1
|
Wu Y, Dong X, Wang X, Xiao J, Sun Q, Shen L, Lan J, Shen Z, Xu J, Du Y. Fabrication of Large-Area Silicon Spherical Microlens Arrays by Thermal Reflow and ICP Etching. MICROMACHINES 2024; 15:460. [PMID: 38675271 PMCID: PMC11052383 DOI: 10.3390/mi15040460] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/25/2024] [Revised: 03/22/2024] [Accepted: 03/26/2024] [Indexed: 04/28/2024]
Abstract
In this paper, we proposed an efficient and high-precision process for fabricating large-area microlens arrays using thermal reflow combined with ICP etching. When the temperature rises above the glass transition temperature, the polymer cylinder will reflow into a smooth hemisphere due to the surface tension effect. The dimensional differences generated after reflow can be corrected using etching selectivity in the following ICP etching process, which transfers the microstructure on the photoresist to the substrate. The volume variation before and after reflow, as well as the effect of etching selectivity using process parameters, such as RF power and gas flow, were explored. Due to the surface tension effect and the simultaneous molding of all microlens units, machining a 3.84 × 3.84 mm2 silicon microlens array required only 3 min of reflow and 15 min of ICP etching with an extremely low average surface roughness Sa of 1.2 nm.
Collapse
Affiliation(s)
- Yu Wu
- State Key Laboratory of Intelligent Manufacturing Equipment and Technology, School of Mechanical Science and Engineering, Huazhong University of Science and Technology, Wuhan 430074, China; (Y.W.); (J.X.); (Y.D.)
| | - Xianshan Dong
- Science and Technology on Reliability Physics and Application Technology of Electronic Component Laboratory, Guangzhou 511370, China;
| | - Xuefang Wang
- State Key Laboratory of Intelligent Manufacturing Equipment and Technology, School of Mechanical Science and Engineering, Huazhong University of Science and Technology, Wuhan 430074, China; (Y.W.); (J.X.); (Y.D.)
| | - Junfeng Xiao
- State Key Laboratory of Intelligent Manufacturing Equipment and Technology, School of Mechanical Science and Engineering, Huazhong University of Science and Technology, Wuhan 430074, China; (Y.W.); (J.X.); (Y.D.)
| | - Quanquan Sun
- Shanghai Aerospace Control Technology Institute, Shanghai 201109, China (L.S.); (J.L.); (Z.S.)
| | - Lifeng Shen
- Shanghai Aerospace Control Technology Institute, Shanghai 201109, China (L.S.); (J.L.); (Z.S.)
| | - Jie Lan
- Shanghai Aerospace Control Technology Institute, Shanghai 201109, China (L.S.); (J.L.); (Z.S.)
| | - Zhenfeng Shen
- Shanghai Aerospace Control Technology Institute, Shanghai 201109, China (L.S.); (J.L.); (Z.S.)
| | - Jianfeng Xu
- State Key Laboratory of Intelligent Manufacturing Equipment and Technology, School of Mechanical Science and Engineering, Huazhong University of Science and Technology, Wuhan 430074, China; (Y.W.); (J.X.); (Y.D.)
| | - Yuqingyun Du
- State Key Laboratory of Intelligent Manufacturing Equipment and Technology, School of Mechanical Science and Engineering, Huazhong University of Science and Technology, Wuhan 430074, China; (Y.W.); (J.X.); (Y.D.)
| |
Collapse
|
2
|
Wang S, Kong L, Wang C, Cheung C. Ultra-precision manufacturing of microlens arrays using an optimum machining process chain. OPTICS EXPRESS 2023; 31:2234-2247. [PMID: 36785241 DOI: 10.1364/oe.479696] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/03/2022] [Accepted: 11/28/2022] [Indexed: 06/18/2023]
Abstract
There are still significant challenges in the accurate and uniform manufacturing of microlens arrays (MLAs) with advanced ultra-precision diamond cutting technologies due to increasingly stringent requirements and shape complexity. In this paper, an optimum machining process chain is proposed based on the integration of a micro-abrasive fluid jet polishing (MAFJP) process to improve the machining quality by single point diamond turning (SPDT). The MLAs were first machined and compensated by SPDT until the maximum possible surface quality was obtained. The MAFJP was used to correct the surface form error and reduce the nonuniformity for each lens. The polishing characterization was analyzed based on the computational fluid dynamics (CFD) method to enhance the polishing efficiency. To better polish the freeform surface, two-step tool path generation using a regional adaptive path and a raster and cross path was employed. Moreover, the compensation error map was also investigated by revealing the relationship between the material removal mechanism and the surface curvature and polishing parameters. A series of experiments were conducted to prove the reliability and capability of the proposed method. The results indicate that the two integrated machining processes are capable of improving the surface form accuracy with a decrease in PV value from 1.67 µm to 0.56 µm and also elimination of the nonuniform surface error for the lenses.
Collapse
|
3
|
Fabrication of High Precision Silicon Spherical Microlens Arrays by Hot Embossing Process. MICROMACHINES 2022; 13:mi13060899. [PMID: 35744513 PMCID: PMC9228423 DOI: 10.3390/mi13060899] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/06/2022] [Revised: 05/24/2022] [Accepted: 05/27/2022] [Indexed: 11/17/2022]
Abstract
In this paper, a high-precision, low-cost, batch processing nanoimprint method is proposed to process a spherical microlens array (MLA). The nanoimprint mold with high surface precision and low surface roughness was fabricated by single-point diamond turning. The anti-sticking treatment of the mold was carried out by perfluorooctyl phosphoric acid (PFOPA) liquid deposition. Through the orthogonal experiment of hot embossing with the treated mold and subsequent inductively coupled plasma (ICP) etching, the microstructure of MLA was transferred to the silicon substrate, with a root mean square error of 17.7 nm and a roughness of 12.1 nm Sa. The average fitted radius of the microlens array units is 406.145 µm, which is 1.54% different from the design radius.
Collapse
|
4
|
Fundamental Investigation of Diamond Cutting of Micro V-Shaped Grooves on a Polycrystalline Soft-Brittle Material. JOURNAL OF MANUFACTURING AND MATERIALS PROCESSING 2021. [DOI: 10.3390/jmmp5010017] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Fabricating micro-structures on optical materials has received great interest in recent years. In this work, micro-grooving experiments were performed on polycrystalline zinc selenide (ZnSe) to investigate the feasibility of surface micro-structuring on polycrystalline soft-brittle material by diamond turning. A photosensitive resin was coated on the workpiece before cutting, and it was found that the coating was effective in suppressing brittle fractures at the edges of the grooves. The effect of tool feed rate in groove depth direction was examined. Results showed that the defect morphology on the groove surface was affected by the tool feed rate. The crystallographic orientation of grains around the groove was characterized by electron backscatter diffraction (EBSD), and it was found that the formation of defects was strongly dependent on the angle of groove surface with respect to the cleavage plane of grain. The stress distribution of the micro-grooving process was investigated by the finite element method. Results showed that the location of tensile stresses in the coated workpiece was farther from the edge of the groove compared with that in the uncoated workpiece, verifying the experimental result that brittle fractures were suppressed by the resin coating.
Collapse
|
5
|
Lee GJ, Kim HM, Song YM. Design and Fabrication of Microscale, Thin-Film Silicon Solid Immersion Lenses for Mid-Infrared Application. MICROMACHINES 2020; 11:mi11030250. [PMID: 32120857 PMCID: PMC7143082 DOI: 10.3390/mi11030250] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/30/2019] [Revised: 02/24/2020] [Accepted: 02/26/2020] [Indexed: 11/30/2022]
Abstract
Lens-based optical microscopes cannot resolve the sub-wavelength objects overpass diffraction limit. Recently, research on super-resolution imaging has been conducted to overcome this limitation in visible wavelength using solid immersion lenses. However, IR imaging, which is useful for chemical imaging, bio-imaging, and thermal imaging, has not been studied much in optical super-resolution by solid immersion lens owing to material limitations. Herein, we present the design and fabrication schemes of microscale silicon solid immersion lenses (µ-SIL) based on thin-film geometry for mid-infrared (MIR) applications. Compared with geometrical optics, a rigorous finite-difference time-domain (FDTD) calculation of proposed silicon microlenses at MIR wavelengths shows that the outstanding short focal lengths result in enhanced magnification, which allows resolving objects beyond the diffraction limit. In addition, the theoretical analyses evaluate the influences of various structural parameters, such as radius of curvature (RoC), refractive index, and substrate thickness, in µ-SIL. In particular, the high refractive index of µ-SIL is beneficial to implement the outstanding near-field focusing, which corresponds to a high numerical aperture. On the basis of this theoretical background, novel methods are developed for the fabrication of a printable, thin-film silicon microlens array and its integration with a specimen substrate. From the result, we provide a physical understanding of near-field focusing phenomena and offer a promising tool for super-resolution far-field imaging in the MIR range.
Collapse
|
6
|
Xie S, Wan X, Yang B, Zhang W, Wei X, Zhuang S. Design and Fabrication of Wafer-Level Microlens Array with Moth-Eye Antireflective Nanostructures. NANOMATERIALS (BASEL, SWITZERLAND) 2019; 9:E747. [PMID: 31096627 PMCID: PMC6567065 DOI: 10.3390/nano9050747] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/12/2019] [Revised: 05/09/2019] [Accepted: 05/10/2019] [Indexed: 11/26/2022]
Abstract
Wafer-level packaging (WLP) based camera module production has attracted widespread industrial interest because it offers high production efficiency and compact modules. However, suppressing the surface Fresnel reflection losses is challenging for wafer-level microlens arrays. Traditional dielectric antireflection (AR) coatings can cause wafer warpage and coating fractures during wafer lens coating and reflow. In this paper, we present the fabrication of a multiscale functional structure-based wafer-level lens array incorporating moth-eye nanostructures for AR effects, hundred-micrometer-level aspherical lenses for camera imaging, and a wafer-level substrate for wafer assembly. The proposed fabrication process includes manufacturing a wafer lens array metal mold using ultraprecise machining, chemically generating a nanopore array layer, and replicating the multiscale wafer lens array using ultraviolet nanoimprint lithography. A 50-mm-diameter wafer lens array is fabricated containing 437 accurate aspherical microlenses with diameters of 1.0 mm; each lens surface possesses nanostructures with an average period of ~120 nm. The microlens quality is sufficient for imaging in terms of profile accuracy and roughness. Compared to lenses without AR nanostructures, the transmittance of the fabricated multiscale lens is increased by ~3% under wavelengths of 400-750 nm. This research provides a foundation for the high-throughput and low-cost industrial application of wafer-level arrays with AR nanostructures.
Collapse
Affiliation(s)
- Shuping Xie
- Engineering Research Center of Optical Instrument and System, The Ministry of Education, University of Shanghai for Science and Technology, Shanghai 200093, China.
- Ministry of Education and Shanghai Key Laboratory of Modern Optical System, University of Shanghai for Science and Technology, Shanghai 200093, China.
| | - Xinjun Wan
- Engineering Research Center of Optical Instrument and System, The Ministry of Education, University of Shanghai for Science and Technology, Shanghai 200093, China.
- Ministry of Education and Shanghai Key Laboratory of Modern Optical System, University of Shanghai for Science and Technology, Shanghai 200093, China.
| | - Bo Yang
- Engineering Research Center of Optical Instrument and System, The Ministry of Education, University of Shanghai for Science and Technology, Shanghai 200093, China.
- Ministry of Education and Shanghai Key Laboratory of Modern Optical System, University of Shanghai for Science and Technology, Shanghai 200093, China.
| | - Wei Zhang
- Engineering Research Center of Optical Instrument and System, The Ministry of Education, University of Shanghai for Science and Technology, Shanghai 200093, China.
- Ministry of Education and Shanghai Key Laboratory of Modern Optical System, University of Shanghai for Science and Technology, Shanghai 200093, China.
| | - Xiaoxiao Wei
- Engineering Research Center of Optical Instrument and System, The Ministry of Education, University of Shanghai for Science and Technology, Shanghai 200093, China.
- Ministry of Education and Shanghai Key Laboratory of Modern Optical System, University of Shanghai for Science and Technology, Shanghai 200093, China.
| | - Songlin Zhuang
- Engineering Research Center of Optical Instrument and System, The Ministry of Education, University of Shanghai for Science and Technology, Shanghai 200093, China.
- Ministry of Education and Shanghai Key Laboratory of Modern Optical System, University of Shanghai for Science and Technology, Shanghai 200093, China.
| |
Collapse
|
7
|
Fabrication of Multiscale-Structure Wafer-Level Microlens Array Mold. APPLIED SCIENCES-BASEL 2019. [DOI: 10.3390/app9030487] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
The design and manufacture of cost-effective miniaturized optics at wafer level, usingadvanced semiconductor-like techniques, enables the production of reduced form-factor cameramodules for optical devices. However, suppressing the Fresnel reflection of wafer-level microlensesis a major challenge. Moth-eye nanostructures not only satisfy the antireflection requirementof microlens arrays, but also overcome the problem of coating fracture. This novel fabricationprocess, based on a precision wafer-level microlens array mold, is designed to meet the demandfor small form factors, high resolution, and cost effectiveness. In this study, three different kinds ofaluminum material, namely 6061-T6 aluminum alloy, high-purity polycrystalline aluminum, and purenanocrystalline aluminum were used to fabricate microlens array molds with uniform nanostructures.Of these three materials, the pure nanocrystalline aluminum microlens array mold exhibited auniform nanostructure and met the optical requirements. This study lays a solid foundation for theindustrial acceptation of novel and functional multiscale-structure wafer-level microlens arrays andprovides a practical method for the low-cost manufacture of large, high-quality wafer-level molds.
Collapse
|