A schematic diagram of the gap detection system according to an embodiment of the present disclosure is shown.

[0019] Figure 2 This schematically illustrates the structure of the template frame in the gap detection system according to an embodiment of the present disclosure;

[0020] Figure 3 This schematic diagram illustrates the structure of the workpiece stage module in the gap detection system according to an embodiment of the present disclosure;

[0021] Figure 4 The illustration shows a diagram of local area division and data selection when the front elevation shape detection module is a small-diameter shape detection module according to the embodiments of this disclosure, and a diagram of full-diameter substrate splicing detection.

[0022] Figure 5 This schematic diagram illustrates the structure of a folded surface shape detection module in a gap detection system according to an embodiment of the present disclosure;

[0023] Figure 6 A flowchart illustrating a method for gap detection according to a gap detection system in accordance with an embodiment of the present disclosure is shown.

[0024] Explanation of reference numerals in the attached figures:

[0025] 1. Vibration-isolated foundation; 2. Active vibration isolation platform; 3. Support frame; 4. Template frame; 4-1. Support plate; 4-2. Template suction cup; 4-3. Template; 4-4. Detection module; 5. Workpiece stage module; 5-1. Coarse movement stage; 5-2. Fine movement stage; 5-3. Sheet support stage; 5-4. Base plate; 6. Frontal elevation shape detection module; 7A. Frontal folded surface shape detection module; 7B. Inverted folded surface shape detection module; 7-1. Position adjustment mechanism; 7-2. Surface shape detection mirror group; 7-3. Reflector group; 7-4. Reference mirror group; 8. Control system. Detailed Implementation

[0026] To make the objectives, technical solutions, and advantages of this disclosure clearer, the following detailed description is provided in conjunction with specific embodiments and the accompanying drawings.

[0027] The terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit this disclosure. The terms “comprising,” “including,” etc., as used herein indicate the presence of the stated features, steps, operations, and / or components, but do not exclude the presence or addition of one or more other features, steps, operations, or components.

[0028] It should be noted that if the embodiments of this disclosure involve directional indication, the directional indication is only used to explain the relative positional relationship and movement of the components in a specific posture. If the specific posture changes, the directional indication will also change accordingly.

[0029] The use of ordinal numbers such as "first," "second," "third," etc., in the specification and claims to modify the corresponding elements does not in itself imply or represent any ordinal number of the element, nor does it represent the order of one element with another element, or the order of manufacturing methods. The use of these ordinal numbers is only to enable a clearly distinguishable element with a certain name from another element with the same name.

[0030] To address the challenges in detecting the focal plane of an exposure, this disclosure provides a system and method for detecting the gap between substrates and templates. This method utilizes surface shape measurement data of the substrate and template, combined with precise position calibration and overall gap detection and leveling, to achieve the detection of the gap between the substrate and template within the exposure field.

[0031] This disclosure provides a gap detection system for detecting global gap data between template 4-3 and substrate 5-4. Please refer to [link to relevant documentation]. Figures 1-3 The system includes: a support frame 3; a template frame 4, including a focus detection module 4-4, used to monitor the gap data between the template 4-3 and the substrate 5-4 in real time; a workpiece stage module 5, including a support stage 5-3, used to adjust the position and orientation of the substrate 5-4; a frontal profile detection module 6, fixed on the upper substrate of the support frame 3, used to detect the substrate 5-4 and obtain first profile data; a folding profile detection module, which can switch between detection position and avoidance position, used to detect the template 4-3 and obtain second profile data; and a control system 8, used to acquire the position data of the template 4-3 and the substrate 5-4, as well as the calibration data of the frontal profile detection module 6 and the folding profile detection module. After acquiring the tilt angle between the template 4-3 and the substrate 5-4, the system combines the position data, calibration data, first profile data, and second profile data to calculate the global gap data between the template 4-3 and the substrate 5-4.

[0032] After the template 4-3 and substrate 5-4 are mounted, the frontal surface shape detection module 6 is positioned above the substrate 5-4 to obtain the first surface shape data of the substrate 5-4; the folded surface shape detection module is positioned above or below the template 4-3 (i.e., the detection position) to obtain the second surface shape data of the template 4-3. Then, the folded surface shape detection module switches to the avoidance position, and the workpiece stage module 5 carries the substrate 5-4 to the global gap detection position. The focus detection module 4-4 monitors the gap data between the template 4-3 and the substrate 5-4. Combined with the precision position calibration and surface shape data, the global gap data between the template 4-3 and the substrate 5-4 can be obtained. No special processing is required for the template 4-3 and the substrate 5-4. This achieves nanometer-precision detection of the focal plane within the exposure field, avoiding the problem of inaccurate measurement results obtained by using a single measuring point outside the pattern area, and also avoiding the problem of opening holes in the template pattern area affecting the template pattern layout.

[0033] Based on the above embodiments, such as Figure 2 As shown, the template frame 4 also includes: a support plate 4-1, fixed on the upper base plate of the support frame 3; a template suction cup 4-2, fixed on the support plate 4-1; a template 4-3 adsorbed on the template suction cup 4-2; and a focus detection module 4-4 installed on the support plate 4-1.

[0034] The lower surface of template 4-3 is coated with a metal film layer and has a pattern to be exposed. The focus detection module 4-4 is installed on the support plate 4-1. There are at least three sets of focus detection modules 4-4, which are used to monitor the overall gap and tilt between template 4-3 and substrate 5-4 in real time. The focus detection module 4-4 is located outside the pattern area of ​​template 4-3.

[0035] Based on the above embodiments, such as Figure 3 As shown, the workpiece stage module 5 also includes: a coarse stage 5-1, which is mounted on the lower base plate of the support frame 3; a fine stage 5-2, which is mounted on the coarse stage 5-1; the coarse stage 5-1 and the fine stage 5-2 are used to adjust the position and orientation of the base plate 5-4; and a plate support stage 5-3 is mounted on the fine stage 5-2.

[0036] According to the stroke and precision control requirements, the control system 8 moves the coarse stage 5-1 and the fine stage 5-2 to different positions, and at the same time adjusts the attitude of the base plate 5-4, such as the circumferential angle or the pitch angle.

[0037] Based on the above embodiments, the frontal shape detection module 6 is one of a mechanical phase-shifting laser interferometer, a dynamic phase-shifting laser interferometer, a Thyman-Green dynamic phase-shifting interferometer, and a short-coherence Fizeau laser interferometer.

[0038] The frontal profile detection module 6 can be a large-diameter profile detection module to perform a one-time profile detection on the substrate 5-4 to obtain the first profile data; alternatively, it can use a small-diameter profile detection module, which drives the substrate 5-4 to perform step-by-step splicing through the workpiece stage module 5, obtaining the first profile data through multiple profile detections. Laser interferometers have the advantages of a large measurement field of view and high measurement accuracy, and various laser interferometers can be used in the gap detection system and method of this disclosure.

[0039] Based on the above embodiments, such as Figure 5 As shown, the folded surface shape detection module includes: a position adjustment mechanism 7-1, which is installed on the side base plate of the support frame 3 and is used to drive the folded surface shape detection module to switch between the detection position and the avoidance position; a surface shape detection mirror group 7-2, a reflector group 7-3 and a reference mirror group 7-4, which are used to fold the optical path 90° to perform surface shape detection on the template 4-3.

[0040] The folded surface shape detection module folds the optical path of the standard interferometer by 90° for measurement, reducing the complexity of the longitudinal layout of the detection position and facilitating position switching of the folded surface shape detection module. Specifically, the reflector group 7-3 is installed at the rear end of the folded surface shape detection module, and the reference mirror group 7-4 is installed on the reflector group 7-3. The position adjustment mechanism 7-1 can move the folded surface shape detection module to the detection position for surface shape testing of template 4-3. After the test is completed, the position adjustment mechanism 7-1 moves the folded surface shape detection module away from the detection position and switches to an avoidance position. The movement can be linear or rotational.

[0041] Based on the above embodiments, the folded surface shape detection module is either an upright folded surface shape detection module 7A or an inverted folded surface shape detection module 7B; the folded surface shape detection module achieves linear or rotational movement through the position adjustment mechanism 7-1 to switch between the detection position and the avoidance position.

[0042] The position adjustment mechanism 7-1 can move the folded surface shape detection module to switch the position of the upright folded surface shape detection module 7A or the inverted folded surface shape detection module 7B. When the template 4-3 is changed, the position adjustment mechanism 7-1 switches to the detection position, that is, directly above or below the template 4-3, to detect the surface shape of the graphic area of ​​the template 4-3. During exposure, the position adjustment mechanism 7-1 switches to the avoidance position to avoid interference with exposure lighting, detection, and workpiece stage movement. The upright folded surface shape detection module 7A needs to pass through the substrate of the template 4-3 to detect the surface shape of the graphic surface, and it detects the surface shape of the lower surface of the substrate of the template 4-3 (the interface between the film layer and the substrate). To reduce the impact of film thickness on the surface shape detection results, the film thickness deviation should be controlled as small as possible, typically less than 1nm within a diameter of 50mm.

[0043] Based on the above embodiments, the gap detection system also includes: a vibration isolation foundation 1 and an active vibration isolation platform 2, which together with the support frame 3 form the system skeleton to provide a stable detection base and installation frame.

[0044] The vibration isolation foundation 1, the active vibration isolation platform 2, and the support frame 3 are installed in a constant temperature, constant humidity, and clean environment to provide stable testing conditions and component mounting bases and frames for the entire system.

[0045] This disclosure also provides a method for gap detection based on the aforementioned gap detection system, such as... Figure 6 As shown, the process includes: S1, calibrating the relative positions of template 4-3, substrate 5-4, frontal surface shape detection module 6, and folded surface shape detection module to obtain position data of template 4-3 and substrate 5-4; S2, calibrating the frontal surface shape detection module 6 and folded surface shape detection module using the calibration method of the absolute detection standard for interference surface shape to obtain calibration data; S3, using the frontal surface shape detection module 6 to detect substrate 5-4 to obtain first surface shape data; S4, using the folded surface shape detection module to detect template 4-3 to obtain second surface shape data; S5, after switching the folded surface shape detection module to the avoidance position and moving substrate 5-4 to the global gap detection position, using the focus detection module 4-4 to measure the position of template 4-3 relative to substrate 5-4. The gap data between plates 5-4 is used to precisely level template 4-3 and substrate 5-4, making them parallel to each other. Then, the global gap data between template 4-3 and substrate 5-4 is calculated based on position data, calibration data, first surface shape data, and second surface shape data. Alternatively, the folding surface shape detection module can be switched to the avoidance position, and substrate 5-4 can be moved to the global gap detection position. The gap data between template 4-3 and substrate 5-4 can be obtained using focus detection module 4-4, and the tilt angle between template 4-3 and substrate 5-4 can be calculated. Then, the global gap data between template 4-3 and substrate 5-4 can be calculated based on position data, calibration data, tilt angle, first surface shape data, and second surface shape data.

[0046] The gap detection method first obtains the position data of template 4-3 and substrate 5-4, and the calibration data of the frontal face shape detection module 6 and the folded face shape detection module (to eliminate system errors). Then, it detects the first face shape data of substrate 5-4 and the second face shape data of template 4-3. After acquiring the face shape data, the folded face shape detection module switches to an avoidance position, and substrate 5-4 moves to the global gap detection position, i.e., directly below template 4-3. Subsequent calculation of the global gap data includes two schemes. The first scheme uses the gap data measured by the focus detection module 4-4 to precisely level template 4-3 and substrate 5-4, eliminating the tilt angle between them and making template 4-3 and substrate 5-4 parallel to each other. The reason for the flatness is that there is a tilt angle between the template 4-3 and the substrate 5-4. The gap data calculated based on the first surface shape data and the second surface shape data at a certain position is not the actual gap data. Therefore, it is necessary to make the template 4-3 and the substrate 5-4 parallel to each other, and then calculate the global gap data between the template 4-3 and the substrate 5-4 based on the position data, calibration data, first surface shape data and second surface shape data. The second solution is to first use the gap data measured by the focus detection module 4-4 to calculate the tilt angle, and then calculate the global gap data between the template 4-3 and the substrate 5-4 based on the position data, calibration data, tilt angle, first surface shape data and second surface shape data (the global gap data can be obtained by eliminating the tilt angle during surface shape calculation).

[0047] This disclosure transforms the measurement of the distance between the substrate 5-4 and the template 4-3 into measuring the surface shapes of the substrate 5-4 and the template 4-3 separately at two spatially separated locations. After matching their horizontal positions one by one, the distance between the two plates is obtained based on the surface shape data of the two plates. This solves the problem of the limited installation position of conventional gap detection devices, and also solves the problem of the template pattern area being affected by the need to perforate the template pattern surface.

[0048] Based on the above embodiments, the frontal facade shape detection module 6 is a small-diameter facade shape detection module. S3 includes: using the small-diameter facade shape detection module to perform full-diameter splicing detection on the substrate 5-4 to obtain the facade shape data of each splicing part; in the non-overlapping area of ​​the splicing part, using the facade shape data of the non-overlapping area as the first splicing data; in the overlapping area of ​​the splicing part, selecting the facade shape data of the splicing part corresponding to the edge away from the splicing part as the second splicing data; merging the first splicing data and the second splicing data to obtain the first facade shape data.

[0049] When the front facade shape detection module 6 is a small-diameter facade shape detection module, such as Figure 4As shown, for example, substrate 5-4 is an 8-inch substrate. A full-aperture splicing inspection is completed through 9 fields (3×3) to obtain the full-aperture surface topography undulation data. To avoid the splicing seam treatment affecting the accuracy of the data, the local surface topography data within the 9 fields were optimized. As long as it's not exactly at the splicing seam, any field's inspection data can be selected. This ensures that the original data from the single-field test of the frontal surface topography inspection module 6 is used, while also ensuring that the local area covers the entire 8-inch substrate 5-4.

[0050] like Figure 4 As shown in the left-middle section, in the 9-field partition, those without overlap with other regions are directly used for surface shape stitching; for those with overlap with other fields, after aligning the overlapping parts (usually using the surface morphology of the central part of the overlapping region as a feature to align the surface shape data between different fields), surface shape data from the overlapping fields far from the edges of each field are extracted for full-aperture surface shape stitching. For example, in overlapping region 10, the left side is close to the edge of field 2, and the right side is close to the edge of field 1. Then, after aligning field 1 and field 2 based on the surface morphology features of the central part of overlapping region 10, at different points in the two surface shape data, the surface shape data on the left side of overlapping region 10 preferentially uses the original surface shape detection data from field 1, and the surface shape data on the right side of overlapping region 10 preferentially uses the original surface shape detection data from field 2. The surface shape data of overlapping region 11 (three fields) and overlapping region 12 (four fields) are obtained using the same method. The distance of a point in the overlapping region from the edge of a field can be determined based on the distance between that point and the center of a specific field. For example, the distance between a point in the overlapping region 10 and the center of the first field is L1, and the distance between the point and the center of the second field is L2. If L1 is less than L2, then if the surface data of that point in the two fields are different, the original surface detection data in field 1 is selected as the data required for splicing. Figure 4 The middle right section shows a schematic diagram of how the frontal facade shape detection module 6, when it is a small-diameter facade shape detection module, completes the splicing detection of the full-diameter substrate through 3×3 fields (9 fields in total).

[0051] This disclosure also provides a method for focal plane correction based on the aforementioned gap detection system, comprising: S1, calibrating the relative positional relationship of template 4-3, substrate 5-4, frontal surface shape detection module 6, and folded surface shape detection module to obtain positional data of template 4-3 and substrate 5-4; S2, calibrating the frontal surface shape detection module 6 and folded surface shape detection module using the interference surface shape absolute detection standard calibration method to obtain calibration data; S3, using the frontal surface shape detection module 6 to detect substrate 5-4 to obtain first surface shape data; S4, using the folded surface shape detection module to detect template 4-3 to obtain second surface shape data; S5, after switching the folded surface shape detection module to an avoidance position and moving substrate 5-4 to a global gap detection position, using the focus detection module 4-4 to monitor the relationship between template 4-3 and substrate 5-4. The gap data is used to precisely level the template 4-3 and the substrate 5-4 so that the template 4-3 and the substrate 5-4 are parallel to each other; then, the global gap data between the template 4-3 and the substrate 5-4 is calculated based on the position data, calibration data, first surface data and second surface data; or, after the folding surface detection module is switched to the avoidance position and the substrate 5-4 is moved to the global gap detection position, the gap data between the template 4-3 and the substrate 5-4 is obtained using the focus detection module 4-4, and the tilt angle between the template 4-3 and the substrate 5-4 is calculated; then, the global gap data between the template 4-3 and the substrate 5-4 is calculated based on the position data, calibration data, tilt angle, first surface data and second surface data; S6, the focus surface is corrected based on the global gap data so that the upper surface of the substrate 5-4 is located on the target focus surface.

[0052] Furthermore, the global gap data obtained in S1 to S5 can be used for focal plane correction to ensure that the upper surface of substrate 5-4 is located on the target focal plane, thereby achieving optimal exposure. Steps S1 to S5 are the same as the aforementioned gap detection method and will not be repeated here.

[0053] The present disclosure will be further described below through specific embodiments. The gap detection system, method, and focal plane correction method described above will be specifically illustrated in the following embodiments. However, the following embodiments are merely illustrative of the present disclosure, and the scope of the present disclosure is not limited thereto.

[0054] like Figure 1As shown, the overall structure of this embodiment includes a vibration isolation foundation 1, an active vibration isolation platform 2, a support frame 3, a template frame 4, a workpiece table module 5, a control system 8, a frontal elevation shape detection module 6, and a frontal folded surface shape detection module 7A (or an inverted folded surface shape detection module 7B). The gap detection system is composed of the template frame 4, the workpiece table module 5, the control system 8, the frontal elevation shape detection module 6, and the frontal folded surface shape detection module 7A (or an inverted folded surface shape detection module 7B). The template frame 4 holds a template 4-3, and the workpiece table module 5 supports a base plate 5-4.

[0055] like Figure 2 , Figure 3 As shown, the vibration isolation foundation 1, active vibration isolation platform 2, and support frame 3 are integrated and assembled to form the system skeleton. The template frame 4 includes a support plate 4-1, a template suction cup 4-2, and a focus detection module 4-4. Three identical focus detection modules 4-4 are installed on the support plate 4-1 to monitor the overall gap and tilt between the template 4-3 and the substrate 5-4 in real time. The workpiece stage module 5 includes a coarse motion stage 5-1, a fine motion stage 5-2, and a support stage 5-3. The coarse motion stage 5-1 and the fine motion stage 5-2 are used to adjust the position and orientation of the substrate 5-4. The front elevation shape detection module 6 can be a large-diameter shape detection module to perform a one-time shape detection of the substrate 5-4, or it can use a small-diameter shape detection module to drive the substrate 5-4 to perform step-by-step splicing through the workpiece stage module 5. Through multiple shape detections, the surface morphology detection is completed, and the first shape data is obtained. The folded surface shape detection module includes a position adjustment mechanism 7-1, a surface shape detection mirror group 7-2, a reflector group 7-3, and a reference mirror group 7-4, used to fold the optical path 90° to perform surface shape detection on the template 4-3. The control system 8 acquires the position data of the template 4-3 and the substrate 5-4, as well as the calibration data of the frontal surface shape detection module 6 and the folded surface shape detection module. After acquiring the tilt angle between the template 4-3 and the substrate 5-4, it combines the position data, calibration data, first surface shape data, and second surface shape data to calculate the global gap data between the template 4-3 and the substrate 5-4.

[0056] Based on the above gap detection system, the steps of the gap detection method and focal plane correction method are as follows:

[0057] Step 1: The template 4-3 and the substrate 5-4 are loaded onto the substrate using the transfer system. In order to obtain the gap between the two based on the surface shape data of the template 4-3 and the substrate 5-4, it is necessary to strictly control the loading error of the two.

[0058] Step 2: Using the graphic marks on the workpiece stage module 5, template 4-3, and substrate 5-4, calibrate the relative positional relationships in the XY and TZ directions between the frontal face shape detection module 6, the frontal folded face shape detection module 7A or the inverted folded face shape detection module 7B, template 4-3, and substrate 5-4 to ensure that the positions of template 4-3 and substrate 5-4 correspond one-to-one during detection and exposure. The control system 8 records the position data (x, y) of template 4-3 and substrate 5-4; this is equivalent to step S1 above.

[0059] Step 3: Using the absolute interference surface shape detection standard calibration procedure, calibrate the reference mirror group 7-4 of the frontal surface shape detection module 6, the frontal folded surface shape detection module 7A, or the inverted folded surface shape detection module 7B. The control system 8 records the calibration data S(x, y), where S(x, y) is the calibration data S1(x, y) of the frontal surface shape detection module 6, the calibration data S2(x, y) of the frontal folded surface shape detection module 7A, or the calibration data S3(x, y) of the inverted folded surface shape detection module 7B; equivalent to step S2 above.

[0060] Step 4: The workpiece stage module 5 moves to the front elevation shape detection module 6 to complete the global surface shape detection of the substrate 5-4, and the control system 8 records the first surface shape data W(x, y); equivalent to step S3 above.

[0061] Step 5: The position adjustment mechanism 7-1 switches to the detection position to detect the surface shape of the working area of ​​the template 4-3, and the control system 8 records the second surface shape data M(x, y); equivalent to step S4 above.

[0062] Step 6: The position adjustment mechanism 7-1 switches to the avoidance position, the workpiece stage module 5 moves to the global gap detection position, and the control system 8, based on the gap data of the three outer points detected by the coking module 4-4, feeds back to control the workpiece stage module 5 to perform precise leveling and gap control on the template 4-3 and the base plate 5-4, so that the template 4-3 and the base plate 5-4 are parallel to each other.

[0063] Step 7: The control system 8 automatically matches the global gap data F(x,y) at any position in the current exposure area based on the position data (x,y), calibration data S(x,y), the first surface data W(x,y) obtained by the frontal surface detection module 6, and the second surface data M(x,y) obtained by the folded surface detection module. F(x,y) = M(x,y) - W(x,y) - S(x,y); which is equivalent to step S5 above.

[0064] Step 8: The control system 8 determines whether it is necessary to use light field adjustment or focal plane active control mechanism to correct the focal plane in order to achieve the best exposure effect based on the global gap data F(x, y); this is equivalent to step S6 above.

[0065] This disclosure further verifies the feasibility of the gap detection method and the focal plane correction method. As shown in Table 1, the focal plane detection results under different gaps are given. When the average gaps are 102.7 nm, 94.3 nm, 84.5 nm, and 77.3 nm, the corresponding deviations of the focal plane detection PV and RMS values ​​are less than 0.4 nm, indicating that the method proposed in this disclosure has good focal plane detection consistency and focal plane correction reliability.

[0066] Table 1

[0067] Test serial number Average gap value / nm PV value / nm RMS value / nm 1 102.7 24.31 3.66 2 94.3 24.01 3.79 3 84.5 24.36 3.93 4 77.3 24.67 3.94

[0068] The specific embodiments described above further illustrate the purpose, technical solutions, and beneficial effects of this disclosure. It should be understood that the above descriptions are merely specific embodiments of this disclosure and are not intended to limit this disclosure. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this disclosure should be included within the protection scope of this disclosure.

Claims

1. A gap detection system for detecting global gap data between a template (4-3) and a substrate (5-4), characterized in that, include: Supporting framework (3); The template frame (4) includes a focus detection module (4-4) for real-time monitoring of the gap data between the template (4-3) and the substrate (5-4); the template frame (4) also includes: a support plate (4-1) fixed on the upper substrate of the support frame (3); a template suction cup (4-2) fixed on the support plate (4-1); the template (4-3) is adsorbed on the template suction cup (4-2), and the focus detection module (4-4) is installed on the support plate (4-1); The workpiece stage module (5) includes a support stage (5-3) for adjusting the position and orientation of the substrate (5-4); the workpiece stage module (5) also includes: a coarse adjustment stage (5-1) mounted on the lower substrate of the support frame (3); and a fine adjustment stage (5-2) mounted on the coarse adjustment stage (5-1); the coarse adjustment stage (5-1) and the fine adjustment stage (5-2) are used to adjust the position and orientation of the substrate (5-4); the support stage (5-3) is mounted on the fine adjustment stage (5-2); The front elevation shape detection module (6) is fixed on the upper base plate of the support frame (3) and is used to detect the base plate (5-4) to obtain the first surface shape data; The folded surface shape detection module can switch between a detection position and an avoidance position to detect the template (4-3) and obtain second surface shape data. The folded surface shape detection module includes: a position adjustment mechanism (7-1), which is installed on the side plate of the support frame (3) and is used to drive the folded surface shape detection module to switch between the detection position and the avoidance position; a surface shape detection mirror group (7-2), a reflector group (7-3), and a reference mirror group (7-4), which are used to fold the optical path by 90° to detect the surface shape of the template (4-3). The control system (8) is used to acquire the position data of the template (4-3) and the substrate (5-4) as well as the calibration data of the front elevation shape detection module (6) and the folded surface shape detection module. After acquiring the tilt angle between the template (4-3) and the substrate (5-4), it is used to calculate the global gap data between the template (4-3) and the substrate (5-4) by combining the position data, the calibration data, the first surface shape data and the second surface shape data.

2. The gap detection system according to claim 1, characterized in that, The frontal shape detection module (6) is one of the following: mechanical phase-shifting laser interferometer, dynamic phase-shifting laser interferometer, Thyman-Green type dynamic phase-shifting interferometer, and short-coherence Fizeau type laser interferometer.

3. The gap detection system according to claim 1, characterized in that, The folded surface shape detection module is either an upright folded surface shape detection module (7A) or an inverted folded surface shape detection module (7B). The folded surface shape detection module achieves linear or rotational movement through the position adjustment mechanism (7-1) to switch between the detection position and the avoidance position.

4. The gap detection system according to claim 1, characterized in that, The gap detection system also includes: The vibration isolation foundation (1) and the active vibration isolation platform (2), together with the support frame (3), form the system skeleton, which is used to provide a stable detection base and installation frame.

5. A method for gap detection using the gap detection system according to any one of claims 1 to 4, characterized in that, include: S1, calibrate the relative positional relationship of the template (4-3), the substrate (5-4), the front elevation shape detection module (6), and the folded surface shape detection module to obtain the positional data of the template (4-3) and the substrate (5-4); S2, using the calibration method of the absolute detection standard for interference surface shape, the frontal surface shape detection module (6) and the folded surface shape detection module are calibrated to obtain calibration data; S3, the front elevation shape detection module (6) is used to detect the substrate (5-4) to obtain the first surface shape data; S4, the template (4-3) is detected using the folded surface shape detection module to obtain the second surface shape data; S5, after the folded surface shape detection module switches to the avoidance position and the substrate (5-4) moves to the detection position, the gap data between the template (4-3) and the substrate (5-4) is measured using the focus detection module (4-4). Based on the gap data, the template (4-3) and the substrate (5-4) are precisely leveled to make them parallel. Then, based on the position data, the calibration data, the first surface shape data, and the second surface shape data, the global gap data between the template (4-3) and the substrate (5-4) is calculated. After the folding surface shape detection module is switched to the avoidance position and the substrate (5-4) is moved to the global gap detection position, the gap data between the template (4-3) and the substrate (5-4) is measured by the focus detection module (4-4), and the tilt angle between the template (4-3) and the substrate (5-4) is calculated. Then, the global gap data between the template (4-3) and the substrate (5-4) is calculated based on the position data, the calibration data, the tilt angle, the first surface shape data and the second surface shape data.

6. The method for gap detection according to claim 5, characterized in that, The front elevation shape detection module (6) is a small-diameter surface shape detection module, and S3 includes: The small-diameter surface shape detection module is used to perform full-diameter splicing detection on the substrate (5-4) to obtain the surface shape data of each splicing part; In the non-overlapping area of ​​the splicing portion, the surface shape data of the non-overlapping area is used as the first splicing data; in the overlapping area of ​​the splicing portion, the surface shape data of the splicing portion corresponding to the edge away from the splicing portion is selected as the second splicing data. The first spliced ​​data and the second spliced ​​data are merged to obtain the first surface data.

7. A method for focal plane correction using a gap detection system according to any one of claims 1 to 4, characterized in that, include: S1, calibrate the relative positional relationship of the template (4-3), the substrate (5-4), the front elevation shape detection module (6), and the folded surface shape detection module to obtain the positional data of the template (4-3) and the substrate (5-4); S2, using the absolute detection standard calibration method for interference surface shape, the front elevation shape detection module (6) and the folded surface shape detection module are calibrated to obtain calibration data; S3, the front elevation shape detection module (6) is used to detect the substrate (5-4) to obtain the first surface shape data; S4, the template (4-3) is detected using the folded surface shape detection module to obtain the second surface shape data; S5, after the folded surface shape detection module is switched to the avoidance position and the substrate (5-4) is moved to the global gap detection position, the gap data between the template (4-3) and the substrate (5-4) is measured using the focus detection module (4-4). Based on the gap data, the template (4-3) and the substrate (5-4) are precisely leveled to make the template (4-3) and the substrate (5-4) parallel to each other. Then, based on the position data, the calibration data, the first surface shape data, and the second surface shape data, the global gap data between the template (4-3) and the substrate (5-4) is calculated; or After the folding surface shape detection module is switched to the avoidance position and the substrate (5-4) is moved to the global gap detection position, the gap data between the template (4-3) and the substrate (5-4) is measured by the focus detection module (4-4), and the tilt angle between the template (4-3) and the substrate (5-4) is calculated; then, based on the position data, the calibration data, the tilt angle, the first surface shape data and the second surface shape data, the global gap data between the template (4-3) and the substrate (5-4) is calculated. S6, perform focal plane correction based on the global gap data so that the upper surface of the substrate (5-4) is located on the target focal plane.

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