Microlens array fabrication by backside exposure using Fraunhofer diffraction

Song, In-Hyouk; Kang, Kyungnam; Jin, Yoonyoung; Park, Daniel S.-W.; Ajmera, Pratul K.

doi:10.1007/s00542-007-0510-2

Cited by 11 publications

(8 citation statements)

References 6 publications

(5 reference statements)

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“…The cause for this not clear but appears to be related to the dose. Similar effects have also been observed by others (Song et al 2007b). The shape and size of micro-nozzles depend on dosage, aperture size, zone plate size, distance between the mask, the resist and exposure wavelength.…”

Section: Discussionsupporting

confidence: 70%

Shape controllable micro-nozzle fabrication

et al. 2008

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A novel fabrication method involving two-step sequential backside exposures utilizing Fraunhofer diffraction is developed in this work to overcome some of the limitations of the current micro-nozzle fabrication techniques in controlling the shape and the size of micronozzles. Shape and size of the fabricated micro-nozzles are compared with simulation results. Micro-nozzles with tip diameters varying from 0 to 158.1 lm and the base diameter varying from 167.2 to 360 lm are fabricated simultaneously side-by-side on the same substrate by varying the total exposure dosage from 3 to 6 J/cm 2 utilizing multiple backside exposures through designed circular aperture and zone plate masks.

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Section: Discussionsupporting

confidence: 70%

Shape controllable micro-nozzle fabrication

et al. 2008

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“…This approach to beam deflection, at the microscopic scale, is similar to previous work where micro-optical elements have been mounted onto finished laser arrays [9,10,11], but we are not aware of a greyscale fabrication method being employed to integrate micro-elements directly onto the device. Integration of micro-optic elements has been achieved before but has involved alternate fabrication techniques, further to the device construction [12,13].…”

Section: Introductionmentioning

confidence: 77%

Integrated polymer microprisms for free space optical beam deflecting

Reardon¹,

Falco²,

Welna³

et al. 2009

Opt. Express

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Abstract:We demonstrate beam deflection and multiple channel communication in free space optical communications using microprisms integrated directly onto an array of vertical cavity surface emitting lasers (VCSELs). The design and fabrication of such a transmitter is presented, and shown to achieve beam deflection of up to 10° in a planar configuration. A location discovery application, for use within a distributed network, is put forward and analysed.

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“…Since near-UV light (wavelength: 350-400 nm) is the optimum source for use with SU-8 photoresist and synchrotron radiation is very expensive and not widely available, UV light has been developed to supersede synchrotron radiation in lithography applications. In recent years, SU-8 photoresist has been applied to various systems such as lab-on-chip devices [2][3][4], optical devices [5][6][7][8][9] and drug delivery systems [10].…”

Section: Introductionmentioning

confidence: 99%

“…The attenuation of the light intensity generates microstructure with a larger head and a smaller bottom (the so-called 'big head effect') [12,13,15,16,19] in conventional proximity lithography. In order to overcome the big head effect, researchers have developed many lithography techniques such as backside exposure lithography [9,10,16,[20][21][22][23][24][25][26], reflection lithography [15,19], h-line and g-line lithography [14,18] and a lithography technique in which the gap between the photomask and the photoresist is filled with glycerol [13]. The use of h-line and g-line sources successfully reduced the attenuation of the light intensity and the diffraction effect, but the microstructure profile was not controlled.…”

Section: Introductionmentioning

confidence: 99%

Study on diffraction effect and microstructure profile fabricated by one-step backside lithography

Yang¹,

Huang²,

Shew³

et al. 2013

J. Micromech. Microeng.

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Backside exposure lithography has been proven to be able to generate needle-like microstructures. The structure profile can be controlled by varying the aperture diameter on the photomask and the distance between the photomask and the photoresist. This distance is usually defined by the glass thickness of the glass in backside exposure lithography. However, in our experience, needle-like structures can be generated easily in some cases but not in others. In order to accurately predict the microstructure profile fabricated by backside exposure lithography, in this study, we built a complete three-dimensional Fresnel–Kirchhoff diffraction model and used a binary approach to simulate the curing threshold. We found that the microstructure profile is influenced by diffraction in both the near-field (Fresnel) and far-field regions (Fraunhofer). Diffraction depends on the design pattern on the photomask and the glass thickness. In many cases, it changes gradually from the near-field to the far-field. This is exactly the reason that our approach generates needle-like structures. Structures ranging from 50 to 450 µm in height were simulated by our model and had a high degree of consistency with the fabricated results. This research may provide potential guidelines for the prediction and the fabrication of needle-like structures for future applications.

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Microlens array fabrication by backside exposure using Fraunhofer diffraction

Cited by 11 publications

References 6 publications

Shape controllable micro-nozzle fabrication

Shape controllable micro-nozzle fabrication

Integrated polymer microprisms for free space optical beam deflecting

Study on diffraction effect and microstructure profile fabricated by one-step backside lithography

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