Effect of Near-Field Diffraction in Photolithography of Hexagonal Arrays for Dichroic Filters
Dichroic filters with the hexagonal lattice of circular holes are used as fundamental devices for frequency selection from the infrared to the terahertz (THz) region. In the fabrication of such a high-density periodic array by the contact-mode photolithography, the depth of focus (DOF) turns out to...
| Main Authors: | , , , , |
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| Format: | Article |
| Language: | English |
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IEEE
2016-01-01
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| Series: | IEEE Photonics Journal |
| Subjects: | |
| Online Access: | https://ieeexplore.ieee.org/document/7536185/ |
| _version_ | 1819121011385171968 |
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| author | Shaolin Zhou Junbo Liu Qian Deng Changqing Xie Mansun Chan |
| author_facet | Shaolin Zhou Junbo Liu Qian Deng Changqing Xie Mansun Chan |
| author_sort | Shaolin Zhou |
| collection | DOAJ |
| description | Dichroic filters with the hexagonal lattice of circular holes are used as fundamental devices for frequency selection from the infrared to the terahertz (THz) region. In the fabrication of such a high-density periodic array by the contact-mode photolithography, the depth of focus (DOF) turns out to be tremendously shrunk for ideal pattern contrast. In this paper, near-field diffraction of the hexagonal lattice was analytically treated, and the tolerant DOF was estimated in terms of the Talbot distance in photolithography. Affine transformation was applied to the rectangular lattice to derive the near-field diffraction intensity, and a process factor k<sub>2</sub> was introduced to predetermine the practical DOF in photolithography. Numerical calculations according to the analytic predication agree well with the preliminary experiments, where the intensity evolved drastically to suppress the limited DOF zone. It was also revealed that the practical DOF can be improved by eliminating the high-order diffraction or using the photoresist with higher threshold energy to enhance the process factor. The analytic and experimental results can be used to optimize the high-contrast patterning by optical lithography. |
| first_indexed | 2024-12-22T06:29:46Z |
| format | Article |
| id | doaj.art-73edaa64c6d64796a98f85ef474e328a |
| institution | Directory Open Access Journal |
| issn | 1943-0655 |
| language | English |
| last_indexed | 2024-12-22T06:29:46Z |
| publishDate | 2016-01-01 |
| publisher | IEEE |
| record_format | Article |
| series | IEEE Photonics Journal |
| spelling | doaj.art-73edaa64c6d64796a98f85ef474e328a2022-12-21T18:35:45ZengIEEEIEEE Photonics Journal1943-06552016-01-018411110.1109/JPHOT.2016.25940327536185Effect of Near-Field Diffraction in Photolithography of Hexagonal Arrays for Dichroic FiltersShaolin Zhou0Junbo Liu1Qian Deng2Changqing Xie3https://orcid.org/0000-0002-8697-3860Mansun Chan4School of Electronics and Information Engineering, South China University of Technology, Guangzhou, ChinaState Key Laboratory of Optical Technologies for Microfabrication, Institute of Optics and Electronics, Chinese Academy of Sciences, Chengdu, ChinaState Key Laboratory of Optical Technologies for Microfabrication, Institute of Optics and Electronics, Chinese Academy of Sciences, Chengdu, ChinaKey Laboratory of Microelectronics Devices and Integrated Technology, Institute of Microelectronics, Chinese Academy of Sciences, Beijing, ChinaDepartment of Electronics and Computer Engineering, Hong Kong University of Science and Technology, Kowloon, Hong KongDichroic filters with the hexagonal lattice of circular holes are used as fundamental devices for frequency selection from the infrared to the terahertz (THz) region. In the fabrication of such a high-density periodic array by the contact-mode photolithography, the depth of focus (DOF) turns out to be tremendously shrunk for ideal pattern contrast. In this paper, near-field diffraction of the hexagonal lattice was analytically treated, and the tolerant DOF was estimated in terms of the Talbot distance in photolithography. Affine transformation was applied to the rectangular lattice to derive the near-field diffraction intensity, and a process factor k<sub>2</sub> was introduced to predetermine the practical DOF in photolithography. Numerical calculations according to the analytic predication agree well with the preliminary experiments, where the intensity evolved drastically to suppress the limited DOF zone. It was also revealed that the practical DOF can be improved by eliminating the high-order diffraction or using the photoresist with higher threshold energy to enhance the process factor. The analytic and experimental results can be used to optimize the high-contrast patterning by optical lithography.https://ieeexplore.ieee.org/document/7536185/Diffractionphotolithographyterahertz filtershexagonal array |
| spellingShingle | Shaolin Zhou Junbo Liu Qian Deng Changqing Xie Mansun Chan Effect of Near-Field Diffraction in Photolithography of Hexagonal Arrays for Dichroic Filters IEEE Photonics Journal Diffraction photolithography terahertz filters hexagonal array |
| title | Effect of Near-Field Diffraction in Photolithography of Hexagonal Arrays for Dichroic Filters |
| title_full | Effect of Near-Field Diffraction in Photolithography of Hexagonal Arrays for Dichroic Filters |
| title_fullStr | Effect of Near-Field Diffraction in Photolithography of Hexagonal Arrays for Dichroic Filters |
| title_full_unstemmed | Effect of Near-Field Diffraction in Photolithography of Hexagonal Arrays for Dichroic Filters |
| title_short | Effect of Near-Field Diffraction in Photolithography of Hexagonal Arrays for Dichroic Filters |
| title_sort | effect of near field diffraction in photolithography of hexagonal arrays for dichroic filters |
| topic | Diffraction photolithography terahertz filters hexagonal array |
| url | https://ieeexplore.ieee.org/document/7536185/ |
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