CN-122018241-A - Axial parallel laser direct-writing lithography method and system with programmable phase regulation

CN122018241ACN 122018241 ACN122018241 ACN 122018241ACN-122018241-A

Abstract

The invention discloses a programmable phase-regulated axial parallel laser direct-writing lithography method and a system, wherein the system utilizes a constructed ring-phase mapping relation and a ring boundary index table to divide an effective illumination area of a spatial light modulator into a plurality of concentric rings, and each concentric ring corresponds to 0 or 0 The phase corresponds to the phase distribution of the SLM pupil plane on the SLM, so that a genetic algorithm is associated with the phase pattern loaded on the SLM, the result of genetic algorithm optimization can be efficiently converted into the phase pattern, then a plurality of SLM pupil plane phase distributions which are uniform in strength, good in side lobe inhibition and high in resolution and correspond to light focuses can be efficiently generated in the axial direction by utilizing the genetic algorithm based on the constructed fitness function, and therefore axial parallel laser direct writing lithography is realized, simultaneous generation of multiple focuses is guaranteed, and engineering availability balance among strength balance, side lobe control and processing robustness can be achieved.

Inventors

ZHUANG WENQI
KUANG CUIFANG
WEN JISEN
LUO MENGDI
LIU XU
SHEN WEIDONG

Assignees

浙江大学

Dates

Publication Date: 20260512
Application Date: 20260119

Claims (10)

1. A programmable phase-modulated axial parallel laser direct-write lithography method, comprising: (1) Dividing an effective illumination area of the SLM into n concentric rings according to the effective illumination diameter and the pixel size of the SLM, and constructing a ring boundary index table based on the mapping relation between the radius of the concentric rings and the concentric rings; (2) Generating a plurality of individuals constructed by n binary numbers corresponding to concentric rings by utilizing a random number generator to obtain an initial population, decoding each individual in the initial population to obtain n 0 or pi phases so as to obtain a ring-phase mapping relation, forming SLM pupil plane phase distribution based on the ring-phase mapping relation and a ring boundary index table, completing one-time regularization restoration, and calling a light field evaluation module to calculate and evaluate an axial light field and a transverse light field corresponding to each individual in a set sampling area to obtain the light field energy distribution and the full width at half maximum of each individual in a target window area; (3) Constructing a fitness function based on the set optimization target and constraint item capable of realizing uniform focal energy, obtaining a fitness value of each individual based on the light field energy distribution and full width at half maximum corresponding to each individual through the fitness function, and screening parent individuals from the current population by adopting a tournament selection mechanism based on the fitness value of each individual; (4) Performing crossover and mutation operations on the screened parent individuals to generate child new individuals, and combining the child new individuals with the screened parent to form a new population; (5) Judging whether the preset maximum iteration times are reached or not, or if the fitness difference value is lower than a preset threshold value, stopping iteration to obtain the phase distribution of the SLM pupil surface corresponding to the individual with the highest fitness value, otherwise, repeating the steps (2) - (4); (6) And (3) quantizing and encoding the phase distribution of the SLM pupil plane obtained in the step (5), generating a phase diagram matched with the driving mode of the SLM, and loading the phase diagram to the SLM, thereby realizing axial parallel laser direct writing lithography.
2. The programmable phase-modulated axial parallel laser direct write lithography method of claim 1, wherein forming the SLM pupil plane phase profile based on the ring-to-phase mapping relationship and the ring boundary index table comprises: Determining the inner radius, the outer radius and the ring width corresponding to each concentric ring through a ring boundary index table, and determining the pixel positions covered by the corresponding concentric rings in the SLM pixel array based on the inner radius, the outer radius and the ring width; based on the ring-phase mapping relationship, corresponding phase values are assigned to each pixel within the concentric ring, thereby constructing an SLM pupil plane phase distribution.
3. The programmable phase-modulated axial parallel laser direct-write lithography method of claim 1, wherein the regularized repair is required after the SLM pupil plane phase distribution is obtained; The regular repair comprises the steps of carrying out constraint processing on continuity and manufacturability on phase distribution of the SLM pupil plane, eliminating discontinuous or abrupt phase boundaries by limiting phase abrupt changes between adjacent concentric rings, merging or correcting isolated phase areas smaller than a preset minimum annular width to ensure that a phase structure meets pixel resolution and manufacturing requirements of a spatial light modulator, and carrying out smoothing processing on isolated phase points or isolated phase areas which introduce abnormal diffraction effects in the phase distribution to reduce high-frequency components.
4. The programmable phase-regulated axial parallel laser direct-write lithography method according to claim 1, wherein after the light field energy distribution and the full width at half maximum of each individual in the target window area are obtained, normalization processing is performed on the light field energy distribution and the full width at half maximum in the target window area, and the fitness value of each individual is obtained by inputting the normalized value into a fitness function.
5. The programmable phase-regulated axial parallel laser direct-write lithography method of claim 1, wherein the fitness value is constructed by a basic cost function and a total penalty term together, wherein the basic cost function is obtained by weighted summation of performance indexes of a plurality of optimization targets; The basic cost function comprises three optimization targets, wherein the performance index of a first optimization target is an average value of the sum of the inverse of the actual energy proportion of each target focus in a target window area and is used for inhibiting energy imbalance among focuses, the performance index of a second optimization target is an absolute value sum of the difference between the actual energy proportion of each target focus in the target window area and the expected energy proportion and is used for restraining the energy distribution of the focuses to be close to an expected proportion, and the performance index of a third optimization target is an average value of the ratio of the full width at half maximum and the working wavelength of the transverse section of the light field of each target focus in the corresponding axial position in the target window area and is used for improving transverse focusing resolution; The total penalty term is obtained by weighting and summing penalty values corresponding to all constraint conditions, and all penalty values are non-negative and smaller represent higher constraint satisfaction degree; And the fitness value is obtained by monotonous transformation of the basic cost function and the total penalty term, so that the larger the fitness value is, the better the comprehensive performance of the individual is.
6. The programmable phase-modulated axial parallel laser direct write lithography method of claim 5, wherein said constraint terms include the following: , wherein, Is the first The central positions of the target focuses are used as centers, and an evaluation interval is preset in the axial direction and is used for limiting an axial target window of each target focus; indicating the direction along the optical axis Normalized axial light intensity distribution at the location; is the first The actual energy duty cycle of the individual target foci; The number of the target focuses; is the first Normalizing peak values in the target focuses; Represent the first Desired energy duty cycles corresponding to the individual target foci; is the first Radial ring spacing between adjacent concentric rings; the minimum allowable ring spacing is preset according to the pixel size of the spatial light modulator and the manufacturing capability of the system.
7. The programmable phase-modulated axial parallel laser direct write lithography method of claim 5, wherein the three optimization objectives are as follows: , wherein, The number of the target focuses; is the first The actual energy duty cycle of the individual target foci; is the first Desired energy duty cycles for the individual target foci; is the first Full width at half maximum of the light field transverse profile at the corresponding axial position of each target focus; Is the operating wavelength.
8. The programmable phase-modulated axial parallel laser direct-write lithography method of claim 1, wherein a crossover strategy capable of maintaining a phase block structure is employed after generation of a child new individual, and manufacturability repair rules are executed immediately after the mutation operation is completed to ensure feasibility of the child individual, wherein: taking a phase block formed by concentric rings or a plurality of adjacent concentric rings as a minimum genetic unit, selecting one or more complete phase blocks from a parent individual as cross segments, and carrying out integral exchange at corresponding positions, thereby avoiding random crossing of single pixels or single ring elements and ensuring the continuity of the phase structure in the radial direction; The manufacturability restoration rule comprises the steps of detecting a phase structure generated after crossing and mutation, merging or adjusting the phase structure when the condition that the distance between adjacent concentric rings is smaller than the preset minimum allowable ring width exists, correcting or smoothing an isolated phase block or an abnormal phase region introduced by crossing or mutation to reduce a high-frequency phase component, and carrying out consistency check on the restored phase structure to ensure that the pixel resolution and the system stability requirements of the spatial light modulator are met.
9. The method of programmable phase-modulated axial parallel laser direct write lithography according to claim 1, wherein the obtained optical parameters include the incident wavelength before dividing the SLM active illumination area into n concentric rings The determined operation constraint comprises the effective illumination diameter of the SLM, the pixel size and the spacing of the SLM, and the set of axial target focuses Wherein the number of target focuses is First, the The focus center positions are Adjacent spacing and half width of window 。
10. An axially parallel laser direct write lithography system according to a programmable phase-modulated axially parallel laser direct write lithography method of any one of claims 1-9, comprising: the laser is used for providing a laser light source for presetting the laser direct writing incident wavelength; the first 4f system is used for shrinking the laser beam to a preset multiple; The exposure switch module is used for performing polarization angle modulation on the laser beam after beam shrinking, executing an exposure switch function in laser direct writing processing through the acousto-optic modulator, correcting the polarization direction of first-order diffraction light emitted by the acousto-optic modulator, blocking diffraction light of other orders, and transmitting the first-order diffraction light; The polarized beam splitter, the second 4f system and the spatial modulator, wherein the first-order diffraction light irradiates the spatial modulator after passing through the polarized beam splitter and the second 4f system, and the spatial modulator loads the programmable phase-regulated axial parallel laser direct-write lithography method according to any one of claims 1-9 to obtain SLM pupil plane phase distribution to carry out phase modulation on the incident laser beam; A third 4f system, a galvanometer scanning system, wherein the third 4f system is used for irradiating the laser beam after phase modulation to the galvanometer scanning system, and the galvanometer scanning system is used for performing deflection scanning on the laser beam based on a control instruction; and the direct writing module is used for expanding the laser beam after polarization scanning, and converging the laser beam after expanding to a sample to be written of the displacement platform to realize axial parallel laser direct writing lithography.

Description

Axial parallel laser direct-writing lithography method and system with programmable phase regulation Technical Field The invention belongs to the field of laser direct-writing lithography, and particularly relates to an axial parallel laser direct-writing lithography method and system with programmable phase regulation. Background The laser direct writing lithography performs local exposure in photoresist or polymerizable material through focusing light beams, and the technology is used as a maskless, flexible and efficient lithography technology, and has great application potential in the fields of micro-nano device research and development, photon chip manufacturing, biomedicine and the like. The traditional scheme of laser direct writing lithography is mostly dependent on single focus scanning, multiple focusing and layer-by-layer exposure are needed when writing a multilayer structure, and the traditional scheme has the inherent bottleneck of low processing efficiency and higher requirement on system stability. At present, axial multi-focus schemes based on diffraction optical elements or fixed phase plates have been proposed, but once the static optical elements are machined, the optical functions of the static optical elements are fixed, the number, the position and the intensity distribution of focuses cannot be flexibly adjusted, meanwhile, the overall debugging complexity of the system is improved, and complex machining requirements are difficult to adapt. The invention discloses a three-dimensional laser direct writing method and system based on high flux of square multimode fibers, wherein an optical fiber array formed by a plurality of square multimode fibers is used as a laser direct writing head, each square multimode fiber utilizes a spatial light modulator to perform phase modulation on a light field of an incident square multimode fiber according to a loaded calculated phase diagram, focusing is realized on an emergent surface, focused laser is used for performing three-dimensional laser direct writing on an object to be processed, the calculated phase diagram corresponding to each square multimode fiber is obtained by optimizing through a set focusing position by utilizing a closed loop iterative genetic algorithm, and the focusing position of emergent laser of each square multimode fiber is set according to processing errors when the optical fiber array is arranged. By utilizing the characteristic that square multimode optical fibers can be compactly arranged, the system can be expanded into multiple channels, so that parallel direct writing of multiple channels is realized, the direct writing efficiency is further improved, and the problems of low direct writing speed, low resolution and the like of the conventional laser direct writing system are solved. The solution disclosed in this patent application does not enable axial parallel laser direct write lithography. The invention patent application with publication number of CN115598833A discloses a method for generating a long-focus deep super-resolution optical needle and a high-depth-to-width ratio laser direct writing system, which adopts the characteristic of multi-focus splicing and extending the focal depth, breaks through the contradiction between the numerical aperture and the focal depth of a traditional lens by combining a genetic algorithm, regulates and controls an incident light field through a super-oscillating lens to realize the long-focus deep optical field under the high numerical aperture, and obtains an ultra-long-focus deep super-resolution optical needle light field exceeding the diffraction limit, finally the ultra-long-focus deep super-resolution optical needle light field exceeding the diffraction limit is used for realizing high-depth-to-width ratio laser direct writing processing, and micro-nano structure processing with line width smaller than the diffraction limit and certain requirements on processing depth is realized. The SLM scheme provides a possibility for programmable regulation and control of the optical field, but how to precisely optimize the pupil plane phase through an algorithm under a high Numerical Aperture (NA) objective lens, and generate a plurality of optical focuses with uniform intensity, good side lobe inhibition and high resolution in the axial direction is still a technical problem to be solved. Therefore, it is of great importance to develop an axial multi-focus direct writing method with programmable phase as the core and focusing for high NA objective lens. Disclosure of Invention The invention provides an axial parallel laser direct-writing lithography method with programmable phase regulation, which can generate a plurality of optical focuses with uniform intensity, good side lobe inhibition and high resolution in an axial parallel manner. The invention provides an axial parallel laser direct-writing lithography method with programmable phase regulation, which comprises the follo