Fabrication of Large-Area Silicon Spherical Microlens Arrays by Thermal Reflow and ICP Etching

Fabrication of Large-Area Silicon Spherical Microlens Arrays by Thermal Reflow and ICP Etching

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 surfa...

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Bibliographic Details
Published in:Micromachines (Basel) Vol. 15; no. 4; p. 460
Main Authors: Wu, Yu, Dong, Xianshan, Wang, Xuefang, Xiao, Junfeng, Sun, Quanquan, Shen, Lifeng, Lan, Jie, Shen, Zhenfeng, Xu, Jianfeng, Du, Yuqingyun
Format: Journal Article
Language:English
Published: Switzerland MDPI AG 01-04-2024
Subjects:
Arrays
Electric fields
Etching
etching selectivity
Gas flow
Glass transition temperature
High temperature
ICP etching
Integrated circuit fabrication
Lasers
Light
Machining
microlens array
Microlenses
Photoresists
Plasma etching
Polymers
Process parameters
Silicon
Silicon wafers
Substrates
Surface roughness
Surface tension
thermal reflow process
China
thermal reflow process
etching selectivity
microlens array
ICP etching
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Summary: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 mm 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.
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ISSN:2072-666X
2072-666X
DOI:10.3390/mi15040460