An exposure detection system, a holographic exposure system and methods of using the same

Abstract

This disclosure discloses an exposure detection system, a holographic exposure system, and a method for using the same, comprising: a beam combining module for combining an illumination beam and a visible indicator beam, and directing the combined beam toward a mask to be tested; a self-collimation module for receiving the combined beam reflected back from the mask and detecting the perpendicularity deviation between the mask and the combined beam; an illumination adjustment module for aligning the mask perpendicular to the combined beam using an attitude adjustment component; and an alignment module for detecting the horizontal relative position of the center of the mask and the visible indicator beam, and using the attitude adjustment component to align the center of the mask with the visible indicator beam. In this invention, a visible indicator beam is added to the exposure detection system, and the illumination beam and the visible indicator beam are coaxially aligned by the beam combining module. Finally, the illumination adjustment module controls the illumination beam to be perpendicularly incident on the mask, thereby enabling the detection of the illumination beam in the holographic exposure system by detecting the visible indicator beam.

Description

Technical Field

[0001] This disclosure relates to the field of holographic lithography technology, and more specifically, to an exposure detection system for adjusting the orientation of a photomask, an exposure detection system for detecting the state of an illumination beam, an exposure detection control system for optimizing the wavefront of the illumination beam, and a holographic exposure system and its usage method. Background Technology

[0002] Laser holographic lithography is a promising lithography technology. Its basic principle is diffraction imaging. A beam of light illuminates a holographic mask, causing diffraction on microstructures arranged in a certain pattern. These diffracted lights are eventually superimposed on a silicon wafer to obtain the desired pattern. In the field of laser holographic lithography, as the feature size requirements for IC chips become smaller and smaller, the performance requirements for lithography machines become higher and higher, and the requirements for the quality inspection of lithographic patterns also become higher and higher.

[0003] To ensure the quality of the photolithographic pattern, the beam in a holographic exposure system must remain stable in terms of power and directionality. Otherwise, prolonged exposure across multiple regions and over long distances will lead to a decrease in the quality and uniformity of the holographic mask pattern, making efficient pattern projection impossible. The target pattern linewidth (CD) is a key indicator of exposure quality; comparing the measured linewidth with the design value characterizes the performance of the exposure system. Therefore, establishing a sophisticated exposure detection and control system to detect the incident light and control the illumination beam is crucial to fulfilling the exposure function of the mask. Summary of the Invention

[0004] The main objective of this disclosure is to provide an exposure detection system for adjusting the orientation of a mask, an exposure detection system for detecting the state of an illumination beam, an exposure detection control system for optimizing the wavefront of the illumination beam, and a holographic exposure system and its usage method, in order to solve the problem of lack of detection of the illumination beam in the related art.

[0005] Additional aspects and advantages of this disclosure will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of this disclosure.

[0006] According to a first aspect of this disclosure, an exposure detection system for adjusting the orientation of a holographic mask exposure system is provided. The holographic mask exposure system includes a mask and an illumination source; the illumination source emits an illumination beam for exposure. The exposure detection system includes: Indicator light source, used to emit a visible indicator beam; A beam combiner module is configured to receive an illumination beam and a visible indicator beam, combine the illumination beam and the visible indicator beam, and direct the combined beam toward the mask to be tested. The self-collimation module is configured to receive the beam of the combined beam reflected back from the mask and detect the perpendicularity deviation between the mask and the beam of the combined beam by analyzing the position of the reflected spot of the visible indicator beam. The illumination adjustment module includes an alignment module and an attitude adjustment component; the attitude adjustment component is configured to adjust the angle of the mask so that the mask is perpendicular to the beam combining beam; the alignment module is configured to detect the horizontal relative position of the center of the mask and the visible indicator beam; and the attitude adjustment component is configured to adjust the horizontal position of the mask so that the center of the mask coincides with the visible indicator beam.

[0007] In some embodiments of this disclosure, the beam combining module includes: a first beam splitter configured to transmit an illumination beam, reflect a visible indicator beam, and reflect the visible indicator beam into the same optical path as the illumination beam to form a combined beam.

[0008] In some embodiments of this disclosure, the beam combining module further includes: a reflector group; the reflector group is used to reflect the visible indicator beam emitted by the indicator light source to the first beam splitter.

[0009] The specific optical path routing in the aforementioned beam combining module is as follows: The visible indicator beam beam combining path is as follows: after the visible indicator beam emitted by the indicator light source is reflected by the reflector group, the visible indicator beam enters the first beam splitter and forms a beam combining with the illumination beam.

[0010] The beam combining path of the illumination beam is as follows: when the transmitted light is guided to the deformable mirror, the polarization direction of the quarter-wave plate is rotated by 45 degrees so that the transmitted light is incident on the deformable mirror; after the beam passes through the deformable mirror, when the beam is guided to the first beam splitter, the polarization direction of the quarter-wave plate continues to rotate by 45 degrees, and the polarization direction of the incident light on the quarter-wave plate is 90 degrees; at this time, the beam is incident on the first beam splitter to achieve beam combining of the illumination beam and the visible indicator beam.

[0011] In some embodiments of this disclosure, the autocollimation module includes: a second beam splitter and an autocollimation camera. The second beam splitter is disposed in the optical path of the visible indicator beam and is used to reflect the visible indicator beam emitted by the indicator light source to the beam combining module for beam combining. The second beam splitter is also used to transmit the visible indicator beam reflected back from the surface of the mask to be tested to the autocollimation camera. An autocollimating camera is used to receive the visible indicator beam reflected back from the mask surface and obtain its spot position, converting the angular deviation into a position deviation signal.

[0012] During the calibration process of the above-mentioned autocollimation module, the specific optical path is as follows: the visible indicator beam provided by the indicator light source is reflected by the second beam splitter and then returns through the plane mirror to be incident on the autocollimation camera; the autocollimation camera can be driven to adjust its position so that the visible indicator beam hits the center position of the autocollimation camera, thereby completing the calibration of the autocollimation module.

[0013] In some embodiments of this disclosure, the autocollimation module further includes: a plane mirror and at least two first positioning holes spaced apart along the optical axis; At least two first positioning holes are used to allow the visible indicator beam to pass through in order to calibrate the position of the visible indicator beam and ensure that the visible indicator beam is collimated; The autocollimation module has a calibration stage, in which the plane mirror is placed at the measurement position of the autocollimation module and the plane mirror has a known normal direction; The plane mirror is used to reflect the visible indicator beam reflected by the second beam splitter back along the original incident light path; after the visible indicator beam passes through the first positioning hole to calibrate the position, it passes through the second beam splitter and is then incident on the autocollimating camera. During the calibration phase, the position of the autocollimating camera is adjusted so that the spot of the visible indicator beam hits the center of the autocollimating camera, and the deviation is controlled within the preset pixel value. At this time, the position of the spot is calibrated as the zero position of angle measurement.

[0014] In some embodiments of this disclosure, the self-collimation module further includes an optical trap that receives transmitted light after it has been split by the second beam splitter, the transmitted light being absorbed as stray light incident on the optical trap.

[0015] Specifically, the aforementioned optical trap is used to ensure that the incident light beam incident on the optical trap cannot be reflected. During the calibration process, the specific optical path of the self-collimating module with the optical trap is as follows: the visible indicator beam is incident on the second beam-splitting prism, achieving beam splitting; the transmitted light after beam splitting is incident on the optical trap as stray light and is absorbed; the reflected light after beam splitting passes through two spaced first positioning holes, the aperture of which matches the diameter of the incident light to ensure beam collimation. The reflected light through the first positioning hole returns along the same path via the plane mirror and is incident on the autocollimating camera. The center position of the autocollimating camera is adjusted accordingly to align the visible indicator beam with the center position of the autocollimating camera.

[0016] In some embodiments of this disclosure, the light trap is a serrated conical structure coated with black matte paint.

[0017] In some embodiments of this disclosure, the second beam splitter is a semi-transparent and semi-reflective prism that does not require polarization of the incident light, so as to achieve a 50:50 beam splitting ratio. The prism material of the second beam splitter is fused silica, which is formed by curing two right-angle prisms through a photopolymerization process.

[0018] In some embodiments of this disclosure, the plane mirror has a silver coating and a protective film.

[0019] In some embodiments of this disclosure, the verticality detection calculation formula of the self-collimation module is as follows: , Where θ is the angle between the mask and the incident light, σ is the pixel size of the autocollimating camera, n is the number of pixels that the centroid of the incident light deviates from the center of the autocollimating camera, and L is the distance from the autocollimating module to the mask.

[0020] In some embodiments of this disclosure, the autocollimating camera is a large-area camera; the center position of the autocollimating camera is adjusted by control programming software, and the autocollimating camera is driven to move along the horizontal and vertical directions to change its center position in order to control the deviation between the visible indicator beam and the center of the autocollimating camera.

[0021] In some embodiments of this disclosure, the camera target size of the autocollimating camera is greater than or equal to one inch. Preferably, the camera target size of the autocollimating camera is 4 / 3 inch to ensure that the autocollimating camera receives the incident light. The deviation between the visible indicator beam and the center of the autocollimating camera is controlled within one pixel.

[0022] In some embodiments of this disclosure, the beam combining module further includes: a reflector and at least two second positioning holes spaced apart along the optical axis; the edges of the second positioning holes are provided with fluorescent material, which can emit visible light when illuminated by an illumination beam; At least two second positioning holes are provided for the illumination beam and the visible indicator beam to pass through, so as to calibrate the position of the illumination beam and the visible indicator beam and ensure that the illumination beam and the visible indicator beam are coaxial.

[0023] The optical path direction during beam combining is as follows: the illumination beam is incident on the first beam splitter and transmitted, the visible indicator beam emitted by the indicator light source is incident on the first beam splitter and reflected, and the illumination beam and the visible indicator beam merge at the first beam splitter to form a combined beam. After being reflected by a mirror, the combined beam passes through at least two second positioning holes in sequence. By adjusting the illumination beam and the visible indicator beam so that both can pass through the center of at least two second positioning holes, it is determined that the visible indicator beam and the illumination beam are coaxial.

[0024] Furthermore, after the beam is combined and reflected by the mirrors, it needs to be adjusted to ensure that the illumination beam and the visible indicator beam are coaxial. Specifically, the adjustment steps are as follows: adjust the position of the second positioning holes so that the illumination beam can pass through both holes; and adjust the mirror assembly so that the visible indicator beam can also pass through both holes, thus completing the beam combination. After beam combination, the visible indicator beam and the illumination beam are coaxial. This beam combination module solves the adjustment problem caused by the invisibility of the illumination beam, and also allows the visible indicator beam to reflect the attitude of the illumination beam. This facilitates the control of the attitude between the illumination beam and the mask.

[0025] In some embodiments of this disclosure, the number of the second positioning holes can be two or more, each second positioning hole has the same diameter, and the preset distance between adjacent second positioning holes is 1m ± 0.2m.

[0026] In some embodiments of this disclosure, the attitude adjustment component includes: an angle adjustment structure for adjusting the tilt angle of the mask, and a position adjustment structure for adjusting the displacement position of the mask.

[0027] In the adjustment of the angle between the mask and the incident light, the specific optical path is as follows: the visible indicator beam passes through the first beam splitter and the alignment module before being incident on the mask assembly. The mask assembly includes a mask and an attitude adjustment component. The visible indicator beam incident on the mask assembly returns to the autocollimation module via its original path. The angle adjustment structure of the attitude adjustment component then adjusts the tilt angle of the mask, aligning the visible indicator beam with the center of the autocollimation camera, thus completing the adjustment of the angle between the mask and the incident light.

[0028] Furthermore, in this embodiment, the relative position of the center of the mask and the visible indicator beam is observed by the alignment module, and the horizontal position of the mask is adjusted by the position adjustment structure of the attitude adjustment component, so that the center position of the mask coincides with the visible indicator beam. Because the visible indicator beam and the illumination beam are coaxial, the illumination beam and the center position of the mask are completely coincident.

[0029] In some embodiments of this disclosure, the attitude adjustment component further includes: a capacitive sensor disposed on the mask, the capacitive sensor being used to measure the distance between the mask and the silicon wafer in real time to detect the positional state between the mask and the silicon wafer.

[0030] In some embodiments of this disclosure, the first beam splitter is a non-polarization-sensitive beam splitter and combiner prism, formed by bonding two right-angle prisms together using a photopolymer adhesive process. The material of the first beam splitter prism is ultraviolet fused silica, and the coated surface is designed with a transmittance-to-reflection ratio of 99:1 corresponding to the illumination beam, indicating that the reflectivity of the indicator beam on this coated surface is ≥50%. In other embodiments of this disclosure, the aforementioned attitude adjustment component can also perform coarse and fine adjustments on the mask.

[0031] According to a second aspect of this disclosure, this disclosure provides an exposure detection system for detecting the state of an illumination beam, comprising: an exposure detection system for adjusting the orientation of a mask; and a monitoring module.

[0032] A monitoring module is used to detect the status of the illumination beam; the monitoring module includes a power meter and / or a position monitoring camera. The power meter receives the illumination beam to detect its power. In some embodiments of this disclosure, the power meter's beam focus is located outside the detector target surface, thereby avoiding excessive beam focus concentration that could affect the power meter's power measurement accuracy. A position monitoring camera receives the illumination beam to detect its beam directionality.

[0033] In some embodiments of this disclosure, the monitoring module further includes: a half-wave plate and a polarizing beam splitter, as well as a semi-transparent and semi-reflective beam splitter and a focusing lens; The half-wave plate is used to control the polarization direction of the illumination beam; when the monitoring module detects the status of the illumination beam, the illumination beam, whose polarization direction has been changed by the half-wave plate, illuminates the polarization beam splitter. A polarizing beam splitter works in conjunction with a half-wave plate. The polarizing beam splitter is used to split the illumination beam into transmitted light and reflected light. The transmitted light continues to be transmitted as the illumination beam, while the reflected light is reflected into the monitoring optical path of the monitoring module. A semi-transparent, semi-reflective beam splitter is used to receive the illumination beam reflected by a polarizing beam splitter and to split the illumination beam. A focusing lens is positioned in the light path of the power meter to receive the illumination beam split by the semi-transparent and semi-reflective beam splitter and converge the illumination beam to the power meter; and / or, a focusing lens is positioned in the light path of the position monitoring camera to receive the illumination beam split by the semi-transparent and semi-reflective beam splitter and converge the illumination beam to the position monitoring camera.

[0034] During power and beam directivity monitoring, the specific optical path is as follows: First, the angle of the half-wave plate is adjusted to control the polarization direction of the illumination beam. After the illumination beam changes its polarization direction by passing through the half-wave plate, it illuminates the polarizing beam splitter. A portion of the controlled beam is reflected by the polarizing beam splitter, and the reflected beam enters the monitoring optical path of the monitoring module. After being split by a semi-transparent, semi-reflective beam splitter, the beam passes through a focusing lens and enters the power meter and the position monitoring camera respectively, thereby realizing the monitoring of power and beam directivity.

[0035] According to a third aspect of this disclosure, this disclosure provides an exposure detection control system for optimizing the wavefront of an illumination beam, comprising: an exposure detection system for adjusting the orientation of a mask; and an adaptive module.

[0036] The adaptive module is used to modulate the beam incident on the mask to improve the quality of the illumination beam incident on the mask; the adaptive module includes: a wavefront sensor and a deformable mirror; A wavefront sensor is used to detect the wavefront data of the illumination beam and send the wavefront data to a deformable mirror; the deformable mirror is used to receive the wavefront data and modulate the illumination beam to optimize the wavefront of the illumination beam entering the mask.

[0037] In some embodiments of this disclosure, the adaptive module further includes: a half-wave plate, a polarizing beam splitter, a quarter-wave plate, and a first beam splitter; The half-wave plate is used to control the polarization direction of the illumination beam; when the adaptive module performs wavefront optimization on the illumination beam, the illumination beam with its polarization direction changed by the half-wave plate illuminates the polarization beam splitter. A polarizing beam splitter is used in conjunction with a half-wave plate. The polarizing beam splitter is used to split the illumination beam into transmitted light and reflected light. The transmitted light continues to be transmitted as the illumination beam to the quarter-wave plate for wavefront optimization. A quarter-wave plate is used to rotate the polarization direction of the transmitted light, so that the transmitted light, which serves as the illumination beam, is incident on the deformable mirror; The deformable mirror is used to reflect the illumination beam that has passed through the quarter-wave plate. The reflected illumination beam passes through the quarter-wave plate again to change its polarization direction before entering the first beam splitter. The first beam splitter is used to split the illumination beam reflected by the deformable mirror. The illumination beam is transmitted through the first beam splitter to the mask for exposure illumination. The illumination beam is reflected by the first beam splitter to the wavefront sensor to detect wavefront data.

[0038] In optimizing the illumination beam entering the mask, the specific optical path is as follows: the illumination beam emitted by the illumination source passes sequentially through a polarizing beam splitter and a quarter-wave plate before incident on the deformable mirror. The polarizing beam splitter works in conjunction with the quarter-wave plate, splitting the illumination beam into transmitted and reflected light. The transmitted light continues to propagate as the illumination beam to the quarter-wave plate. The quarter-wave plate rotates the polarization direction of the transmitted light by 45°, directing the transmitted light, now the illumination beam, to the deformable mirror. Additionally, the reflected light enters the monitoring module for real-time monitoring of the illumination beam.

[0039] A deformable mirror physically modulates the wavefront of the incident beam and reflects it. The illumination beam then passes through a quarter-wave plate, changing its polarization direction by 45°. At this point, the polarization direction of the illumination beam differs from that of the incident beam by 90°. Therefore, the illumination beam, after passing through the quarter-wave plate again, is reflected by a polarizing beam splitter onto a first beam splitter. This first beam splitter is a non-polarization-sensitive beam splitter and combiner, splitting the illumination beam with a transmission-to-reflection ratio of 99:1. One percent of the illumination beam is reflected into a wavefront sensor. The wavefront sensor detects the wavefront data of the beam and feeds it back to the deformable mirror, which modulates the illumination beam based on the data, optimizing the beam entering the mask.

[0040] The adaptive module of the present invention solves the problem of wavefront optimization and control of the illumination beam of the mask, improves the wavefront quality of the illumination beam, and thus effectively improves the exposure pattern quality of the mask.

[0041] In some other embodiments of this disclosure, the first beam splitter is a non-polarization-sensitive beam splitter and combiner prism. On the one hand, it splits the illumination beam strictly according to the transmission-to-reflection ratio of 99:1. On the other hand, it can reflect the visible indicator beam with a reflectivity of more than 50%, thereby realizing the beam combining of the illumination beam and the visible indicator beam.

[0042] In some embodiments of this disclosure, the primary mirror of the deformable mirror is a silver-coated reflector; the interior of the deformable mirror has a variable support, and the deformation of the deformable mirror can be achieved by the extension and retraction of the variable support, thereby realizing the physical modulation of the illumination beam incident on the deformable mirror.

[0043] In some embodiments of this disclosure, the wavefront sensor detects the wavefront information of the incident light and outputs the corresponding RMS wavefront value and PV value to the control software. The control software optimizes the variable strut extension and contraction of the deformable mirror through optimization calculations, optimizes the RMS wavefront value, and keeps the RMS wavefront value stable.

[0044] According to a fourth aspect of this disclosure, this disclosure provides a holographic exposure system, comprising: An exposure detection system used to adjust the orientation of a photomask; An exposure detection system for detecting the state of an illumination beam; An exposure detection and control system for optimizing the wavefront of the illumination beam; and, A photomask and an illumination source. In one specific embodiment, the illumination source is a laser.

[0045] In some embodiments of this disclosure, the holographic exposure system further includes: an optical switch, a half-wave plate, an electric reflector assembly, a beam expander, a variable aperture stop, and a homogenizing mirror; The illumination beam emitted by the illumination source passes sequentially through the light switch, half-wave plate, and motorized reflector group, then enters the homogenizing mirror through the variable aperture stop, and finally enters the exposure detection and control system.

[0046] In some embodiments of this disclosure, the tilt angle of the half-wave plate can be driven to rotate to change the polarization direction of the illumination beam. Specifically, the rotation position of the half-wave plate is as follows: when detecting the state of the illumination beam, the tilt angle of the half-wave plate is driven to rotate, and a polarizing beam splitter prism cooperates with the half-wave plate to split the illumination beam into transmitted light and reflected light; the transmitted light continues to be transmitted as the illumination beam, and the reflected light is reflected into the monitoring optical path of the monitoring module. When optimizing the wavefront of the illumination beam, the tilt angle of the half-wave plate is driven to rotate, and a polarizing beam splitter prism cooperates with the half-wave plate to split the illumination beam into transmitted light and reflected light; the transmitted light continues to be transmitted as the illumination beam to a quarter-wave plate for wavefront optimization; the reflected light is used for monitoring the illumination beam.

[0047] According to a fifth aspect of this disclosure, this disclosure provides a method for detecting incident light in a holographic exposure system, comprising: The deformable mirror inspection includes the following specific steps: When the holographic exposure system exposes the silicon wafer, the light beam, after being homogenized by the homogenizing mirror, enters the polarizing beam splitter. A portion of the light passes through the quarter-wave plate and is incident on the deformable mirror. During the deformable mirror inspection process, the deformable mirror is removed from the optical path, and the light beam is directly incident on the high-precision reflector after the deformable mirror is removed. Subsequently, the light beam is incident on the mask assembly to illuminate the mask. The change in the clarity of the mask diffraction image on the mask assembly before and after the deformable mirror is removed is observed to determine whether the deformable mirror is damaged.

[0048] The autocollimation module calibration includes the following specific steps: the visible indicator beam provided by the autocollimation module is reflected by the second beam splitter and then returns through the plane mirror to be incident on the autocollimation camera; the autocollimation camera can be driven to adjust its position so that the visible indicator beam hits the center position of the autocollimation camera, and the position of the autocollimation camera is adjusted until the position deviation of the autocollimation camera is controlled within 1 pixel.

[0049] Wavefront optimization of the illumination beam for the mask includes the following specific steps: the illumination beam passes sequentially through a polarizing beam splitter and a quarter-wave plate before being incident on a deformable mirror; the deformable mirror reflects the illumination beam, which then passes through the quarter-wave plate again and is reflected by the polarizing beam splitter. The reflected light is incident on the first beam splitter and is reflected into a wavefront sensor; the wavefront sensor detects the wavefront data of the beam and feeds the data back to the deformable mirror, which modulates the illumination beam based on the data to optimize the illumination beam entering the mask assembly.

[0050] The visible indicator beam and the illumination beam are combined by the following specific steps: the visible indicator beam emitted from the collimation module passes through the reflector group and enters the first beam splitter, forming a combined beam with the illumination beam. After the combined beam is reflected by the reflector, the position of the second positioning hole is adjusted accordingly so that the illumination beam can pass through the two second positioning holes; and the reflector group is adjusted accordingly so that the visible indicator beam can also pass through the two second positioning holes, thereby realizing the combination of the visible indicator beam and the illumination beam.

[0051] The illumination beam status detection includes the following specific steps: After the illumination beam passes through the polarizing beam splitter, a portion of the controlled beam is reflected. The reflected beam enters the monitoring optical path of the monitoring module. After the beam is split by the semi-transparent and semi-reflective beam splitter, it passes through the focusing lens and enters the power meter and the position monitoring camera respectively, so as to realize the monitoring of power and beam directionality.

[0052] In some embodiments of this disclosure, the above-described incident light detection method is applied to a holographic exposure system.

[0053] The exemplary embodiments disclosed herein may have some or all of the following beneficial effects: 1. The exposure detection system for adjusting the orientation of a mask provided in the exemplary embodiment of this disclosure includes: an autocollimation module, a beam combining module, and an illumination adjustment module. The autocollimation module provides a visible indicator beam (i.e., visible light) to the exposure detection system, enabling measurement of the incident light angle of the mask assembly and alignment of the illumination beam with the mask assembly. Then, the beam combining module detects the relative position of the illumination beam and the visible indicator beam to control their coaxiality. Finally, the illumination adjustment module controls the illumination beam to be perpendicularly incident on the mask, thereby enabling the detection of the illumination beam in the holographic exposure system by detecting the visible indicator beam, solving the problem of the lack of illumination beam detection in the prior art.

[0054] 2. In the exposure detection system for adjusting the mask orientation provided in the exemplary embodiment of this disclosure, the position of the autocollimating camera is adjusted by driving the autocollimating camera so that the visible indicator beam is centered on the autocollimating camera, thus calibrating the autocollimating module used for measurement. Afterwards, the autocollimating module can measure the incident light angle of the mask and also detect the illumination beam through the visible indicator beam, thus simply and efficiently aligning the illumination beam with the mask assembly.

[0055] 3. In the exposure detection system for adjusting the mask orientation provided in the exemplary embodiment of this disclosure, the beam combining module is used to combine the visible indicator beam and the illumination beam, controlling the illumination beam and the visible indicator beam to be coaxial. The beam combining module solves some assembly and adjustment problems caused by the invisibility of the illumination beam. Simultaneously, the visible indicator beam can reflect the orientation of the illumination beam, thereby facilitating the control of the orientation between the illumination beam and the mask assembly. Specifically, in this embodiment, the positions of the illumination beam and the visible indicator beam are controlled separately to ensure that the combined beam passes through two second positioning holes with preset apertures and spacing, thereby verifying whether the illumination beam and the visible indicator beam are coaxial. If they are not coaxial, the transmission of the illumination beam and the reflection position of the visible indicator beam are adjusted accordingly until they are coaxial.

[0056] 4. In the exposure detection system for adjusting the mask orientation provided in the exemplary embodiment of this disclosure, the illumination adjustment module is used to solve the problem of how to vertically incident the illumination beam onto the center of the mask. This embodiment also includes an orientation adjustment component for adjusting the mask angle and displacement. By adjusting the mask angle using the orientation adjustment component, the visible indicator beam is directed to the center position of the autocollimating camera, thus adjusting the angle between the mask assembly and the incident light; by adjusting the horizontal position of the mask assembly using the orientation adjustment component, the center position of the mask coincides with the visible indicator beam, thereby achieving complete alignment between the illumination beam and the center position of the mask.

[0057] 5. The exposure detection system for detecting the state of an illumination beam provided in the exemplary embodiment of this disclosure detects the state of the illumination beam through a monitoring module. Specifically, the power of the illumination beam is detected by a power meter, and the beam directionality of the illumination beam is detected by a position monitoring camera. By monitoring the state of the illumination beam during the exposure process through the above-mentioned monitoring module, it is possible to detect problems with the illumination beam in a timely manner, thereby improving the efficiency of photolithography exposure.

[0058] 6. In the exposure detection and control system for wavefront optimization of the illumination beam provided in the exemplary embodiment of this disclosure, the adaptive module modulates the beam incident on the mask, solving the problem of wavefront optimization and control of the illumination beam on the mask, greatly improving the wavefront quality of the illumination beam, thereby effectively improving the quality of the exposure pattern of the mask. Specifically, the wavefront data of the beam is detected by a wavefront sensor, and the data is fed back to the deformable mirror. The deformable mirror modulates the illumination beam according to the data, optimizing the illumination beam entering the mask assembly.

[0059] 7. In the exposure detection and control system for wavefront optimization of the illumination beam provided in the exemplary embodiment of this disclosure, the first beam splitter is a non-polarization-sensitive beam splitter and combiner prism. On the one hand, it strictly splits the illumination beam according to a transmission-to-reflection ratio of 99:1; on the other hand, it reflects the visible indicator beam with a reflectivity higher than 50%, thereby achieving beam combining of the illumination beam and the visible indicator beam. The first beam splitter can simultaneously achieve beam splitting of the illumination beam and beam combining of the illumination beam and the visible indicator beam. When the first beam splitter splits the illumination beam, the illumination beam is transmitted through the first beam splitter to the mask for exposure illumination, and the illumination beam is reflected by the first beam splitter to the wavefront sensor for wavefront data detection. By using the same first beam splitter to simultaneously achieve beam splitting and beam combining, the spatial structure layout of the exposure detection and control system can be effectively optimized. A single exposure detection system can simultaneously perform the functions of adjusting the mask orientation and optimizing the wavefront of the illumination beam.

[0060] 8. The holographic exposure system provided in the exemplary embodiments of this disclosure includes: an exposure detection system for adjusting the orientation of a mask, an exposure detection system for detecting the state of an illumination beam, and an exposure detection control system for optimizing the wavefront of the illumination beam. Therefore, the holographic exposure system has all the advantages of an exposure detection system.

[0061] 9. The holographic exposure system provided in the exemplary embodiments of this disclosure also includes a method for detecting deformable mirrors. This is because deformable mirrors are prone to causing a decline in exposure quality during long exposures. As a fragile optical component, the deformable mirror is one of the important factors affecting exposure quality. To investigate the impact of deformable mirror quality degradation, it is necessary to detect the deformable mirror. The specific idea for detecting deformable mirrors is to add a switching function between deformable mirrors and reflectors in the optical path. By moving the deformable mirror out of the optical path, the light beam is directly incident on a high-precision reflector, thus replacing the function of the deformable mirror. This is because if the deformable mirror malfunctions, it will not cause a change in the transmission direction of the optical path or energy attenuation. However, a malfunctioning deformable mirror will cause a reduction in the wavefront quality of the light spot, which will significantly reduce the clarity of the mask diffraction image. If the deformable mirror is moved out of the optical path, the light beam will directly incident on the high-precision reflector, pass through components such as a quarter-wave plate and a polarizing beam splitter, and finally incident on the mask assembly, thus illuminating the mask. The aforementioned high-precision reflector has sufficiently high surface accuracy to maintain the wavefront of the light spot to the maximum extent. If the deformable mirror malfunctions, replacing it with a high-precision reflector will significantly improve the clarity of the diffraction image on the mask. Technicians can determine whether there is a problem with the deformable mirror by observing the change in the clarity of the diffraction image on the mask.

[0062] It should be understood that the above general description and the following detailed description are exemplary and explanatory only, and are not intended to limit this disclosure. Attached Figure Description

[0063] The accompanying drawings, which form part of this disclosure, are used to provide a further understanding of the disclosure and to make other features, objects, and advantages of the disclosure more apparent. The illustrative embodiments of the disclosure, along with their descriptions, are used to explain the disclosure and do not constitute an undue limitation thereof. In the drawings: Figure 1 This is a schematic diagram of the holographic exposure system structure according to the embodiments of this disclosure; Figure 2 This is a schematic diagram of the optical path of the self-collimation module according to an embodiment of this disclosure; Figure 3 This is a schematic diagram of the optical path of the beam combining module according to an embodiment of this disclosure; Figure 4 This is a schematic diagram of the optical path of the adaptive module according to an embodiment of this disclosure.

[0064] Explanation of reference numerals in the attached figures: 1. Autocollimation module; 2. Visible indicator beam; 3. Second beam splitter; 4. Plane mirror; 5. Autocollimation camera; 6. Beam combiner module; 7. Illumination adjustment module; 8. Monitoring module; 9. Mask assembly; 10. Optical trap; 11. First positioning hole; 12. Mirror group; 13. First beam splitter; 14. Mirror; 15. Second positioning hole; 16. Alignment module; 17. Mask; 18. Attitude adjustment component; 19. Adaptive module 20. Power meter; 21. Position monitoring camera; 22. Half-wave plate; 23. Polarizing beam splitter; 24. Semi-transparent and semi-reflective beam splitter; 25. Focusing lens; 26. Quarter-wave plate; 27. Deformable mirror; 28. Wavefront sensor; 29. ​​Illumination source; 30. Optical switch; 31. Motorized mirror assembly; 32. Beam expander; 33. Variable aperture stop; 34. Beam homogenizer; 35. High-precision mirror; 36. Microscope objective; 37. Silicon wafer. Detailed Implementation

[0065] Exemplary embodiments will now be described more fully with reference to the accompanying drawings. However, these exemplary embodiments can be implemented in many forms and should not be construed as limited to the embodiments set forth herein; rather, they are provided so that this disclosure will be thorough and complete, and will fully convey the concept of the exemplary embodiments to those skilled in the art. The same reference numerals in the drawings denote the same or similar structures, and therefore detailed descriptions of them will be omitted. Furthermore, the drawings are merely illustrative of this disclosure and are not necessarily drawn to scale.

[0066] Although relative terms such as "upper" and "lower" are used in this specification to describe the relative relationship of one component of an icon to another, these terms are used only for convenience, such as according to the orientation of the examples in the accompanying drawings. It is understood that if the device of the icon is flipped so that it is upside down, the component described as "upper" will become the component described as "lower." When a structure is "upper" of another structure, it may mean that the structure is integrally formed on the other structure, or that the structure is "directly" mounted on the other structure, or that the structure is "indirectly" mounted on the other structure through another structure.

[0067] The terms “a,” “one,” “the,” and “at least one” are used to indicate the existence of one or more elements / components / etc.; the terms “including” and “having” are used to indicate an open-ended inclusion and to mean that there may be other elements / components / etc. in addition to the listed elements / components / etc.; the terms “first” and “second” are used only as markers and are not a limitation on the number of objects.

[0068] Furthermore, the terms "set up," "equipped with," "connected," and "fixed" should be interpreted broadly. For example, "connection" can be a fixed connection, a detachable connection, or an integral structure; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, or an internal connection between two devices, components, or parts. Those skilled in the art can understand the specific meaning of the above terms in this disclosure according to the specific circumstances.

[0069] In addition, the term "multiple" should mean two or more.

[0070] It should be noted that, unless otherwise specified, the embodiments and features described in this disclosure can be combined with each other. This disclosure will now be described in detail with reference to the accompanying drawings and embodiments.

[0071] Example 1 Existing technologies lack advance detection and control of the illumination beam. Common position measurement systems in the prior art detect the illumination beam by using a measuring surface with a grid pattern on a stage of the mask and a readout head that illuminates the measuring surface with the beam. These systems receive the return beam from the measuring surface to obtain the stage position information of the mask. However, because the illumination beam is invisible, existing technologies cannot directly detect parameters such as its position and directionality, let alone control it. Therefore, when exposure quality problems occur, it is impossible to directly determine the factors causing the exposure problem, and it is also impossible to control the illumination beam to solve the problem.

[0072] See Figure 1 The diagram shows a schematic of a holographic exposure system. To address the aforementioned technical problems, this embodiment specifically discloses an exposure detection system for adjusting the orientation of a holographic mask exposure system. The holographic mask exposure system includes a mask 17 and an illumination source 29; the illumination source 29 is preferably a laser, used to emit an illumination beam for exposure. The exposure detection system includes: Self-collimation module 1, such as Figure 2The diagram shows the optical path of the autocollimation module. The autocollimation module 1 provides a visible indicator beam 2 and detects the perpendicularity deviation between the surface of the optical element and the incident light; wherein the visible indicator beam 2 is visible light; the autocollimation module 1 includes: an autocollimation camera 5 and two spaced first positioning holes 11. The autocollimation camera 5 receives the visible indicator beam 2 and is used to detect the perpendicularity deviation between the surface of the mask 17 and the illumination beam. There are two spaced first positioning holes 11 through which the visible indicator beam 2 passes to calibrate its position and ensure collimation. In a preferred embodiment, the autocollimation module 1 further includes: a second beam splitter 3 and a plane mirror 4. The visible indicator beam 2 provided by the autocollimation module 1 is reflected by the second beam splitter 3, then returns via the plane mirror 4 and is incident on the autocollimation camera 5. The autocollimation camera 5 can be driven to adjust its position so that the visible indicator beam 2 hits the center position of the autocollimation camera 5, thereby completing the calibration of the autocollimation module. The positional deviation of the visible indicator beam 2 hitting the center position of the autocollimation camera 5 is controlled within one pixel, thus ensuring the calibration accuracy of the autocollimation module 1 in the exposure detection system. Of course, this embodiment does not specifically limit the positional deviation between the visible indicator beam 2 and the center position of the autocollimation camera 5. In other embodiments, the positional deviation of the visible indicator beam 2 hitting the center position of the autocollimation camera 5 can also be controlled within two pixels or other pixel values ​​as needed. Further, in this preferred embodiment, the specific calibration structure of the autocollimating camera 5 is as follows: the autocollimating module 1 includes a second beam splitter 3, a plane mirror 4, an optical trap 10, and the autocollimating camera 5; when the visible indicator beam 2 is incident on the second beam splitter 3, the visible indicator beam 2 is split. The transmitted light after the visible indicator beam 2 is split is incident on the optical trap 10 as stray light and is absorbed; the reflected light after the visible indicator beam 2 is split passes through two first positioning holes 11 with a distance between them. The aperture of the first positioning hole 11 matches the diameter of the incident light to ensure the collimation of the beam; wherein, the aperture of the first positioning hole 11 is close to the diameter of the incident light, thereby ensuring the collimation of the beam. Of course, the aperture size and spacing of the two first positioning holes 11 can be adjusted as needed. Furthermore, the number of first positioning holes 11 can also be three or more. The reflected light from the first positioning hole 11 returns via the plane mirror 4 and strikes the autocollimating camera 5. The center position of the autocollimating camera 5 is adjusted accordingly to align the visible indicator beam 2 with the center position of the autocollimating camera 5. The autocollimating module 1 enables the measurement of the incident light angle on the mask 17 and also fulfills the requirement of providing a visible indicator beam for the illumination beam, achieving simple and efficient alignment between the illumination beam and the mask 17. Furthermore, the spaced first positioning holes 11 ensure simple and efficient beam collimation.Of course, this embodiment does not specifically limit the structure of the beam combining module 6. In other embodiments, the beam combining of the visible indicator beam 2 and the illumination beam can also be achieved by using a dichroic mirror to combine the wavelengths of the beams. Alternatively, the polarization beam combining of the visible indicator beam 2 and the illumination beam can be achieved by using a polarizing beam splitter and a waveplate.

[0073] Bundle module 6, such as Figure 3 The diagram shows the optical path of the beam combining module. The beam combining module 6 is used to detect the relative position of the illumination beam and the visible indicator beam 2, thereby controlling the coaxiality of the illumination beam and the visible indicator beam 2. The beam combining module 6 includes: a first beam splitter 13 and two spaced second positioning holes 15. The first beam splitter 13 receives the visible indicator beam 2 and the illumination beam, and is used to combine them. There are two spaced second positioning holes 15, which allow the illumination beam and the visible indicator beam 2 to pass through respectively, to calibrate their positions and ensure coaxiality. In a preferred embodiment, the beam combining module 6 further includes: a reflector group 12 and a reflector 14. The visible indicator beam 2 emitted from the collimation module 1 passes through the reflector group 12 and enters the first beam splitter 13, forming a combined beam with the illumination beam. After reflection by the reflector 14, the position of the second positioning holes 15 is adjusted accordingly so that the illumination beam can pass through both second positioning holes 15; and the reflector group 12 is adjusted accordingly so that the visible indicator beam 2 can also pass through both second positioning holes 15, thus completing the beam combining. After beam combining, the visible indicator beam 2 and the illumination beam are coaxial. In a preferred embodiment, the two second positioning holes 15 are positioning holes with the same aperture and a spacing of 1m. Of course, the aperture size and spacing of the two second positioning holes 15 can be adjusted to other values ​​as needed. Furthermore, the number of second positioning holes 15 can be three or more. The aforementioned beam combining module 6 solves the problem of inability to install and adjust the illumination beam because it is invisible. By combining the visible indicator beam 2 and the illumination beam through the beam combining module 6, the attitude of the illumination beam can be reflected by the visible indicator beam 2, thereby facilitating the control of the attitude and position between the illumination beam and the mask 17.

[0074] The illumination adjustment module 7 is used to control the vertical incidence of the illumination beam onto the center position of the mask 17 in the mask assembly 9. For example... Figure 1As shown, the illumination adjustment module 7 includes an alignment module 16 and an attitude adjustment component 18. The alignment module 16 receives the visible indicator beam 2 and observes the relative position of the mask 17 and the visible indicator beam 2. The attitude adjustment component 18 is used to adjust the position of the mask 17 so that the preset position of the mask 17 coincides with the visible indicator beam 2. In a preferred embodiment, the attitude adjustment component 18 is integrated on the mask 17. The mask 17 and the attitude adjustment component 18 for adjusting the angle and displacement of the mask 17 constitute the mask assembly 9. When the visible indicator beam 2 passes through the first beam splitter prism 13 and the alignment module 16 and is incident on the mask assembly 9; after the visible indicator beam 2 returns to the autocollimation module 1 via the original path, the attitude adjustment component 18 adjusts the angle of the mask 17 so that the visible indicator beam 2 hits the center position of the autocollimation camera 5, thereby completing the adjustment of the angle between the mask assembly 9 and the incident light. Furthermore, the alignment module 16 in the illumination adjustment module 7 observes the relative position of the center of the mask 17 and the visible indicator beam 2, and the attitude adjustment component 18 adjusts the horizontal position of the mask assembly 9 to align the center of the mask 17 with the visible indicator beam 2. Since the visible indicator beam 2 and the illumination beam are coaxial, the illumination beam and the center of the mask 17 are completely aligned. The illumination adjustment module 7 receives the visible indicator beam 2 through the alignment module 16, thereby observing the relative position of the mask 17 and the visible indicator beam 2. In conjunction with the attitude adjustment component 18, the position of the mask 17 is adjusted to align the preset position of the mask 17 with the visible indicator beam 2. The illumination adjustment module 7 effectively ensures that the illumination beam is perpendicularly incident on the center of the mask 17, improving the efficiency of photolithography exposure.

[0075] In a preferred embodiment, the verticality detection calculation formula of the self-collimation module is as follows: , Where θ is the angle between the mask 17 and the incident light, σ is the pixel size of the autocollimating camera 5, n is the number of pixels that the centroid of the incident light deviates from the center of the autocollimating camera 5, and L is the distance from the autocollimating module 1 to the mask 17; according to the above formula, it can be seen that the detection data of the autocollimating module 1 is actually twice the angle deviation between the mask 17 and the incident light. The perpendicularity of the autocollimating module can be accurately detected by the above perpendicularity detection calculation formula.

[0076] In another preferred embodiment, the optical trap 10 in the self-collimating module 1 is used to ensure that the incident light beam cannot be reflected. The specific structure of the optical trap 10 is a serrated conical structure coated with black matte paint.

[0077] In another preferred embodiment, the plane mirror 4 in the autocollimation module 1 has a silver-plated film and a protective film. The plane mirror 4 is not limited by the incident angle and has high reflectivity.

[0078] In another preferred embodiment, the second beam splitter 3 in the self-collimation module 1 is a semi-transparent and semi-reflective prism that does not require polarization of the incident light, so as to achieve a 50:50 beam splitting ratio. The prism material of the second beam splitter 3 is fused silica, which is formed by curing two right-angle prisms through a photopolymerization process.

[0079] In another preferred embodiment, the autocollimating camera 5 in the autocollimating module 1 has a camera target surface size of 4 / 3 inch to ensure reception of incident light. The center position of the autocollimating camera 5 is adjusted by control programming software. The autocollimating camera 5 is driven to move up, down, left, and right to change its center position, controlling the deviation between the visible indicator beam 2 and the center of the autocollimating camera 5 within 1 pixel. Of course, in this embodiment, the camera target surface size of the autocollimating camera 5 can also be adjusted to other sizes as needed.

[0080] In a preferred embodiment, the mask assembly 9 of the self-collimation module includes: an integrated mask 17 and an attitude adjustment component 18 for adjusting the angle and displacement of the mask 17. The attitude adjustment component 18 can perform coarse and fine adjustments on the mask 17. Figure 1 As shown, the aforementioned attitude adjustment component 18 includes a capacitive sensor disposed on the mask assembly 9. The capacitive sensor is used to measure the distance between the mask 17 and the silicon wafer 37 in real time to detect the positional state between the mask assembly 9 and the silicon wafer 37. In this embodiment, the silicon wafer 37 can be moved horizontally. The diffraction image of the mask 17 can be observed through the microscope objective 36. After the imaging quality is determined, the silicon wafer 37 is moved into the optical path. Finally, exposure is achieved on the silicon wafer 37. The aforementioned capacitive sensor can accurately measure the positional state between the mask 17 and the silicon wafer 37 on the mask assembly 9 in real time.

[0081] In another preferred embodiment, the first beam splitter 13 of the self-collimation module is a non-polarization sensitive beam splitter and beam combiner prism, which is formed by bonding two right-angle prisms together using an optical adhesive process. The material of the first beam splitter 13 is ultraviolet fused silica, and the coating surface is designed to have a transmittance-to-reflection ratio of 99:1 corresponding to the illumination beam. It is visible that the reflectivity of the indicator beam 2 on the coating surface is ≥50%.

[0082] Example 2 See Figure 1The diagram shows a schematic of the holographic exposure system. In this embodiment, an exposure detection system for detecting the state of an illumination beam is also specifically disclosed, including: the exposure detection system in Embodiment 1; and a monitoring module 8. The monitoring module 8 is used to detect the state of the illumination beam.

[0083] The monitoring module 8 includes a power meter 20 and a position monitoring camera 21. The power meter 20 is used to detect the power of the illumination beam. The beam focus of the power meter 20 is located outside the detector target surface, thereby avoiding the beam from being too concentrated and affecting the power measurement accuracy. The position monitoring camera 21 is used to detect the beam directionality of the illumination beam. Of course, this embodiment does not specifically limit the components of the monitoring module 8. In other embodiments, the monitoring module 8 may only contain one of the power meter 20 and the position monitoring camera 21.

[0084] In a specific embodiment, such as Figure 1 As shown, the monitoring module 8 includes a half-wave plate 22 and a polarizing beam splitter 23, as well as a semi-transparent, semi-reflective beam splitter 24 and a focusing lens 25. The half-wave plate 22 controls the polarization direction of the illumination beam; when the monitoring module 8 detects the state of the illumination beam, the illumination beam, whose polarization direction has been changed by the half-wave plate 22, illuminates the polarizing beam splitter 23. The polarizing beam splitter 23 works in conjunction with the half-wave plate 22 to split the illumination beam into transmitted and reflected light; the transmitted light continues to propagate as the illumination beam, while the reflected light is reflected into the monitoring optical path of the monitoring module 8. The semi-transparent, semi-reflective beam splitter 24 receives the illumination beam reflected by the polarizing beam splitter 23, thus splitting the illumination beam. The focusing lens 25 is positioned in the light path of the power meter 20 and receives the illumination beam split by the semi-transparent, semi-reflective beam splitter 24, converging the illumination beam onto the power meter 20. A focusing lens 25 is positioned in the light path of the position monitoring camera 21 to receive the illumination beam split by the semi-transparent beam splitter 24 and converge it to the position monitoring camera 21. In this embodiment, firstly, the angle of the half-wave plate 22 is adjusted to control the polarization direction of the illumination beam. During the operation of the monitoring module 8, the specific optical path is as follows: after the illumination beam changes its polarization direction through the half-wave plate 22, it illuminates the polarization beam splitter 23. A portion of the controlled beam is reflected by the polarization beam splitter 23, and the reflected beam enters the monitoring optical path of the monitoring module 8. After being split by the semi-transparent beam splitter 24, the beam passes through the focusing lens 25 and enters the power meter 20 and the position monitoring camera 21 respectively, thereby achieving monitoring of power and beam directivity. When the monitoring module 8 and the illumination adjustment module 7 are used together, it can ensure that the illumination beam is perpendicularly incident on the center position of the mask 17. It can also simultaneously monitor the state of the illumination beam during the exposure process, which helps to detect problems with the illumination beam in a timely manner, thereby improving the efficiency of photolithography exposure.

[0085] Example 3 See Figure 4 The diagram shows the optical path of the adaptive module. In this embodiment, an exposure detection and control system for optimizing the wavefront of an illumination beam is also specifically disclosed, including: the exposure detection system in Embodiment 1; and an adaptive module 19. The adaptive module 19 includes: a wavefront sensor 28 and a deformable mirror 27. The wavefront sensor 28 is used to detect the wavefront data of the illumination beam and send the wavefront data to the deformable mirror 27. The deformable mirror 27 is used to receive the wavefront data and modulate the illumination beam, optimizing the wavefront of the illumination beam entering the mask 17. The adaptive module 19 is used to modulate the beam incident on the mask 17 and optimize the wavefront to improve the quality of the illumination beam incident on the mask, thereby solving the problem of the inability to control and optimize the wavefront of the illumination beam in the prior art. In a preferred embodiment, the adaptive module 19 further includes: a half-wave plate 22, a polarizing beam splitter 23, a quarter-wave plate 26, and a first beam splitter 13. Half-wave plate 22 is used to control the polarization direction of the illumination beam. When the adaptive module 19 performs wavefront optimization on the illumination beam, the illumination beam, whose polarization direction has been changed by half-wave plate 22, illuminates the polarizing beam splitter 23. The polarizing beam splitter 23 works in conjunction with half-wave plate 22 to split the illumination beam into transmitted and reflected light. The transmitted light, as the illumination beam, continues to be transmitted to quarter-wave plate 26 for wavefront optimization. Quarter-wave plate 26 rotates the polarization direction of the transmitted light, directing the transmitted light, which serves as the illumination beam, to deformable mirror 27. Deformable mirror 27 reflects the illumination beam that has passed through quarter-wave plate 26. The reflected illumination beam, after its polarization direction is changed again by quarter-wave plate 26, enters the first beam splitter 13. The first beam splitter 13 splits the illumination beam reflected by deformable mirror 27. The illumination beam is transmitted through the first beam splitter 13 to mask 17 for exposure illumination, and reflected by the first beam splitter 13 to wavefront sensor 28 to detect wavefront data.

[0086] In this embodiment, the specific optical path for optimizing the illumination beam entering the mask 17 is as follows: the illumination beam emitted by the illumination source 29 passes sequentially through the polarizing beam splitter 23 and the quarter-wave plate 26 before being incident on the deformable mirror 27. The polarizing beam splitter 23 works in conjunction with the half-wave plate 22, splitting the illumination beam into transmitted and reflected light. The transmitted light continues to propagate as the illumination beam to the quarter-wave plate 26. The quarter-wave plate 26 rotates the polarization direction of the transmitted light by 45°, allowing the transmitted light, serving as the illumination beam, to be incident on the deformable mirror 27. Additionally, the reflected light enters the monitoring module 8 for real-time monitoring of the illumination beam.

[0087] The deformable mirror 27 physically modulates the wavefront of the incident beam and reflects the illumination beam. The illumination beam then passes through the quarter-wave plate 26, changing its polarization direction by 45°. At this point, there is a 90° difference in polarization direction between the illumination beam and the incident beam. Therefore, the illumination beam, after passing through the quarter-wave plate 26 again, is reflected by the polarizing beam splitter 23 onto the first beam splitter 13. This first beam splitter 13 is a non-polarization-sensitive beam splitter and combiner prism, splitting the illumination beam according to a transmission-to-reflection ratio of 99:1. One percent of the illumination beam is reflected into the wavefront sensor 28. The wavefront sensor 28 detects the wavefront data of the beam and feeds the data back to the deformable mirror 27. The deformable mirror 27 modulates the illumination beam based on the data, optimizing the illumination beam entering the mask 17. The adaptive module 19, through the deformable mirror 27, modulates the illumination beam based on the wavefront data detected by the wavefront sensor 28, optimizing the illumination beam entering the mask 17. This invention solves the problem of lacking wavefront optimization and control of the illumination beam of the mask in the existing technology, improves the wavefront quality of the illumination beam, and thus effectively improves the exposure pattern quality of the mask 17.

[0088] In a preferred embodiment, the primary mirror of the deformable mirror 27 is a silver-coated reflector; the deformable mirror 27 has a variable support column inside, and the deformation of the deformable mirror 27 can be achieved by the extension and retraction of the variable support column, thereby physically modulating the illumination beam incident on the deformable mirror 27. Of course, in this embodiment, the deformation of the deformable mirror 27 can also be achieved by the extension and retraction of other components such as push rods.

[0089] In another preferred embodiment, wavefront sensor 28 detects the wavefront information of the incident light and outputs the corresponding RMS wavefront value and PV value to the control software. The control software optimizes the calculations to control the extension and retraction of the variable strut of deformable mirror 27, thereby optimizing the RMS wavefront value and maintaining its stability. The wavefront-modulated and optimized beam directly illuminates the mask 17 on the mask assembly 9.

[0090] Example 4 See Figure 1The diagram shows a holographic exposure system with exposure detection and control functions. This embodiment specifically discloses a holographic exposure system, including: the exposure detection system for adjusting the mask orientation described in Embodiment 1, the exposure detection system for detecting the state of the illumination beam described in Embodiment 2, the exposure detection and control system for optimizing the wavefront of the illumination beam described in Embodiment 3, as well as a mask 17 and an illumination source 29. In a preferred embodiment, the holographic exposure system further includes: a light switch 30, a half-wave plate 22, an electric reflector group 31, a beam expander 32, a variable aperture stop 33, and a homogenizing mirror 34. The illumination beam emitted by the illumination source 29 passes sequentially through the light switch 30, the half-wave plate 22, and the electric reflector group 31, then passes through the variable aperture stop 33 and enters the homogenizing mirror 34. The homogenized illumination beam then enters the exposure detection and control system.

[0091] In the aforementioned holographic exposure system, the tilt angle of the half-wave plate 22 can be driven to rotate to change the polarization direction of the illumination beam. Specifically, the rotation position of the half-wave plate 22 is as follows: When detecting the state of the illumination beam, the tilt angle of the half-wave plate 22 is driven to rotate, and the polarizing beam splitter 23 cooperates with the half-wave plate 22 to split the illumination beam into transmitted light and reflected light; the transmitted light continues to be transmitted as the illumination beam, and the reflected light is reflected into the monitoring optical path of the monitoring module 8. When optimizing the wavefront of the illumination beam, the tilt angle of the half-wave plate 22 is driven to rotate, and the polarizing beam splitter 23 cooperates with the half-wave plate 22 to split the illumination beam into transmitted light and reflected light; the transmitted light continues to be transmitted as the illumination beam to the quarter-wave plate 26 for wavefront optimization; the reflected light is used for monitoring the illumination beam. The rotatable half-wave plate 22 can simultaneously meet the polarization requirements of the illumination beam when the illumination beam state is detected by the monitoring module 8 in Embodiment 2; and the polarization requirements of the illumination beam when the wavefront of the illumination beam is optimized by the wavefront sensor 28 and the deformable mirror 27 in Embodiment 3.

[0092] Example 5 See Figure 1 The diagram shows the structure of a holographic exposure system. In this embodiment, a method for detecting incident light in a holographic exposure system is specifically disclosed, including the following detection method: The deformation mirror 27 inspection includes the following steps: When the holographic exposure system exposes the silicon wafer 37, the light beam, after being homogenized by the homogenizing mirror 34, enters the polarizing beam splitter 23. Part of the light passes through the quarter-wave plate 26 and is incident on the deformation mirror 27. During the inspection of the deformation mirror 27, the deformation mirror 27 is removed from the optical path. After the deformation mirror 27 is removed, the light beam is directly incident on the high-precision reflector 35. The reflected light passes through the quarter-wave plate 26 and the polarizing beam splitter 23 again, and then is reflected onto the first beam splitter 13. Part of the light beam enters the wavefront sensor 28. The wavefront sensor 28 and the deformation mirror 27 form a feedback closed loop to optimize the wavefront of the light beam. The other part of the light beam passes through the first beam splitter 13 and is incident on the mask assembly 9 to illuminate the mask 17. The change in the clarity of the diffraction image of the mask 17 on the mask assembly 9 before and after the deformation mirror 27 is removed is observed to determine whether the deformation mirror 27 is damaged. Because the deformable lens 27 is a fragile optical component, it is a crucial factor affecting exposure quality. The aforementioned method for inspecting the deformable lens 27 allows technicians to check its quality by observing changes in the sharpness of the diffraction image on the mask 17.

[0093] Self-collimation module 1 calibration, such as Figure 2 The schematic diagram of the optical path of the autocollimating module shown illustrates the following steps for calibrating the autocollimating module 1: The visible indicator beam 2 provided by the autocollimating module 1 is reflected by the second beam splitter 3, then returns via the plane mirror 4 and is incident on the autocollimating camera 5; the autocollimating camera 5 can be driven to adjust its position so that the visible indicator beam 2 hits the center of the autocollimating camera 5, and the position of the autocollimating camera 5 is adjusted until the positional deviation of the autocollimating camera 5 is controlled within 1 pixel. The calibrated autocollimating module 1 can measure the incident light angle of the mask 17 and can also detect the illumination beam through the visible indicator beam 2, thus aligning the illumination beam with the mask 17 simply and efficiently.

[0094] For wavefront optimization of the mask illumination beam, see [link to relevant documentation]. Figure 4The diagram shows the optical path of the adaptive module. Wavefront optimization of the mask illumination beam includes the following steps: the illumination beam passes sequentially through a polarizing beam splitter 23 and a quarter-wave plate 26 before being incident on a deformable mirror 27; the deformable mirror 27 reflects the illumination beam, which then passes again through the quarter-wave plate 26 and is reflected by the polarizing beam splitter 23. The reflected light is incident on the first beam splitter 13 and enters the wavefront sensor 28; the wavefront sensor 28 detects the wavefront data of the beam and feeds the data back to the deformable mirror 27, which modulates the illumination beam according to the data, optimizing the illumination beam entering the mask assembly 9. Through the coordinated operation of the wavefront sensor 28 and the deformable mirror 27, the deformable mirror 27 can modulate the illumination beam according to the data provided by the wavefront sensor 28, optimizing the illumination beam entering the mask 17, greatly improving the wavefront quality of the illumination beam, and thus effectively improving the quality of the exposure pattern on the mask.

[0095] It is visible that the indicator beam 2 and the illumination beam are combined, such as Figure 3 The diagram shows the optical path of the beam combining module. The beam combining of the visible indicator beam 2 and the illumination beam includes the following steps: The visible indicator beam 2 emitted from the collimation module 1 passes through the reflector group 12 and enters the first beam splitter prism 13, forming a beam combiner with the illumination beam. After reflection by the reflector 14, the position of the second positioning holes 15 is adjusted accordingly so that the illumination beam can pass through both second positioning holes 15; and the reflector group 12 is adjusted accordingly so that the visible indicator beam 2 can also pass through both second positioning holes 15, thus achieving beam combining of the visible indicator beam 2 and the illumination beam. Through the above beam combining steps, the beam combining of the visible indicator beam 2 and the illumination beam is achieved, controlling the illumination beam and the visible indicator beam 2 to be coaxial, and solving the adjustment problem caused by the invisibility of the illumination beam.

[0096] Illumination beam status detection, such as Figure 1 As shown, the illumination beam state detection includes the following steps: After the illumination beam passes through the polarizing beam splitter 23, a portion of the controlled beam is reflected. The reflected beam enters the monitoring optical path of the monitoring module 8. After being split by the semi-transparent and semi-reflective beam splitter 24, the beam passes through the focusing lens 25 and enters the power meter 20 and the position monitoring camera 21 respectively, thereby realizing the monitoring of power and beam directionality. The power meter 20 and the position monitoring camera 21 can monitor the illumination beam state during the exposure process of the holographic exposure system, which helps to detect problems with the illumination beam in a timely manner, thereby improving the efficiency of photolithography exposure.

[0097] In a preferred embodiment, the above-described incident light detection method is applied to the holographic exposure system of Example 4.

[0098] Other embodiments of this disclosure will readily occur to those skilled in the art upon consideration of the specification and practice of the embodiments thereof. This disclosure is intended to cover any variations, uses, or adaptations of this disclosure that follow the general principles of this disclosure and include common knowledge or customary techniques in the art not claimed herein. The specification and embodiments are to be considered exemplary only, and the true scope and spirit of this disclosure are indicated by the appended claims.

Claims

1. An exposure detection system for adjusting the orientation of a holographic mask, used in a holographic mask exposure system, the holographic mask exposure system comprising: Mask (17) and illumination source (29); The illumination source (29) is used to emit an illumination beam for exposure, characterized in that the exposure detection system includes: Indicator light source, used to emit a visible indicator beam (2); The beam combining module (6) is configured to receive the illumination beam and the visible indicator beam (2), combine the illumination beam and the visible indicator beam (2), and direct the combined beam toward the mask (17) to be tested. The self-collimation module (1) is configured to receive the combined beam reflected back from the mask (17) and detect the perpendicularity deviation between the mask (17) and the combined beam by analyzing the position of the reflected spot of the visible indicator beam (2). The illumination adjustment module (7) includes an alignment module (16) and an attitude adjustment component (18); the attitude adjustment component (18) is configured to adjust the angle of the mask (17) so that the mask (17) is perpendicular to the beam combining beam; the alignment module (16) is configured to detect the horizontal relative position of the center of the mask (17) and the visible indicator beam (2); the attitude adjustment component (18) is configured to adjust the horizontal position of the mask (17) so that the center of the mask (17) coincides with the visible indicator beam (2).

2. The exposure detection system for adjusting the orientation of a photomask according to claim 1, characterized in that, The beam combining module (6) includes a first beam splitter (13), which is configured to transmit the illumination beam, reflect the visible indicator beam (2), and reflect the visible indicator beam (2) into the same optical path as the illumination beam to form the beam combining beam.

3. The exposure detection system for adjusting the orientation of a photomask according to claim 2, characterized in that, The autocollimation module (1) includes: a second beam splitter (3) and an autocollimation camera (5). The second beam splitter (3) is disposed in the optical path of the visible indicator beam (2) and is used to reflect the visible indicator beam (2) emitted by the indicator light source to the beam combining module (6) for beam combining. The second beam splitter (3) is also used to transmit the visible indicator beam (2) reflected back from the surface of the mask plate (17) to be tested to the autocollimation camera (5). The autocollimating camera (5) is used to receive the visible indicator beam (2) reflected back from the surface of the mask (17) and obtain its spot position, converting the angle deviation into a position deviation signal.

4. The exposure detection system for adjusting the orientation of a photomask according to claim 3, characterized in that, The autocollimation module (1) further includes: a plane mirror (4) and at least two first positioning holes (11) arranged at intervals along the optical axis. The at least two first positioning holes (11) are used to allow the visible indicator beam (2) to pass through, so as to calibrate the position of the visible indicator beam (2) and ensure that the visible indicator beam (2) is collimated; The autocollimation module (1) has a calibration stage, in which the plane mirror (4) is placed at the measurement position of the autocollimation module (1) and the plane mirror (4) has a known normal direction; The plane mirror (4) is used to reflect the visible indicator beam (2) reflected by the second beam splitter (3) back along the original incident light path; the visible indicator beam (2) passes through the first positioning hole (11) to calibrate the position, and then enters the autocollimating camera (5) after passing through the second beam splitter (3); During the calibration phase, the position of the autocollimating camera (5) is adjusted so that the spot of the visible indicator beam (2) hits the center of the autocollimating camera (5) and the deviation is controlled within the preset pixel value. At this time, the spot position is calibrated as the zero position of angle measurement.

5. The exposure detection system for adjusting the orientation of a photomask according to claim 4, characterized in that, The self-collimation module (1) further includes an optical trap (10), which receives the transmitted light after it has been split by the second beam splitter (3). The transmitted light is absorbed after being incident on the optical trap (10) as stray light.

6. The exposure detection system for adjusting the orientation of a photomask according to claim 5, characterized in that, The light trap (10) is a serrated conical structure coated with black matte paint; and / or, The second beam splitter (3) is a semi-transparent, semi-reflective prism that does not require polarization of the incident light, in order to achieve a 50:50 beam splitting ratio. The prism material of the second beam splitter (3) is fused silica, which is formed by two right-angle prisms cured by photopolymerization. And / or, The plane mirror (4) has a silver coating and a protective film; and / or, The verticality calculation formula for the self-collimation module (1) is as follows: ， Where θ is the angle between the mask (17) and the incident light, σ is the pixel size of the autocollimating camera (5), n is the number of pixels that the centroid of the incident light deviates from the center of the autocollimating camera (5), and L is the distance from the autocollimating module (1) to the mask (17); and / or, The autocollimating camera (5) is a large target area camera; the center position of the autocollimating camera (5) is adjusted by the control programming software. The autocollimating camera (5) is driven to move along the horizontal and vertical directions to change its center position in order to control the deviation between the visible indicator beam (2) and the center of the autocollimating camera (5).

7. The exposure detection system for adjusting the orientation of a photomask according to any one of claims 3 to 6, characterized in that, The beam combining module (6) further includes: a reflector (14) and at least two second positioning holes (15) spaced apart along the optical axis; the edges of the second positioning holes (15) are provided with fluorescent material, which can emit visible light when illuminated by the illumination beam; The at least two second positioning holes (15) are used to allow the illumination beam and the visible indicator beam (2) to pass through, so as to calibrate the position of the illumination beam and the visible indicator beam (2) and ensure that the illumination beam and the visible indicator beam (2) are coaxial.

8. The exposure detection system for adjusting the orientation of a photomask according to claim 1, characterized in that, The attitude adjustment component (18) includes: an angle adjustment structure for adjusting the tilt angle of the mask (17), and a position adjustment structure for adjusting the displacement position of the mask (17).

9. The exposure detection system for adjusting the orientation of a photomask according to claim 8, characterized in that, The attitude adjustment component (18) further includes a capacitive sensor disposed on the mask (17), the capacitive sensor being used to measure the distance between the mask (17) and the silicon wafer (37) in real time to detect the positional state between the mask (17) and the silicon wafer (37).

10. An exposure detection system for detecting the state of an illumination beam, characterized in that, include: An exposure detection system for adjusting the orientation of a photomask, as described in any one of claims 1 to 9; as well as, A monitoring module (8) is used to detect the status of the illumination beam; the monitoring module (8) includes: a power meter (20) and / or a position monitoring camera (21). The power meter (20) receives the illumination beam to detect the power of the illumination beam; The location monitoring camera (21) receives the illumination beam to detect the beam directionality of the illumination beam.

11. The exposure detection system for detecting the state of an illumination beam according to claim 10, characterized in that, The monitoring module (8) also includes: a half-wave plate (22) and a polarizing beam splitter (23), as well as a semi-transparent and semi-reflective beam splitter (24) and a focusing lens (25). The half-wave plate (22) is used to control the polarization direction of the illumination beam; when the monitoring module (8) performs state detection on the illumination beam, the illumination beam whose polarization direction is changed by the half-wave plate (22) illuminates the polarization beam splitter (23). The polarizing beam splitter (23) works in conjunction with the half-wave plate (22). The polarizing beam splitter (23) is used to split the illumination beam into transmitted light and reflected light. The transmitted light continues to be transmitted as the illumination beam, and the reflected light is reflected into the monitoring optical path of the monitoring module (8). The semi-transparent and semi-reflective beam splitter (24) is used to receive the illumination beam reflected by the polarizing beam splitter (23) and split the illumination beam. The focusing lens (25) is disposed on the light path of the power meter (20) to receive the illumination beam after it is split by the semi-transparent and semi-reflective beam splitter (24) and to converge the illumination beam to the power meter (20); and / or, the focusing lens (25) is disposed on the light path of the position monitoring camera (21) to receive the illumination beam after it is split by the semi-transparent and semi-reflective beam splitter (24) and to converge the illumination beam to the position monitoring camera (21).

12. An exposure detection and control system for optimizing the wavefront of an illumination beam, characterized in that, include: An exposure detection system for adjusting the orientation of a photomask, as described in any one of claims 1 to 9; as well as, An adaptive module (19) is used to modulate the beam incident on the mask (17) to improve the quality of the illumination beam incident on the mask (17); The adaptive module (19) includes a wavefront sensor (28) and a deformable mirror (27); the wavefront sensor (28) is used to detect the wavefront data of the illumination beam and send the wavefront data to the deformable mirror (27); the deformable mirror (27) is used to receive the wavefront data and adjust it to a surface shape opposite to the wavefront distortion to perform phase compensation on the illumination beam entering the mask (17).

13. The exposure detection and control system for optimizing the wavefront of an illumination beam according to claim 12, characterized in that, The adaptive module (19) further includes: a half-wave plate (22), a polarizing beam splitter (23), a quarter-wave plate (26), and a first beam splitter (13). The half-wave plate (22) is used to control the polarization direction of the illumination beam; when the adaptive module (19) performs wavefront optimization on the illumination beam, the illumination beam whose polarization direction is changed by the half-wave plate (22) illuminates the polarization beam splitter (23). The polarizing beam splitter (23) works in conjunction with the half-wave plate (22). The polarizing beam splitter (23) is used to split the illumination beam into transmitted light and reflected light. The transmitted light continues to be transmitted as the illumination beam to the quarter-wave plate (26) for wavefront optimization. The quarter-wave plate (26) is used to rotate the polarization direction of the transmitted light and to incident the transmitted light, which is the illumination beam, onto the deformable mirror (27). The deformable mirror (27) is used to reflect the illumination beam that has passed through the quarter-wave plate (26). The reflected illumination beam passes through the quarter-wave plate (26) again to change its polarization direction and then enters the first beam splitter (13). The first beam splitter (13) is used to split the illumination beam reflected by the deformable mirror (27). The illumination beam is transmitted through the first beam splitter (13) to the mask (17) for exposure illumination. The illumination beam is reflected through the first beam splitter (13) to the wavefront sensor (28) to detect the wavefront data.

14. The exposure detection and control system for optimizing the wavefront of an illumination beam according to claim 13, characterized in that, The primary mirror of the deformable mirror (27) is a silver-coated reflector; the interior of the deformable mirror (27) has a variable support column, and the deformation of the deformable mirror (27) can be achieved by extending or retracting the variable support column, thereby physically modulating the illumination beam incident on the deformable mirror (27); and / or, The wavefront sensor (28) detects the wavefront information of the incident light and outputs the corresponding RMS wavefront value and PV value to the control software. The control software optimizes the variable strut extension of the deformable mirror (27) through optimization calculation, optimizes the RMS wavefront value, and keeps the RMS wavefront value stable.

15. A holographic exposure system, characterized in that, include: An exposure detection system for adjusting the orientation of a photomask, as described in any one of claims 1 to 9; The exposure detection system for detecting the state of an illumination beam as described in claim 10 or 11; The exposure detection and control system for wavefront optimization of illumination beams according to any one of claims 12 to 14; and, Mask (17) and illumination source (29).

16. The holographic exposure system according to claim 15, characterized in that, Also includes: Optical switch (30), half-wave plate (22), motorized mirror assembly (31), beam expander (32), variable aperture stop (33) and homogenizer (34); The illumination beam emitted by the illumination source (29) passes sequentially through the light switch (30), the half-wave plate (22), and the electric reflector group (31), and then enters the homogenizing mirror (34) through the variable aperture stop (33). The homogenized illumination beam then enters the exposure detection and control system.

17. A method for detecting incident light in a holographic exposure system, characterized in that, include: The deformable mirror (27) detection includes the following steps: by removing the deformable mirror (27) from the optical path of the holographic exposure system, the clarity of the diffraction image of the mask (17) before and after removing the deformable mirror (27) is compared to determine whether the deformable mirror (27) is damaged; The calibration of the autocollimation module (1) includes the following steps: using the indicator light (2) to return to the autocollimation camera (5) via the optical element; by adjusting the position of the autocollimation camera (5), the indicator light (2) hits the center position of the autocollimation camera (5), and the accurate calibration of the autocollimation module (1) is completed. Wavefront optimization of the illumination beam of the mask includes the following steps: the illumination beam is incident on the deformable mirror (27) through an optical element; the deformable mirror (27) reflects the illumination beam, which is then reflected again by the optical element, and the reflected light is reflected into the wavefront sensor (28) through the first beam splitter (13); the wavefront sensor (28) detects wavefront data and feeds it back to the deformable mirror (27), and the deformable mirror (27) modulates the beam accordingly to optimize the wavefront of the illumination beam of the mask (17); The indicator light (2) and the illumination beam are combined by the following steps: the indicator light (2) is incident on the first beam splitter (13) through the mirror group (12), and the position of the second positioning hole (15) and / or the position of the mirror group (12) are adjusted so that the indicator light (2) and the illumination beam are combined. The illumination beam state detection includes the following steps: a portion of the monitoring light is drawn out from the illumination beam through a polarizing beam splitter (23), and after beam splitting and focusing, it is sent to a power meter (20) and a position monitoring camera (21) respectively, so as to realize real-time monitoring of the power and beam directionality of the illumination beam.

18. The incident light detection method for the holographic exposure system according to claim 17, characterized in that, The incident light detection method is applied to the holographic exposure system described in claim 15 or 16.

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