Interference exposure system, method and grating exposure system

Abstract

The present application discloses an interference exposure system, method and grating exposure system, which relate to the field of optics. The interference exposure system comprises: a coherent light source module, which is used to output a first coherent light beam and a second coherent light beam, wherein the beam angle between the first coherent light beam and the second coherent light beam is a first angle; a beam adjustment module, which adjusts the optical path of the first coherent light beam to obtain a third coherent light beam, and adjusts the optical path of the second coherent light beam to obtain a fourth coherent light beam, wherein the beam angle between the third coherent light beam and the fourth coherent light beam is a second angle, and the second angle is smaller than the first angle; a period measurement module, which is used to detect the fringe period of interference fringes formed by the third coherent light beam and the fourth coherent light beam; and a control module, which is used to determine corresponding adjustment parameters according to the fringe period, and adjust the beam adjustment module according to the adjustment parameters, so that the fringe period of interference fringes formed by the third coherent light beam and the fourth coherent light beam meets a preset period accuracy.

Description

Technical Field

[0001] The present application relates to the field of optical technology, and more specifically, to an interference exposure system, method and grating exposure system. Background Art

[0002] AR hardware display systems usually consist of two parts: a micro-optical engine and an optical combiner. Among these two parts, the waveguide is a very important component. It can be used as a device for lighting in the micro-optical engine, and it can also be used as a device for introducing the optical engine image into the human eye in the optical combiner. The current mainstream waveguide coupling-in and coupling-out schemes include arrayed optical waveguides, surface relief gratings, and volume holographic gratings. Interference exposure is one of the important means to prepare surface relief gratings and volume holographic gratings.

[0003] However, in the process of using the interference exposure process to prepare waveguides by Mr. Zhang in related technology, the preparation accuracy of the interference exposure samples still needs to be improved; in addition, due to the different performance requirements of waveguides used in different optomechanics and optical combiners, the preparation of waveguides with different grating periods is involved, which also puts higher requirements on the flexibility of the interference exposure system. Summary of the invention

[0004] In view of the above problems, the present application proposes an interference exposure system, method and grating exposure system.

[0005] In a first aspect, an embodiment of the present application provides an interference exposure system, which includes: a coherent light source module, used to output a first coherent light beam and a second coherent light beam, the beam angle between the first coherent light beam and the second coherent light beam being a first angle; a beam adjustment module, located on the optical path of the first coherent light beam and the second coherent light beam, the beam adjustment module being used to adjust the optical path of the first coherent light beam to obtain a third coherent light beam, and to adjust the optical path of the second coherent light beam to obtain a fourth coherent light beam, the beam angle between the third coherent light beam and the fourth coherent light beam being a second angle, and the second angle being smaller than the first angle; a period measurement module, used to detect a fringe period of interference fringes formed by the third coherent light beam and the fourth coherent light beam; and a control module, used to determine corresponding adjustment parameters according to the fringe period, and adjust the beam adjustment module according to the adjustment parameters so that the fringe period of the interference fringes formed by the third coherent light beam and the fourth coherent light beam meets a preset period accuracy.

[0006] In a second aspect, an embodiment of the present application further provides an interference exposure method, which is applied to the aforementioned interference exposure system, and the method includes: outputting a first coherent light beam and a second coherent light beam through the coherent light source module, and the beam angle between the first coherent light beam and the second coherent light beam is a first angle; adjusting the optical path of the first coherent light beam through the beam adjustment module to obtain a third coherent light beam, and adjusting the optical path of the second coherent light beam to obtain a fourth coherent light beam, and the beam angle between the third coherent light beam and the fourth coherent light beam is a second angle, and the second angle is smaller than the first angle; detecting the fringe period of the interference fringes formed by the third coherent light beam and the fourth coherent light beam through the period measurement module; determining corresponding adjustment parameters according to the fringe period through the control module, and adjusting the beam adjustment module according to the adjustment parameters, so that the fringe period of the interference fringes formed by the third coherent light beam and the fourth coherent light beam meets the preset period accuracy.

[0007] In a third aspect, an embodiment of the present application provides a grating exposure system, comprising a substrate to be prepared into a grating structure and an interference exposure system as described in any one of claims 1 to 9, wherein the substrate is arranged at a target position of a base, and the target position is located on the optical path of the third coherent light beam and the fourth coherent light beam output by the adjusted beam adjustment module, so that the third coherent light beam and the fourth coherent light beam form interference fringes on the substrate whose fringing period satisfies the preset period accuracy.

[0008] The interference exposure system provided by the present application is characterized in that a coherent light source module outputs a first coherent light beam and a second coherent light beam, and the beam angle between the first coherent light beam and the second coherent light beam is a first angle; a beam adjustment module adjusts the optical path of the first coherent light beam to obtain a third coherent light beam, and adjusts the optical path of the second coherent light beam to obtain a fourth coherent light beam, and the beam angle between the third coherent light beam and the fourth coherent light beam is a second angle, and the second angle is smaller than the first angle; a period measurement module detects the fringe period of the interference fringes formed by the third coherent light beam and the fourth coherent light beam; a control module determines corresponding adjustment parameters according to the fringe period, and adjusts the beam adjustment module according to the adjustment parameters, so that the fringe period of the interference fringes formed by the third coherent light beam and the fourth coherent light beam meets the preset period accuracy. In this way, the preparation of grating structures with different periods can be realized, and the preparation accuracy of the waveguide is improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0009] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For those skilled in the art, other drawings can be obtained based on these drawings without creative work.

[0010] Figure 1 A system architecture diagram of an interference exposure system provided by an embodiment of the present application is shown;

[0011] Figure 2 A system architecture diagram of an interference exposure system provided by another embodiment of the present application is shown;

[0012] Figure 3 A schematic diagram of fringe period measurement provided by an embodiment of the present application is shown;

[0013] Figure 4 A system architecture diagram of an interference exposure system provided by another embodiment of the present application is shown;

[0014] Figure 5 A schematic flow chart of an interference exposure method provided in one embodiment of the present application is shown. DETAILED DESCRIPTION

[0015] In order to enable those skilled in the art to better understand the solution of the present application, the technical solution in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application.

[0016] In the description of the present invention, the terms "first", "second", etc. are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of the features. In the description of the present invention, the meaning of "plurality" is two or more, unless otherwise clearly and specifically defined.

[0017] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection, an electrical connection, or mutual communication; it can be a direct connection, or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0018] The embodiments of the present application provide an interference exposure system and method, which can improve the accuracy and stability of interference exposure, and also allow the exposure cycle to be adjusted arbitrarily.

[0019] See also Figure 1 , Figure 1 1 is a schematic diagram of the system architecture of an interference exposure system 10 provided in an embodiment of the present application. The interference exposure system 10 includes: a coherent light source module 110 , a beam adjustment module 120 , a period measurement module 130 and a control module 140 .

[0020] In this embodiment, the coherent light source module 110 is used to output a first coherent light beam and a second coherent light beam, and the beam angle between the first coherent light beam and the second coherent light beam is a first angle. The first coherent light beam and the second coherent light beam can generate an interference exposure field, that is, interference fringes can be formed. Among them, the period T of the interference fringes and the beam angle θ between the first coherent light beam and the second coherent light beam can be expressed by the following function:

[0021] T=λ / 2sinθ

[0022] Where λ is the wavelength of the coherent light beam. The period of the interference fringes is negatively correlated with the beam angle θ, that is, the smaller the beam angle θ, the larger the period of the interference fringes; the larger the beam angle θ, the smaller the period of the interference fringes. The smaller the period of the interference fringes, the denser the interference fringes on the interference exposure field; the larger the period of the interference fringes, the sparser the interference fringes on the interference exposure field.

[0023] Since the beam angle between the first coherent light beam and the second coherent light beam output by the coherent light source module is relatively large, the fringe period of the formed interference fringes will be relatively small, and the interference fringes will be too dense, which may affect the detection accuracy of the interference fringe period, making it impossible to accurately adjust the fringe period of the generated interference fringes to the required preset period accuracy.

[0024] Based on this, the beam adjustment module 120 in the present application can be set on the optical path of the first coherent light beam and the second coherent light beam. The beam adjustment module is used to adjust the optical path of the first coherent light beam to obtain the third coherent light beam, and adjust the optical path of the second coherent light beam to obtain the fourth coherent light beam. The beam angle between the third coherent light beam and the fourth coherent light beam is a second angle, and the second angle is smaller than the first angle. In other words, since the angle between the first coherent light beam and the second coherent light beam output by the coherent light source module 110 is relatively large, the beam adjustment module 120 can be used to draw out the first coherent light beam and the second coherent light beam, that is, to change the propagation direction of the first coherent light beam and the second coherent light beam, so that the beam angle between the first coherent light beam after the propagation direction is changed and the second coherent light beam after the propagation direction is changed becomes smaller. Thereby, the fringe period of the interference fringes in the interference exposure field formed by the third coherent light beam and the fourth coherent light beam becomes larger, that is, the interference fringes in the interference exposure field formed by the third coherent light beam and the fourth coherent light beam become sparse, which helps to accurately measure the fringe period of the interference fringes, and further helps to more accurately adjust the fringe period of the interference fringes obtained by the interference exposure to a preset period accuracy.

[0025] Furthermore, the period measurement module 130 detects the period of interference fringes formed by the third coherent light beam and the fourth coherent light beam.

[0026] The control module 140 determines corresponding adjustment parameters according to the fringe period, and adjusts the beam adjustment module 120 according to the adjustment parameters so that the fringe period of the interference fringes formed by the third coherent light beam and the fourth coherent light beam meets a preset period accuracy.

[0027] For example, if the period accuracy of the fringe period of the detected interference fringes is greater than the preset period accuracy, the control module 140 can determine the corresponding first adjustment parameter and adjust the beam adjustment module 120 according to the first adjustment parameter, thereby reducing the fringe period of the interference fringes formed by the third coherent light beam and the fourth coherent light beam.

[0028] For another example, if the control module 140 detects that the period accuracy of the fringe period of the interference fringes is less than the preset period accuracy, it can determine the corresponding second adjustment parameter and adjust the beam adjustment module 120 according to the second adjustment parameter, thereby increasing the fringe period of the interference fringes formed by the third coherent light beam and the fourth coherent light beam.

[0029] Optionally, the control module 140 may detect the fringe period of the interference fringes in real time, and adjust the beam adjustment module 120 multiple times until the fringe period of the interference fringes formed by the third coherent light beam and the fourth coherent light beam meets a preset period accuracy.

[0030] In some embodiments, the preset period accuracy is set based on the stripe period accuracy required for the grating structure to be prepared. Therefore, after the stripe period of the interference stripes formed by the third coherent light beam and the fourth coherent light beam meets the preset period accuracy, the substrate to be prepared as the grating structure can be placed at a target position on the base, and the target is located on the optical path of the third coherent light beam and the fourth coherent light beam output by the adjusted beam adjustment module, so that the third coherent light beam and the fourth coherent light beam form interference stripes on the substrate with a stripe period that meets the preset period accuracy.

[0031] Among them, the surface of the substrate is generally coated with a photosensitive material, and the photosensitive material can be a positive photoresist. After multiple interference exposures, the positive photoresist on the surface of the substrate can be cleaned by a developer, and the exposed part is dissolved, and the unexposed part is left, so that the surface of the substrate forms an image of a grating structure. Of course, the photosensitive material can also be a negative photoresist. After multiple interference exposures, the positive photoresist on the surface of the substrate can be cleaned by a developer, and the unexposed part is dissolved, and the exposed part is left, so that the surface of the substrate can also form an image of a micro-nano grating structure.

[0032] In this embodiment, after the two coherent light beams outputted by the coherent light source are respectively extracted by the beam adjustment unit, the fringe period of the interference fringes formed by the two coherent light beams extracted is recorded. Since the angle between the extracted light beams is much smaller than the angle between the light beams in the interference exposure field, the fringe period of the interference fringes formed in the interference exposure field becomes larger, that is, the interference fringes in the interference exposure field formed by the third coherent light beam and the fourth coherent light beam become sparse, which helps to accurately measure the fringe period of the interference fringes. In other words, the interference fringe period recorded by the period measurement module can reach the millimeter level, which ensures the accuracy of the period measurement, and further helps to more accurately adjust the fringe period of the interference fringes obtained by the interference exposure to the preset period accuracy. In addition, the beam angle of the two coherent light beams outputted by the coherent light source can be arbitrarily adjusted by the beam adjustment module, so as to realize a high-precision and flexible period-adjustable interference exposure system, that is, it can be used to prepare grating structures with high period accuracy of different periods.

[0033] See also Figure 2 , Figure 2 1 is a schematic diagram of the structure of an interference exposure system 10 provided in another embodiment of the present application. The interference exposure system 10 comprises: a coherent light source module 110 , a beam adjustment module 120 , a period measurement module 130 and a control module 140 .

[0034] In this embodiment, the beam adjustment module 120 may include a first beam splitter 121 , a first reflector 122 , and a second reflector 123 .

[0035] Among them, the first beam splitter 121 is located on the optical path of the first coherent light beam and the second coherent light beam, and the first beam splitter 121 is used to split the first coherent light beam and the second coherent light beam; the first reflector 122 is located on the optical path of the first coherent light beam after the beam splitting process, and adjusts the optical path of the first coherent light beam after the beam splitting process to obtain a third coherent light beam; the second reflector 123 is located on the optical path of the second coherent light beam after the beam splitting process, and adjusts the optical path of the second coherent light beam after the beam splitting process to obtain a fourth coherent light beam.

[0036] Optionally, the first beam splitter 121 may be Figure 2 The first reflector 122 and the second reflector 123 move up and down in the vertical direction in the plane shown in FIG. Figure 2 It can also be rotated or moved arbitrarily within the plane shown.

[0037] In this embodiment, the period measurement module 130 may include an interference exposure component 131 , a base 132 , an image acquisition unit 133 , and a processing unit 134 .

[0038] The interference exposure component 131 is disposed on the base, and is located on the optical paths of the third coherent light beam and the fourth coherent light beam, and the third coherent light beam and the fourth coherent light beam form interference fringes through the interference exposure component 131. The interference exposure component 131 may be a beam splitter, and the third coherent light beam and the fourth coherent light beam may be projected and refracted on the surface of the beam splitter, thereby forming interference fringes.

[0039] The image acquisition unit 133 is used to acquire the first fringe image of the interference fringe. The image acquisition unit 133 may be a CCD camera (charge coupled device camera), or other sensors capable of acquiring interference fringe images, which is not limited in this embodiment.

[0040] The base 132 can be displaced by electric control, thereby driving the interference exposure component 131 to move the target distance, and the target distance is a preset multiple of the empirical value of the fringe period of the interference fringes formed by the first coherent light beam and the second coherent light beam. Since the fringe period of the interference fringes is generally in the micrometer or hundred nanometer level, when the target distance is small, the number of fringe periods measured is small, and the target distance is almost impossible to be exactly an integer multiple of the fringe period of the interference fringes. When calculating the fringe period, it is necessary to divide by the estimated decimal place, so the error measured when the target distance is small is large. That is, the larger the target distance, the more accurate the calculated fringe period. However, if the target distance is too large, the base movement distance is too large, and the number of interference fringes that need to be counted is also too large. Therefore, the target distance can be a preset multiple of the fringe period of the interference fringes. The preset multiple can be set to any multiple between 10 times and 10,000 times according to the empirical value. The specific multiple value used can be determined according to actual needs, and this embodiment does not limit this. For example, the actual period of the fringe period of the aforementioned interference fringe is 405.12 nanometers (Nanometer, nm), and its actual period can be estimated in advance to be between 404nm and 406nm; based on this, 406nm can be used as the empirical value of the fringe period of the aforementioned interference fringe, and the preset multiple can be 1000. The base 132 is displaced by electric control to drive the interference exposure component 131 to move 406000nm. In this way, the moving target distance is exactly an integer multiple of the empirical value of the interference fringe period, so as to solve the fringe period in the subsequent solution, and avoid the problem of excessive error in the final solved fringe period due to the need to divide by the estimated decimal place when solving the fringe period.

[0041] It can be understood that the interference exposure assembly 131 moves along with the movement of the base 132, thereby causing the optical path between the third coherent light beam and the fourth coherent light beam to change, that is, causing the movement of the interference fringes. Therefore, the image acquisition unit 133 can further acquire a second fringe image of the interference fringes formed by the interference exposure assembly 131 after the movement of the third coherent light beam and the fourth coherent light beam. Figure 2 As shown, the solid line stripes can be regarded as the first stripe image, and the dotted line stripes can be regarded as the second stripe image. Further, the image acquisition unit 133 transmits the acquired first stripe image and the second stripe image to the processing unit 134.

[0042] Further, the processing unit 134 can determine the fringe period of the interference fringes according to the first fringe image, the second fringe image and the target distance of the interference fringes. Figure 3 , the formula for calculating the fringe period can be expressed by the following function:

[0043] Λ=D / N

[0044] Wherein, Λ represents the distance that the interference exposure component 131 needs to move when the interference fringe moves one fringe cycle, D represents the moving distance of the interference exposure component 131, and N represents the number of cycles of the interference fringe movement.

[0045] Based on this, after determining the fringe period of the interference fringe through the above-mentioned function for calculating the fringe period, the calculated fringe period can be further sent to the control module 140. The control module 140 determines the corresponding adjustment parameters according to the fringe period, and adjusts the beam adjustment module according to the adjustment parameters.

[0046] Optionally, the adjustment parameters may include a first angle adjustment parameter and a second angle adjustment parameter, and the control module 140 is used to adjust the placement angle of the first reflector 122 according to the first angle adjustment parameter, and adjust the placement angle of the second reflector 123 according to the second angle adjustment parameter.

[0047] Exemplarily, if the beam angle needs to be reduced by 4θ, the control module 140 can control the first reflector 122 to rotate clockwise by θ according to the first angle adjustment parameter, and control the second reflector 123 to rotate counterclockwise by θ according to the second angle adjustment parameter, thereby reducing the beam angle between the third coherent beam and the fourth coherent beam by 4θ.

[0048] Optionally, the adjustment parameters include a first angle adjustment parameter, a second angle adjustment parameter, and a first posture adjustment parameter, and the control module is used to adjust the placement angle of the first reflector 122 according to the first angle adjustment parameter, adjust the placement angle of the second reflector 123 according to the second angle adjustment parameter, and adjust the placement angle and / or placement position of the first beam splitter 121 according to the first posture adjustment parameter. In this way, the placement angle and / or placement position of the first beam splitter 121, the first reflector 122, and the second reflector 123 can be controlled to be adjusted at the same time, so that the beam angle changes with a higher degree of freedom, that is, a higher degree of freedom and more diverse angle adjustment methods are provided.

[0049] Optionally, the adjustment parameters include a second posture adjustment parameter, a third posture adjustment parameter and a first posture adjustment parameter, and the control module is used to adjust the placement angle and / or placement position of the first reflector 122 according to the second posture adjustment parameter, adjust the placement angle and / or placement position of the second reflector 123 according to the third posture adjustment parameter, and adjust the placement angle and / or placement position of the first beam splitter 121 according to the first posture adjustment parameter.

[0050] Furthermore, the same method as above can be used to detect the fringe period of the interference fringes formed by the third coherent light beam and the fourth coherent light beam output by the adjusted light beam adjustment module. If the preset period accuracy is not met, the corresponding adjustment parameters can be continuously generated, and the placement position and / or placement angle of the optical elements in the light beam adjustment module can be continuously adjusted until interference fringes that meet the preset period accuracy are obtained. The preset period accuracy can be 1 nanometer, if the required fringe period of the interference fringes is 500 nanometers. The fringe period of the interference fringes obtained after adjustment is between 499 nanometers and 501 nanometers, which is considered to meet the preset period accuracy.

[0051] Optionally, if the preset period accuracy is met, the placement positions and placement angles of the first beam splitter 121, the first reflector 122, and the second reflector 123 are fixed, and Figure 2 The substrate is moved to the position of the interference exposure assembly 131 for interference exposure. The position of the substrate can be moved manually or automatically by electronic control. The position of the substrate can also be roughly adjusted manually, that is, the substrate is moved to the desired approximate position, and then the position of the substrate is finely adjusted by electronic control, so that the substrate is automatically moved to a precise position within a small range to achieve accurate interference exposure.

[0052] That is to say, the grating exposure system may include a substrate to be prepared into a grating structure and the interference exposure system 10 provided in this embodiment, and the substrate is set on a target position of a base, and the target position is located on the optical path of the third coherent light beam and the fourth coherent light beam output by the adjusted beam adjustment module, so that the third coherent light beam and the fourth coherent light beam form interference fringes on the substrate whose fringing period meets the preset period accuracy.

[0053] In this embodiment, after the two coherent light beams outputted by the coherent light source composed of the first beam splitter 121, the first reflector 122 and the second reflector 123 are respectively extracted, the fringe period of the interference fringes formed by the two coherent light beams after extraction is recorded. Since the angle between the extracted light beams is much smaller than the angle of the light beams in the interference exposure field, the fringe period of the interference fringes formed in the interference exposure field becomes larger, that is, the interference fringes in the interference exposure field formed by the third coherent light beam and the fourth coherent light beam become sparse, which helps to accurately measure the fringe period of the interference fringes. In other words, the interference fringe period recorded by the period measurement module can reach the millimeter level, ensuring the accuracy of the period measurement, and further helping to more accurately adjust the fringe period of the interference fringes obtained by the interference exposure to the preset period accuracy. In addition, the beam angle of the two coherent light beams outputted by the coherent light source can be arbitrarily adjusted through the beam adjustment module, so as to realize a high-precision and flexible period-adjustable interference exposure system, that is, it can be used to prepare grating structures with high period accuracy of different periods.

[0054] See also Figure 4 , Figure 4 1 is a schematic diagram of the structure of an interference exposure system 10 provided in another embodiment of the present application. The interference exposure system 10 includes: a coherent light source module 110, a beam adjustment module 120, a period measurement module 130 and a control module 140. The beam adjustment module 120 may include a first displacement prism 124, a second displacement prism 125 and a convex lens 126; the period measurement module 130 includes an interference exposure component 131, a base 132, an image acquisition unit 133 and a processing unit 134.

[0055] In this embodiment, the beam adjustment module 120 may include a first displacement prism 124, a second displacement prism 125, and a convex lens 126; the first displacement prism 124 is located on the optical path of the first coherent light beam, and the first displacement prism 124 is used to adjust the beam width of the first coherent light beam; the second displacement prism 125 is located on the optical path of the second coherent light beam, and the second displacement prism 125 is used to adjust the beam width of the second coherent light beam. Optionally, both the first displacement prism 124 and the second displacement prism 125 can be replaced by a beam expander, which is not shown in this embodiment.

[0056] The convex lens 126 is located on the optical paths of the adjusted first coherent light beam and the second coherent light beam, and is used to adjust the optical path of the adjusted first coherent light beam to obtain the third coherent light beam, and to adjust the optical path of the adjusted second coherent light beam to obtain the fourth coherent light beam. In addition, the third coherent light beam and the fourth coherent light beam emitted by the convex lens 126 will converge on the interference exposure assembly 131.

[0057] The first displacement prism 124 and the second displacement prism 125 can be Figure 4 The convex lens 126 can be rotated arbitrarily within the plane shown in FIG. 1 , that is, the placement angles of the first displacement prism 124 and the second displacement prism 125 can be adjusted; Figure 4 The plane shown moves up and down in the vertical direction.

[0058] Optionally, the interference exposure component 131 may be a diffraction grating, which is used to reflect and transmit the third coherent light beam incident from the first side and the fourth coherent light beam incident from the second side, so that the transmitted light beam and the reflected light beam of the same diffraction order of the third coherent light beam and the fourth coherent light beam form the interference fringes. The direction of the grating period of the diffraction grating is located on the angular bisector of the beam angle formed by the third coherent light beam and the fourth coherent light beam.

[0059] Further, the image acquisition unit 133 can acquire a first fringe image of interference fringes formed by the third coherent light beam and the fourth coherent light beam. The image acquisition unit 133 can be a CCD camera, or other sensors capable of acquiring interference fringe images, which is not limited in this embodiment.

[0060] The base 132 can be displaced by electric control, thereby driving the interference exposure component 131 to move the target distance, and the target distance is a preset multiple of the empirical value of the fringe period of the interference fringes formed by the first coherent light beam and the second coherent light beam. Since the fringe period of the interference fringes is generally in the micrometer or hundred nanometer level. When the target distance is small, the measured fringe period is small, and the target distance is almost impossible to be an integer multiple of the fringe period of the interference fringes. When calculating the fringe period, it is necessary to divide by the estimated decimal place, so the error measured when the target distance is small is large. That is, the larger the target distance, the more accurate the calculated fringe period. However, if the target distance is too large, the base movement distance is too large, and the number of interference fringes that need to be counted is too large. Therefore, the target distance can be a preset multiple of the empirical value of the fringe period of the interference fringes. The preset multiple can be set at any multiple between 10 times and 10,000 times according to the empirical value. The specific multiple value used can be determined according to actual needs, and this embodiment does not limit this. For example, the actual period of the fringe period of the aforementioned interference fringe is 405.12 nanometers (Nanometer, nm), and its actual period can be estimated in advance to be between 404nm and 406nm; based on this, 406nm can be used as the empirical value of the fringe period of the aforementioned interference fringe, and the preset multiple can be 1000. The base 132 is displaced by electric control to drive the interference exposure component 131 to move 406000nm. In this way, the moving target distance is exactly an integer multiple of the empirical value of the interference fringe period, so as to solve the fringe period in the subsequent solution, and avoid the problem of excessive error in the final solved fringe period due to the need to divide by the estimated decimal place when solving the fringe period.

[0061] It can be understood that the interference exposure assembly 131 moves along with the movement of the base 132, thereby causing the optical path between the third coherent light beam and the fourth coherent light beam to change, that is, causing the movement of the interference fringes. Therefore, the image acquisition unit 133 can further acquire a second fringe image of the interference fringes formed by the interference exposure assembly 131 after the movement of the third coherent light beam and the fourth coherent light beam. Figure 2 As shown, the solid line stripes can be regarded as the first stripe image, and the dotted line stripes can be regarded as the second stripe image. Further, the image acquisition unit 133 transmits the acquired first stripe image and the second stripe image to the processing unit 134.

[0062] Further, the processing unit 134 can determine the fringe period of the interference fringes according to the first fringe image, the second fringe image and the target distance of the interference fringes. Figure 3 , the formula for calculating the stripe period can still be expressed by the following function:

[0063] Λ=D / N

[0064] Wherein, Λ represents the distance that the interference exposure component 131 needs to move when the interference fringe moves one fringe cycle, D represents the moving distance of the interference exposure component 131, and N represents the number of cycles of the interference fringe movement.

[0065] Based on this, after the fringe period of the interference fringe is determined by the function of solving the fringe period, the calculated fringe period can be further sent to the control module 140. The control module 140 determines the corresponding adjustment parameters according to the fringe period, and adjusts the beam adjustment module according to the adjustment parameters. In this embodiment, after the third coherent light beam and the fourth coherent light beam at different distances are incident on the convex lens, it is equivalent to the convex lens focusing on spots of different sizes. The larger the spot size, the larger the beam angle after focusing, and the maximum angle depends on the numerical aperture of the lens.

[0066] Based on this, the adjustment parameters may include a first rotation parameter, a second rotation parameter, and a first displacement parameter. At this time, the control module 140 may adjust the placement angle of the first displacement prism 124 according to the first rotation parameter, adjust the second displacement prism 125 according to the second rotation parameter, and move the convex lens 126 in the vertical direction according to the first displacement parameter, so that the two light beams output by the first displacement prism 124 and the second displacement prism 125 can converge at a suitable position on the interference exposure assembly 131 after passing through the convex lens 126.

[0067] For example, if the beam angle between the third coherent light beam and the fourth coherent light beam needs to be reduced, the control module 140 can control the first displacement prism 124 to rotate clockwise by θ according to the first rotation parameter, control the second displacement prism 125 to rotate counterclockwise by θ according to the second rotation parameter, and control the convex lens 126 to rotate counterclockwise by θ according to the first displacement parameter. Figure 4 The plane shown is moved downward by a specified distance in the vertical direction, so that the angle between the third coherent light beam and the fourth coherent light beam passing through the convex lens 126 can be reduced.

[0068] Optionally, the adjustment parameters include a fourth posture adjustment parameter, a fifth posture adjustment parameter, and a sixth posture adjustment parameter. The control module 140 adjusts the placement angle and / or placement position of the first displacement prism 124 according to the fourth posture adjustment parameter, adjusts the placement angle and / or placement position of the second displacement prism 125 according to the fifth posture adjustment parameter, and adjusts the placement angle and / or placement position of the convex lens 126 according to the sixth posture adjustment parameter. In this way, a more flexible and diverse angle adjustment method is provided.

[0069] Furthermore, the same method as mentioned above can be used to detect the fringe period of the interference fringes formed by the third coherent light beam and the fourth coherent light beam output by the adjusted light beam adjustment module. If the preset period accuracy is not met, the corresponding adjustment parameters can be continuously generated, and the placement position and / or placement angle of the optical elements in the light beam adjustment module can be continuously adjusted until interference fringes that meet the preset period accuracy are obtained.

[0070] Optionally, if the preset period accuracy is met, the placement positions and placement angles of the first displacement prism 124, the second displacement prism 125 and the convex lens 126 are fixed, and Figure 4 The substrate is moved to the position of the interference exposure assembly 131 for interference exposure. The position of the substrate can be moved manually or automatically by electronic control. The position of the substrate can also be roughly adjusted manually, that is, the substrate is moved to the desired approximate position, and then the position of the substrate is finely adjusted by electronic control, so that the substrate is automatically moved to a precise position within a small range to achieve accurate interference exposure.

[0071] That is to say, the grating exposure system may include a substrate to be prepared into a grating structure and the interference exposure system 10 provided in this embodiment, and the substrate is set on a target position of a base, and the target position is located on the optical path of the third coherent light beam and the fourth coherent light beam output by the adjusted beam adjustment module, so that the third coherent light beam and the fourth coherent light beam form interference fringes on the substrate whose fringing period meets the preset period accuracy.

[0072] In this embodiment, after the two coherent light beams outputted by the coherent light source composed of the first displacement prism 124, the second displacement prism 125 and the convex lens 126 are respectively extracted, the fringe period of the interference fringes formed by the two coherent light beams after extraction is recorded. Since the angle between the extracted light beams is much smaller than the angle of the light beams in the interference exposure field, the fringe period of the interference fringes formed in the interference exposure field becomes larger, that is, the interference fringes in the interference exposure field formed by the third coherent light beam and the fourth coherent light beam become sparse, which helps to accurately measure the fringe period of the interference fringes. In other words, the interference fringe period recorded by the period measurement module can reach the millimeter level, ensuring the accuracy of the period measurement, and then helping to more accurately adjust the fringe period of the interference fringes obtained by the interference exposure to the preset period accuracy. In addition, the beam angle of the two coherent light beams outputted by the coherent light source can be arbitrarily adjusted through the beam adjustment module, so as to realize a high-precision and flexible period-adjustable interference exposure system, that is, it can be used to prepare grating structures with high period accuracy of different periods.

[0073] See also Figure 5 , Figure 5 1 is a flow chart of an interference exposure method provided by an embodiment of the present application, which is applied to the interference exposure system mentioned in any of the above embodiments. Figure 5 The interference exposure method provided in the embodiment of the present application is described in detail. The interference exposure method may include the following steps:

[0074] Step S510: outputting a first coherent light beam and a second coherent light beam through the coherent light source module, wherein a beam angle between the first coherent light beam and the second coherent light beam is a first angle.

[0075] Step S520: adjusting the optical path of the first coherent light beam through the beam adjustment module to obtain a third coherent light beam, and adjusting the optical path of the second coherent light beam to obtain a fourth coherent light beam, wherein the beam angle between the third coherent light beam and the fourth coherent light beam is a second angle, and the second angle is smaller than the first angle.

[0076] Step S530: Detecting the fringe period of interference fringes formed by the third coherent light beam and the fourth coherent light beam by the period measurement module.

[0077] Step S540: determining corresponding adjustment parameters according to the fringe period by the control module, and adjusting the beam adjustment module according to the adjustment parameters so that the fringe period of the interference fringes formed by the third coherent beam and the fourth coherent beam meets the preset period accuracy.

[0078] In this embodiment, the specific implementation of steps S510 to S540 can refer to the contents of the aforementioned embodiments, which will not be described in detail here.

[0079] In this embodiment, after the two coherent light beams outputted by the coherent light source are respectively extracted by the beam adjustment unit, the fringe period of the interference fringes formed by the two coherent light beams extracted is recorded. Since the angle between the extracted light beams is much smaller than the angle between the light beams in the interference exposure field, the fringe period of the interference fringes formed in the interference exposure field becomes larger, that is, the interference fringes in the interference exposure field formed by the third coherent light beam and the fourth coherent light beam become sparse, which helps to accurately measure the fringe period of the interference fringes. In other words, the interference fringe period recorded by the period measurement module can reach the millimeter level, which ensures the accuracy of the period measurement, and further helps to more accurately adjust the fringe period of the interference fringes obtained by the interference exposure to the preset period accuracy. In addition, the beam angle of the two coherent light beams outputted by the coherent light source can be arbitrarily adjusted by the beam adjustment module, so as to realize a high-precision and flexible period-adjustable interference exposure system, that is, it can be used to prepare grating structures with high period accuracy of different periods.

Claims

1. An interference exposure system, characterized in that: The interference exposure system comprises: A coherent light source module, configured to output a first coherent light beam and a second coherent light beam, wherein a beam angle between the first coherent light beam and the second coherent light beam is a first angle; a beam adjustment module, located on the optical paths of the first coherent beam and the second coherent beam, the beam adjustment module being used to adjust the optical path of the first coherent beam to obtain a third coherent beam, and to adjust the optical path of the second coherent beam to obtain a fourth coherent beam, wherein a beam angle between the third coherent beam and the fourth coherent beam is a second angle, and the second angle is smaller than the first angle; A period measurement module, used for detecting the period of interference fringes formed by the third coherent light beam and the fourth coherent light beam; A control module is used to determine corresponding adjustment parameters according to the fringe period, and adjust the beam adjustment module according to the adjustment parameters so that the fringe period of the interference fringes formed by the third coherent light beam and the fourth coherent light beam meets a preset period accuracy.

2. The interference exposure system according to claim 1, characterized in that: The beam adjustment module includes: a first beam splitter, a first reflector and a second reflector; The first beam splitter is located on the optical paths of the first coherent light beam and the second coherent light beam, and the first beam splitter is used to perform beam splitting processing on the first coherent light beam and the second coherent light beam; The first reflector is located on the optical path of the first coherent light beam after the beam splitting process, and adjusts the optical path of the first coherent light beam after the beam splitting process to obtain the third coherent light beam; The second reflector is located on the optical path of the second coherent light beam after the beam splitting process, and adjusts the optical path of the second coherent light beam after the beam splitting process to obtain the fourth coherent light beam.

3. The interference exposure system according to claim 2, characterized in that: The adjustment parameters include a first angle adjustment parameter and a second angle adjustment parameter, and the control module is used to adjust the placement angle of the first reflector according to the first angle adjustment parameter, and to adjust the placement angle of the second reflector according to the second angle adjustment parameter.

4. The interference exposure system according to claim 2, characterized in that: The adjustment parameters include a first angle adjustment parameter, a second angle adjustment parameter and a first posture adjustment parameter. The control module is used to adjust the placement angle of the first reflector according to the first angle adjustment parameter, adjust the placement angle of the second reflector according to the second angle adjustment parameter, and adjust the placement angle and / or placement position of the first beam splitter according to the first posture adjustment parameter.

5. The interference exposure system according to claim 1, characterized in that: The beam adjustment module includes: a first displacement prism, a second displacement prism and a convex lens; The first displacement prism is located on the optical path of the first coherent light beam, and the first displacement prism is used to adjust the beam width of the first coherent light beam; The second displacement prism is located on the optical path of the second coherent light beam, and the second displacement prism is used to adjust the beam width of the second coherent light beam; The convex lens is located on the optical paths of the adjusted first coherent light beam and the second coherent light beam, and is used to adjust the optical path of the adjusted first coherent light beam to obtain the third coherent light beam, and to adjust the optical path of the adjusted second coherent light beam to obtain the fourth coherent light beam.

6. The interference exposure system according to claim 5, characterized in that: The adjustment parameters include a fourth angle adjustment parameter and a fifth angle adjustment parameter, and the control module is used to adjust the placement angle of the first displacement prism according to the fourth angle adjustment parameter, and to adjust the placement angle of the second displacement prism according to the fifth angle adjustment parameter.

7. The interferometric exposure system according to any one of claims 1 to 6, wherein the period measurement module comprises: Interference exposure components, base station, image acquisition unit and processing unit; The interference exposure component is disposed on the base, and the interference exposure component is located on the optical paths of the third coherent light beam and the fourth coherent light beam, and the third coherent light beam and the fourth coherent light beam form the interference fringes through the interference exposure component; The image acquisition unit is used to acquire a first fringe image of the interference fringe; The base is used to drive the interference exposure assembly to move a target distance, where the target distance is a preset multiple of an empirical value of a fringe period of interference fringes formed by the first coherent light beam and the second coherent light beam; The image acquisition unit is used to acquire a second fringe image of interference fringes formed by the interference exposure component after the third coherent light beam and the fourth coherent light beam are moved; The processing unit is used to determine the fringe period of the interference fringes according to the first fringe image and the second fringe image of the interference fringes and the target distance.

8. According to the interference exposure system of claim 7, the interference exposure component is a second beam splitter, and the second beam splitter is used to reflect and transmit the third coherent light beam and the fourth coherent light beam so that the third coherent light beam and the fourth coherent light beam passing through the second beam splitter form the interference fringes.

9. The interference exposure system according to claim 7, characterized in that: The interference exposure component is a diffraction grating, which is used to reflect and transmit the third coherent light beam incident from the first side and the fourth coherent light beam incident from the second side, so that the transmitted light beam and the reflected light beam of the same diffraction order of the third coherent light beam and the fourth coherent light beam form the interference fringes.

10. An interference exposure method, characterized in that: Applied to the interference exposure system according to any one of claims 1 to 9, the method comprises: Outputting a first coherent light beam and a second coherent light beam through the coherent light source module, wherein a beam angle between the first coherent light beam and the second coherent light beam is a first angle; The optical path of the first coherent light beam is adjusted by the light beam adjustment module to obtain a third coherent light beam, and the optical path of the second coherent light beam is adjusted to obtain a fourth coherent light beam, wherein a beam angle between the third coherent light beam and the fourth coherent light beam is a second angle, and the second angle is smaller than the first angle; Detecting the fringe period of interference fringes formed by the third coherent light beam and the fourth coherent light beam by the period measurement module; The control module determines corresponding adjustment parameters according to the fringe period, and adjusts the beam adjustment module according to the adjustment parameters so that the fringe period of the interference fringes formed by the third coherent light beam and the fourth coherent light beam meets a preset period accuracy.

11. A grating exposure system, characterized in that: The grating exposure system includes a substrate to be prepared into a grating structure and an interference exposure system as described in any one of claims 1 to 9, wherein the substrate is arranged on a target position of a base, and the target position is located on the optical path of the third coherent light beam and the fourth coherent light beam output by the adjusted beam adjustment module, so that the third coherent light beam and the fourth coherent light beam form interference fringes on the substrate whose fringing period satisfies the preset period accuracy.

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