Multi-focus translation staggered close connection type parallel laser direct writing rapid machining method

Abstract

The invention discloses a multi-focus translation staggered close connection type parallel laser direct writing rapid processing method which comprises the steps that a multi-focus module and a laser direct writing scanning device are built, the multi-focus module generates multi-beam arrays which are arranged in parallel, and after the multi-beam arrays are focused by the laser direct writing scanning device, multi-focus laser arrays which are arranged in parallel at equal intervals are formed at a focal plane; a multi-focus translation staggered scanning strategy is designed, and in the scanning strategy, direct-writing machining areas of all focuses are interspersed and staggered, so that a close-connection direct-writing machining area is formed; the multi-focus laser arrays arranged in parallel at equal intervals perform scanning through a scanning strategy, in the scanning process, each focus is controlled through an independent laser switch of the focus, the multi-focus laser arrays interact with a photoetching material, and rapid laser direct writing of any pattern to be processed is achieved in a close connection direct writing processing area. According to the invention, one-mirror-to-bottom type seamless laser direct-writing scanning can be realized, and the multi-focus laser direct-writing processing efficiency and quality can be effectively improved.

Description

Technical Field

[0001] The present invention relates to the field of optical precision micro-nano processing, and in particular to a multi-focus translational staggered close-contact parallel laser direct writing rapid processing method. Background Art

[0002] Laser direct writing technology, due to its advantages such as high processing resolution, three-dimensional processing capabilities, and the absence of a vacuum, is widely used in the fabrication and processing of ultra-fine micro- and nanostructures, such as integrated optical chips, microfluidic devices, and metasurface structures. However, due to its low optical throughput, laser direct writing suffers from technical drawbacks such as low processing efficiency and poor stability when processing large-area patterns.

[0003] To improve the processing efficiency of laser direct writing technology, increasing the number of writing laser beams to achieve parallel multi-focus laser direct writing is the most effective technical approach. Currently, there are many mature technologies for producing parallel multi-focus laser direct writing arrays, such as fiber arrays, multi-channel AOMs, DMDs, and SLMs. By increasing the number of parallel focal points, the throughput and efficiency of laser direct writing processing can be improved.

[0004] For example, Chinese patent document CN101477306A discloses a high-speed multi-beam parallel laser direct writing device suitable for micro-nano processing, which provides multi-beam laser parallel high-speed writing, greatly improving the writing speed.

[0005] Chinese patent document CN102621823A discloses a multi-beam parallel laser direct writing device and a direct writing method thereof, which are suitable for the processing and industrial production of large-area periodic micro-nano optical structures.

[0006] However, the increase in the number of focal spots undoubtedly puts higher requirements on the scanning strategy of laser direct writing technology. The existing multi-focus laser direct writing method is more suitable for micro-nano processing of periodic graphics. For the processing of arbitrary graphics, it is usually achieved by processing each focus area in blocks. It is inevitable that splicing marks will be generated between the blocks, affecting the processing quality of the graphics. Summary of the Invention

[0007] The present invention provides a multi-focus translational staggered close-contact parallel laser direct writing rapid processing method, which can realize "one-mirror-to-the-end" seamless laser direct writing scanning, effectively improving the multi-focus laser direct writing processing efficiency and processing quality.

[0008] A multi-focus translational staggered close-contact parallel laser direct writing rapid processing method comprises the following steps:

[0009] S1. Build a multi-focus laser direct writing device, including a multi-focus module and a laser direct writing scanning module. The multi-focus module generates a multi-beam array arranged in parallel. After being focused by the laser direct writing scanning module, a multi-focus laser array arranged in parallel and at equal intervals is formed at the focal plane for pattern writing on the photolithographic material.

[0010] S2, design a multi-focus translation interlaced scanning strategy, in which the direct writing processing areas of each focus are interlaced with each other to form a close direct writing processing area;

[0011] S3, a multi-focus laser array arranged in parallel with equal spacing is scanned using a designed scanning strategy. During the scanning process, each focus is controlled by its independent laser switch. The multi-focus laser array interacts with the photolithographic material to achieve rapid laser direct writing of any graphics to be processed in the close direct writing processing area.

[0012] Optionally, in step S1, the multi-focus module uses an optical fiber array, a multi-channel acousto-optic modulator (AOM), a digital micromirror device (DMD), or a spatial light modulator (SLM) to generate a parallel array of multiple beams; the beam corresponding to each focus is controlled by an independent laser switch.

[0013] In step S1, the laser direct writing scanning module includes a scanning device and a focusing lens;

[0014] Among them, the focusing objective is used to focus the parallel arranged multi-beam array, forming a parallel and equally spaced multi-focus laser array at the focal plane; the scanning device is used to control the multi-focus laser array to scan according to the scanning strategy, and the scanning method adopts translation stage scanning, galvanometer scanning or rotating mirror scanning.

[0015] The multi-focus module generates a parallel array of multi-beams, which are divided into two paths by a beam splitter. One path is incident on the power stabilization module for optimizing laser power fluctuations, and the other path is incident on the scanning device for scanning control of laser direct writing; the laser beam emitted by the scanning device passes through the focusing objective lens to form a parallel and equally spaced multi-focus laser array at the focal plane.

[0016] The multi-focus laser direct writing device also includes an auxiliary device, which includes a power stabilization module, a fixed-focus laser beam module, an imaging observation module and a fixed-focus module;

[0017] The fixed-focus laser beam module generates a collimated fixed-focus laser beam and illuminating white light. After passing through the first beam splitter and the second beam splitter, it is focused by the focusing objective lens to illuminate the surface of the processing area and then reflected. After being collected by the focusing objective lens, it is transmitted again through the second beam splitter and the first beam splitter, and finally divided into two beams by the third beam splitter. One beam is incident on the imaging observation module for real-time observation of the surface of the processing area; the other beam is incident on the fixed-focus module, which measures the focus of the focused beam in real time and feeds back the measurement signal changes to the translation stage.

[0018] The power stabilization module separates part of the laser from the main optical path through a beam splitter, measures the intensity and angle of the laser in real time, and feeds it back to the main optical path for real-time adjustment to optimize the laser power stability.

[0019] The imaging observation module consists of an imaging lens and an imaging detector, and is used to observe the interaction between the laser and the photolithography material during the laser direct writing process.

[0020] The fixed focus module introduces another fixed focus laser beam and uses a specific fixed focus method to achieve rapid search and real-time locking of the laser direct writing focal plane, ensuring the line width consistency of laser direct writing processing.

[0021] The focusing methods used by the fixed focus module include differential confocal focusing method, four-image fixed focusing method, triangular focusing method, etc.

[0022] In step S2, the designed multi-focus translation interlaced scanning strategy specifically includes:

[0023] The number of focal points of the multi-focus laser array is i, the spacing between each focal point is αμm, and they are evenly arranged along the Y direction of the processing plane;

[0024] The multi-focus laser array is controlled to scan along the X direction of the processing plane, and the Y direction uses the translation stage to jump or move at a constant speed to expand the processing area. When completing a single X-direction scan of the multi-focus array, the single movement distance in the Y direction is mμm.

[0025] Continuous staggered scanning is performed in this manner. After the scanning is completed, the non-closely connected areas at the beginning and end are removed to obtain the closely connected direct writing processing area in the middle.

[0026] The designed multi-focus translation and interlaced scanning strategy must satisfy the following parameter relationships:

[0027]

[0028] Wherein, k is an integer coprime with i; γ = m / β, β is the line width of each focus processing area, unit is μm; n is the number of single focus processing areas that can be filled between the focuses, n = α / β, and n is greater than 2.

[0029] The specific step-jumping method of the translation stage is as follows: after a single X-direction scan of the multi-focus laser array is completed, the translation stage adopts a step-jumping method and moves mμm at a time in the Y direction in a short period of time;

[0030] The uniform motion of the translation stage is as follows: while the multi-focus laser array performs a single X-direction scan, the translation stage also moves uniformly in the Y-direction, and within the time interval t between two consecutive X-direction scans of the multi-focus laser array, the displacement in the Y-direction is m μm.

[0031] Compared with the prior art, the present invention has the following beneficial effects:

[0032] This invention utilizes a "one-lens-through," multi-focus, translational, staggered, and close-contact laser direct writing scanning strategy to convert the increased optical throughput of multi-focus laser direct writing technology into improved laser direct writing processing efficiency, while simultaneously avoiding the generation of numerous splicing marks during multi-focus, multi-block laser direct writing. This improves laser direct writing processing efficiency while ensuring the quality of the processed images. Finally, the method of this invention is highly universal and applicable to multi-focus femtosecond laser direct writing technology, multi-focus continuous light laser direct writing technology, and multi-focus edge light blocking and suppression technology. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 Schematic diagram of the multi-focus direct writing processing area in an embodiment of the present invention.

[0034] Figure 2 Schematic diagram of a multi-focus translation and interlaced scanning strategy in an embodiment of the present invention.

[0035] Figure 3 Schematic diagram of a multi-focus laser direct writing device in an embodiment of the present invention.

[0036] Figure 4 Schematic diagram of different multi-focus generation methods of the multi-focus module in an embodiment of the present invention.

[0037] Figure 5 Schematic diagram of different scanning modes of a scanning device in an embodiment of the present invention.

[0038] Figure 6 Schematic diagram of a multi-focus laser direct writing device based on an optical fiber array in an embodiment of the present invention.

[0039] Figure 7 Schematic diagram of a multi-focus module of a multi-channel acousto-optic modulator coupled to a fiber array in an embodiment of the present invention. DETAILED DESCRIPTION

[0040] The present invention will be described in further detail below with reference to the accompanying drawings and examples. It should be noted that the following examples are intended to facilitate understanding of the present invention and do not have any limiting effect on the present invention.

[0041] like Figure 1 As shown in FIG, a schematic diagram of a multi-focus direct writing processing area is shown. In this embodiment, a four-focus laser beam is used as an illustration. In actual operation, this rapid laser direct writing processing method is applicable to laser direct writing systems with different numbers of focuses. After the light beams 105 to 108 pass through the focusing system, they form focuses 101 to 104 on the substrate 109 for laser direct writing processing. It should be noted that the direction of the line connecting the focuses 101 to 104 can be completely perpendicular to the scanning direction 110, or it can be as shown in FIG. Figure 1 As shown in , they are arranged at a certain angle to the scanning direction.

[0042] The line width of the direct writing processing area of ​​a single focus is βμm, where the line width of the direct writing area is related to the focus size and the response of the photoresist; the spacing between adjacent focuses (such as Figure 1 The projection distance between the center focus 101 and the focus 102 along the direction perpendicular to the scanning direction is αμm. The multiple focus points 101-104 are moved along the scanning direction 110 by the scanning element, ultimately forming corresponding direct writing areas 111-114 with a length of δμm. As a set of direct writing areas, the distance between adjacent direct writing areas is αμm.

[0043] like Figure 2 As shown in the figure, it is a schematic diagram of the multi-focus translation and staggered scanning strategy. Figure 1 The multi-focus direct writing processing area in the image is regarded as a set of direct writing area sets. After the direct writing processing of a set of direct writing area sets is completed on the substrate 201, the relative position of the direct writing sample and the beam focus is moved mμm in the vertical direction of the scanning direction by a displacement stage or a scanning element, as shown in FIG. Figure 2 As shown in .

[0044] It should be noted that the movement along the vertical scanning direction can adopt the jump-step method of the translation stage or the uniform motion method of the translation stage, wherein the jump-step method means that after the direct writing of the previous set of direct writing area sets is completed, the translation stage or the scanning element causes the relative position of the direct writing sample and the focus of the light beam to move mμm in the direction perpendicular to the scanning direction in the time interval before the direct writing of the next set of direct writing area sets begins. The uniform motion method means that within the processing time t required from the start of direct writing of the current set of direct writing area sets to the start of direct writing of the next set of direct writing area sets, the translation stage or the scanning element causes the relative position of the direct writing sample and the focus of the light beam to move mμm in the direction perpendicular to the scanning direction through continuous uniform motion. The processing method using the uniform motion method of the translation stage will cause a certain tilt of the direct writing pattern, but usually because the length δμm of the processing area is much larger than the displacement mμm in the vertical direction, the tilt can be ignored.

[0045] According to the aforementioned translational interleaving method, the spacing between each set of direct-writing regions is mμm, and the direct-writing regions are staggered to form a close-contact laser direct-writing processing area. However, due to the limited number of translational interleavings, some areas within the initial and final direct-writing regions do not form a close-contact laser direct-writing processing area. Therefore, by rapidly controlling the laser switch, the pattern 202 to be processed forms the corresponding laser direct-writing pattern within the close-contact processing area.

[0046] At the same time, in order to achieve a close arrangement of the direct writing area, the following equation must be satisfied:

[0047]

[0048] Wherein, k is an integer relatively prime to i, and γ=m / β; otherwise, a certain gap in direct writing processing will occur.

[0049] like Figure 3 Figure 2 shows a schematic diagram of the structure of a multi-focus laser direct writing device used in an embodiment of the present invention. This device adopts a modular design and primarily comprises a multi-focus module 301, a laser direct writing scanning module, and auxiliary devices. The laser direct writing scanning module includes a scanning device 304 and a focusing lens 306; the auxiliary devices include a power stabilization module 303, a fixed-focus laser beam module 309, an imaging observation module 311, and a fixed-focus module 312.

[0050] The multi-focus module 301 generates a multi-beam array, which is split into two beams by a beam splitter 302. One beam is incident on the power stabilization module 303 to optimize laser power fluctuations during the multi-focus pattern direct writing process, while the other beam is incident on the scanning device 304 for scanning control of the laser direct writing process. The laser beam emitted by the scanning device 304 passes through the focusing objective lens 306 to form an equidistant multi-focus array on the surface of the direct writing sample. Combining scanning device control with a multi-focus translation and interleaved scanning strategy, rapid laser direct writing processing is achieved.

[0051] The fixed-focus laser beam module 309 generates a collimated fixed-focus laser beam and illuminating white light, which passes through the first beam splitter 308 and the second beam splitter 305, and is focused by the focusing objective lens 306 to illuminate the surface of the direct-writing sample. The laser reflected by the substrate is collected by the focusing objective lens 306, and is transmitted again through the second beam splitter 305 and the first beam splitter 308, and finally divided into two beams by the third beam splitter 310, one of which is incident on the imaging observation module 311 for real-time observation of the direct-writing sample surface; the other beam is incident on the fixed-focus module 312, and the focus of the fixed-focus beam is measured in real time by the fixed-focus module 312, and the measurement signal change is fed back to the translation stage for real-time supplementation of the direct-writing focal plane offset of the system.

[0052] like Figure 4The figure shows a schematic diagram of different multi-focus generation methods of the multi-focus module, mainly the optical fiber array generation method and the optoelectronic modulation device generation method.

[0053] Fiber array generation method Figure 4 As shown in a), the laser arrays 401 are coupled into the corresponding optical fiber bundles 402 respectively, and the laser output ports at the other ends of the optical fiber bundles 402 are coupled and docked into the optical fiber array 403, with the laser beams 402 being arranged in an equidistant periodic pattern. The laser beams 402 are emitted from the output ends of the optical fiber array 403, forming the multi-beam array 404 required for the multi-focus rapid laser direct writing method.

[0054] The photoelectric modulation device is produced as follows Figure 4 As shown in b), the laser module 405 emits a collimated laser beam to illuminate the optoelectronic modulation device 406 (the optoelectronic modulation device includes DMD, SLM, etc.), and the optoelectronic modulation device 406 modulates the collimated laser beam into a multi-beam array 407 for multi-focus rapid laser direct writing.

[0055] like Figure 5 As shown in FIG, there are different scanning modes of the scanning device, which mainly include translation stage scanning, galvanometer scanning and rotating mirror scanning. Figure 5 Middle (a) shows the scanning method of the translation stage. The focused laser beam 501 does not need to be moved, and the processing pattern is engraved by moving the translation stage 502. Since the translation stage can move long distances, "one-shot" nano-pattern processing can be achieved. For the processing of large-area patterns, the splicing marks are minimal. Figure 5 Middle b) shows the galvanometer scanning method. The photolithography sample 504 is stationary, and the focal spot moves on the sample surface by changing the angle of the galvanometer 503. This method has a fast processing rate, but is limited by the size of the focusing objective lens entrance pupil. The processing of large-area graphics will have more splicing marks. Figure 5 Figure c) shows the rotating mirror scanning method. The photolithography sample 506 is stationary, and the rotation angle of the rotating mirror 505 changes, causing the focal spot to move on the sample surface. This method has the fastest processing rate, but is limited by the size of the focusing objective lens entrance pupil and the instability of the rotating mirror. The processing of large-area graphics will have more splicing marks and processing deviations.

[0056] The embodiment of the present invention also shows a multi-focus laser direct writing device based on an optical fiber array, such as Figure 6As shown. The multi-focus module includes a laser group 601, a fiber bundle group 602, and a fiber array 603. The laser group 601 outputs lasers respectively and couples them to the corresponding fiber bundle group 602. The laser output end of the fiber bundle group 602 is connected to the fiber array 603 to output an equally spaced multi-beam array. The multi-beam array is collimated and transmitted for a distance by the lens 604, focused by the lens 605, and collimated again by the lens 606. It is reflected by the reflector 607 and focused by the focusing objective lens 608 to form a multi-focus array 609, which acts on the lithography sample 611 to realize the multi-beam direct writing process 610. Through the scanning method of the displacement stage, the switch of the laser group 601 and the long-distance scanning method of the displacement stage are synchronously controlled by the board card, combined with the multi-focus translation and staggered close-contact laser direct writing algorithm, a "one-mirror-to-the-end" type of fast laser direct writing processing without splicing marks is realized.

[0057] It should be noted that Figure 6 The multi-focus laser direct writing device only shows the multi-focus module and laser direct writing scanning module. In actual application, it needs to be combined with Figure 3 The various auxiliary devices mentioned in, such as the focusing device, can adopt the differential confocal focusing method, the four-image fixed focusing method, the triangular focusing method, etc.

[0058] like Figure 7 The figure shows a multi-focus module of a multi-channel acousto-optic modulator coupled with a fiber array, which is used to replace Figure 6 The high-power laser 701 outputs laser light, which is coupled to the multi-channel acousto-optic modulator 703 through the optical fiber 702 and is divided into multiple laser paths. Each laser path is modulated by an independent acousto-optic modulator and then transmitted to the optical fiber array 705 through the optical fiber bundle group 704 to realize the output of an equidistant multi-beam array. This method has a higher modulation rate. Finally, through the scanning of the translation stage and the synchronous control of the multi-channel acousto-optic modulator, combined with the multi-focus translational staggered close-contact laser direct writing algorithm, a "one-shot to the end" fast laser direct writing process without splicing marks is realized. It should be noted that this method is Figure 6 In practical applications, both solutions can achieve the required functions, or a hybrid of the two solutions can be used as a multi-focus module.

[0059] The embodiments described above provide a detailed description of the technical solutions and beneficial effects of the present invention. It should be understood that the above are only specific embodiments of the present invention and are not intended to limit the present invention. Any modifications, supplements and equivalent substitutions made within the scope of the principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A multi-focus translational staggered close-contact parallel laser direct writing rapid processing method, characterized in that: The following steps are involved: S1. Build a multi-focus laser direct writing device, including a multi-focus module and a laser direct writing scanning module. The multi-focus module generates a multi-beam array arranged in parallel. After being focused by the laser direct writing scanning module, a multi-focus laser array arranged in parallel and at equal intervals is formed at the focal plane for pattern writing on the photolithographic material. S2, design a multi-focus translation interlaced scanning strategy, in which the direct writing processing areas of each focus are interlaced with each other to form a close direct writing processing area; S3, a multi-focus laser array arranged in parallel with equal spacing is scanned using a designed scanning strategy. During the scanning process, each focus is controlled by its independent laser switch. The multi-focus laser array interacts with the photolithographic material to achieve rapid laser direct writing of any graphics to be processed in the close direct writing processing area.

2. The multi-focus translational staggered close-contact parallel laser direct writing rapid processing method according to claim 1, characterized in that: In step S1, the multi-focus module uses an optical fiber array, a multi-channel acousto-optic modulator (AOM), a digital micromirror device (DMD), or a spatial light modulator (SLM) to generate a parallel array of multiple beams; the beam corresponding to each focus is controlled by an independent laser switch.

3. The multi-focus translational staggered close-contact parallel laser direct writing rapid processing method according to claim 1, characterized in that: In step S1, the laser direct writing scanning module includes a scanning device and a focusing lens; Among them, the focusing objective is used to focus the parallel arranged multi-beam array, forming a parallel and equally spaced multi-focus laser array at the focal plane; the scanning device is used to control the multi-focus laser array to scan according to the scanning strategy, and the scanning method adopts translation stage scanning, galvanometer scanning or rotating mirror scanning.

4. The multi-focus translational staggered close-contact parallel laser direct writing rapid processing method according to claim 3, characterized in that: The multi-focus module generates a parallel array of multi-beams, which are divided into two paths by a beam splitter. One path is incident on the power stabilization module for optimizing laser power fluctuations, and the other path is incident on the scanning device for scanning control of laser direct writing; the laser beam emitted by the scanning device passes through the focusing objective lens to form a parallel and equally spaced multi-focus laser array at the focal plane.

5. The multi-focus translational staggered close-contact parallel laser direct writing rapid processing method according to claim 4, characterized in that: The multi-focus laser direct writing device also includes an auxiliary device, which includes a power stabilization module, a fixed-focus laser beam module, an imaging observation module and a fixed-focus module; The fixed-focus laser beam module generates a collimated fixed-focus laser beam and illuminating white light. After passing through the first beam splitter and the second beam splitter, it is focused by the focusing objective lens to illuminate the surface of the processing area and then reflected. After being collected by the focusing objective lens, it is transmitted again through the second beam splitter and the first beam splitter, and finally divided into two beams by the third beam splitter. One beam is incident on the imaging observation module for real-time observation of the surface of the processing area; the other beam is incident on the fixed-focus module, which measures the focus of the focused beam in real time and feeds back the measurement signal changes to the translation stage.

6. The multi-focus translational staggered close-contact parallel laser direct writing rapid processing method according to claim 1, characterized in that: In step S2, the designed multi-focus translation and interlaced scanning strategy specifically includes: The number of focal points of the multi-focus laser array is i, the spacing between each focal point is αμm, and they are evenly arranged along the Y direction of the processing plane; The multi-focus laser array is controlled to scan along the X direction of the processing plane, and the Y direction uses the translation stage to jump or move at a constant speed to expand the processing area. When completing a single X-direction scan of the multi-focus array, the single movement distance in the Y direction is mμm. Continuous staggered scanning is performed in this manner. After the scanning is completed, the non-closely connected areas at the beginning and end are removed to obtain the closely connected direct writing processing area in the middle.

7. The multi-focus translational staggered close-contact parallel laser direct writing rapid processing method according to claim 6, characterized in that: The designed multi-focus translation and interlaced scanning strategy must satisfy the following parameter relationships: Wherein, k is an integer coprime with i; γ = m / β, β is the line width of each focus processing area, unit is μm; n is the number of single focus processing areas that can be filled between the focuses, n = α / β, and n is greater than 2.

8. The multi-focus translational staggered close-contact parallel laser direct writing rapid processing method according to claim 6, characterized in that: The specific step-jumping method of the translation stage is as follows: after a single X-direction scan of the multi-focus laser array is completed, the translation stage adopts a step-jumping method and moves mμm at a time in the Y direction in a short period of time.

9. The multi-focus translational staggered close-contact parallel laser direct writing rapid processing method according to claim 6, characterized in that: The uniform motion of the translation stage is as follows: while the multi-focus laser array performs a single X-direction scan, the translation stage also moves uniformly in the Y-direction, and within the time interval t between two consecutive X-direction scans of the multi-focus laser array, the displacement in the Y-direction is m μm.

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