CN-121578592-B - Multi-stage fine alignment method for complex micro-nano structure

CN121578592BCN 121578592 BCN121578592 BCN 121578592BCN-121578592-B

Abstract

A multistage fine alignment method for a complex micro-nano structure belongs to the technical field of micro-nano processing. The multistage fine alignment method comprises the steps of firstly forming a patterned mask with an accurate undercut contour by optimizing the thickness of an upper photoresist layer, a lower photoresist layer, spin coating parameters and two independent developing processes based on a double-layer photoresist system, then performing layer-by-layer alignment in an alignment precision range of 800nm to 3 mu m through a global alignment mark group preset in a mask mold, and finally combining magnetron sputtering and an accurate stripping process to realize residue-free transfer of high-precision metal or dielectric film patterns and sequentially completing preparation of a multilayer micro-nano composite structure. The invention can simplify the process flow, enhance the process compatibility, reduce the equipment investment and the manufacturing cost while ensuring the high-precision integrated manufacturing, provides a reliable technical path for the batch manufacturing of complex micro-nano devices, and has wide application prospect in the fields of integrated optics, MEMS, multifunctional sensors and the like.

Inventors

LIAN MENG
JIA JINGYUAN
SU YING
ZHANG MINGQI
Cao tun
ZHENG CHUANG
LIU JIAN
ZHANG LEI
CHEN ZIJIAN
LIU KUAN
CAO GAOFENG

Assignees

大连理工大学

Dates

Publication Date: 20260505
Application Date: 20260127

Claims (7)

1. The multi-stage fine alignment method for the complex micro-nano structure is characterized by comprising the following steps of: The first step is to pretreat the substrate to remove tiny particles and oxides on the surface of the substrate, so as to enhance the adhesive force between the photoresist and the substrate; The second step, spin coating two positive photoresist with different sensitivities on the surface of the substrate to obtain a double-layer photoresist film structure, wherein the following specific steps are that: Firstly removing water vapor on the surface of a substrate, then determining the thickness of positive photoresist based on the required thickness of a material film by a spin coating method, selecting spin coating parameters, spin coating two positive photoresists with different sensitivities, spin coating positive photoresist with high sensitivity, and spin coating positive photoresist with low sensitivity to obtain a double-layer photoresist film structure; thirdly, carrying out mask exposure on the double-layer glue film structure formed in the second step; And fourthly, double developing the exposed double-layer photoresist film structure, wherein the high-sensitivity photoresist is wider than the low-sensitivity photoresist developing structure in the developing process, so as to form the film structure with an undercut structure, and the method comprises the following steps: Step 4.1, performing first development on the exposed double-layer adhesive film structure, completely soaking the double-layer adhesive film structure in a developing solution for 2-4 seconds, flushing with deionized water after development, and drying with nitrogen to form an incompletely developed double-layer adhesive film structure; Step 4.2, carrying out secondary development on the double-layer adhesive film structure which is not completely developed, completely soaking the double-layer adhesive film structure which is not completely developed in a developing solution for 2-4 seconds, flushing with deionized water after development, and drying with nitrogen to obtain an adhesive film structure with an undercut structure; Depositing a material film on the adhesive film structure with the undercut structure; Stripping the deposited material film to remove redundant positive photoresist and the material film to obtain a first layer structure; Obtaining a first layer structure of the micro-nano structure through the preparation process from the first step to the sixth step; And seventhly, according to the number of layers of the micro-nano structure, taking the first layer structure as a new substrate, repeating the first step to the sixth step, and sequentially preparing each layer structure of the micro-nano structure to realize multi-stage complex micro-nano structure integration.
2. The multi-stage fine alignment method for a complex micro-nano structure according to claim 1, wherein the first step specifically comprises: Pretreating a substrate by adopting a chemical corrosion method, ultrasonically cleaning the substrate by using acetone in an ultra-clean room, wherein the ultrasonic time is 10-30 minutes, the ultrasonic power is 70W, then soaking the substrate by using isopropanol for 5-10 minutes, and then showering the substrate by using deionized water for 5-10 minutes, and finally drying the substrate by using nitrogen; The substrate is monocrystalline silicon, silicon nitride or gallium nitride.
3. The multi-stage fine alignment method for a complex micro-nano structure according to claim 2, wherein the second step specifically comprises: 2.1, baking the substrate to remove water vapor on the surface of the substrate, so that the surface of the substrate is changed from hydrophilicity to hydrophobicity, wherein the baking temperature is 180-200 ℃, and the baking time is 3-5 minutes; Step 2.2, determining spin parameters; Determining positive photoresist with corresponding thickness according to a formula (1) by a spin coating method according to the required thickness of a material film, and selecting spin parameters, wherein the spin parameters comprise spin time and rotating speed, the spin time is set to be 30-40 seconds, and the rotating speed is set to be 2500-4000 rpm; (1) Wherein H PR is the total positive photoresist thickness, H Film is the required thickness of the material film, K is the safety coefficient, and the value is 1.5-2; Step 2.3, spin-coating two positive photoresists with different sensitivities according to the spin-coating parameters selected in the step 2.2, spin-coating positive photoresists with high sensitivity to form base photoresist, and spin-coating positive photoresists with low sensitivity to form top photoresist, wherein the ratio of the thickness of the base photoresist to the thickness of the top photoresist is 1.25:1; and 2.4, baking the double-layer adhesive film structure, wherein the baking temperature is 90-150 ℃ and the baking time is 2-5 minutes.
4. The multi-stage fine alignment method for a complex micro-nano structure according to claim 3, wherein the third step specifically comprises: Step 3.1, when designing a mask plate layout, planning a set of global alignment mark groups formed by high-contrast cross line structures in the peripheral area of a non-functional area; step 3.2, exposing the double-layer glue film structure by using a photoetching system; the photoetching system comprises a high-magnification binocular microscope system, ultraviolet light is adopted for exposure, the exposure dose range is determined according to the recommended value of the photoresist data table, and the exposure time is calculated through a formula (2); (2) Where T is the exposure time, E best is the exposure dose, and P is the exposure power density.
5. The multi-stage fine alignment method for a complex micro-nano structure according to claim 4, wherein in the third step: In the step 3.1, the mask plate layout comprises a nonfunctional area and a functional area, wherein functional graphic structures for defining the geometric shape and the size of the micro-nano composite structure are distributed on the functional area, and other areas outside the functional area are nonfunctional areas, including the periphery and the gap area of the mask plate layout; In the step 3.2, the lithography system is capable of fine tuning x, y, The shaft is aligned accurately, the alignment precision range reaches 800nm to 3 mu m, the wavelength of ultraviolet light is 350 nm-400 nm, and the exposure power is 450W.
6. The method for multistage fine alignment of a complex micro-nano structure according to claim 5, wherein in the fifth step, a magnetron sputtering device is used to sputter a material film on the surface of the film structure with an undercut structure, and the sputtering rate is calculated by the formula (3); (3) Wherein V is the sputtering rate of the target material under unit power, P is the sputtering power of the target material, t is the sputtering time, d is the thickness of the material film, Is the element content in the material film.
7. The multi-stage fine alignment method for the complex micro-nano structure according to claim 6, wherein the sixth step comprises the steps of selecting an acetone solution to soak the sputtered substrate for 3-12 hours, wiping off excessive photoresist and film by using absorbent cotton, soaking in isopropanol for 5-10 minutes, finally showering in deionized water for 2-3 minutes, and drying by using nitrogen to obtain the first layer structure.

Description

Multi-stage fine alignment method for complex micro-nano structure Technical Field The invention belongs to the technical field of micro-nano processing, and relates to a multi-stage fine alignment method for a complex micro-nano structure. Background The complex micro-nano structure is a core for realizing advanced devices such as next-generation integrated photon chips, high-end MEMS sensors and the like, and provides brand new device architecture and performance breakthrough possibility for the fields of information technology, biomedical treatment and the like. The manufacturing process for constructing the complex micro-nano structures, namely the multilayer overlay and patterning technology, is a key for realizing the function integration and the performance optimization of the device. The multilayer overlay technology needs to have extremely high interlayer alignment precision and complete pattern transfer fidelity, and meanwhile, as the process flow needs to undergo multiple cycles, the process itself needs to have excellent stability and compatibility, so that the yield and reliability of the final device are ensured. In addition to structural complexity, the number of layers to be etched and the quality of each layer of pattern directly affect the functional density and upper performance limit of the overall device. At present, the micro-nano structure is manufactured by adopting a step-by-step processing strategy, namely, different processing equipment and processing methods are switched in the preparation process of structures with different scales. In 2013, chen Anlu et al succeeded in preparing a device with good electrical characteristics and a minimum grating length of 26 nm by adopting a matching hybrid lithography technology of an electron beam direct writing and an optical exposure system in paper 'electron beam and optical hybrid lithography technology for nano devices', and in 2025, li Xinghui et al at the university of Qinghua constructed an interference exposure system capable of being adjusted in multiple degrees of freedom in paper 'Cross-Scale Structures Fabrication via Hybrid Lithography for Nanolevel Positioning', integrated a double-beam interference exposure and high-precision stripe locking system, and realized high-consistency pattern processing in a region through dynamic phase locking. In 2025, you Zheng et al in the university of Qinghua, in chinese patent No. CN120089612a, disclose a method and apparatus for monitoring a process of dry etching of a plasma based on a super-structured surface, wherein a critical structure is extracted from a lithography layout of a target device and periodically arranged to form the super-structured surface, and then the super-structured surface is spliced with an original pattern to perform etching, so that excessive etching or insufficient etching is avoided, and thus process controllability and device yield are improved. The multi-process combination mode realizes cross-scale processing to a certain extent, but also brings a series of problems that firstly, the conversion among different processes needs multiple times of clamping, alignment and condition adjustment, so that the process flow is complex, the period is prolonged, the cost is increased, secondly, the systematic errors and overlay deviation among multiple devices are difficult to effectively control, the alignment precision and interface quality of an interlayer structure are influenced, and in addition, the requirements of different processes on material characteristics and surface states possibly conflict, and the process compatibility and the structure reliability are reduced. Therefore, a manufacturing method capable of realizing multi-level micro-nano alignment by a set of molding process scheme is needed to simplify the flow, improve the precision, enhance the compatibility and promote the further development of the multi-layer micro-nano structure in practical application. Disclosure of Invention The invention mainly solves the technical problem of overcoming the limitation of the existing micro-nano processing technology. Aiming at the problems that the current multilayer overlay technology is limited by the problems of poor stripping effect of single-layer photoresist, large overlay accuracy accumulation error and the like, and can only realize the processing of a 2-3-layer structure, a multi-stage fine overlay method for a complex micro-nano structure is provided. The invention forms the patterned mask with controllable undercut structure by introducing a double-layer photoresist system and a double-development process, effectively solves the problem of film residue in multilayer processing, and simultaneously adopts the design of a global alignment mark group to remarkably improve interlayer alignment precision. By combining magnetron sputtering and accurate stripping processes, the preparation of 5-7 layers of micro-nano composite structures can be sequentially co