Photolithography system with liquid crystal display as active gray-tone mask for 3D structuring of photoresist

Hayashi, Terutake; Shibata, Takayuki; Kawashima, Takahiro; Makino, Eiji; Matsukawa, Takashi; Masuzawa, Toru

doi:10.1016/j.sna.2008.02.014

Cited by 31 publications

(14 citation statements)

References 19 publications

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“…Similar exposure systems were also proposed by other research groups [8][9][10][11][12][13]. On the other hand, many researches on exposure systems using digital micromirror devices (DMDs) instead of LCD panels were also reported [14][15][16][17][18][19].…”

Section: Introductionsupporting

confidence: 62%

Simple maskless lithography tool with a desk-top size using a liquid-crystal-display projector

Horiuchi

Koyama

Kobayashi

2015

Microelectronic Engineering

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Section: Introductionsupporting

confidence: 62%

Simple maskless lithography tool with a desk-top size using a liquid-crystal-display projector

Horiuchi

Koyama

Kobayashi

2015

Microelectronic Engineering

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“…Therefore, maskless lithography systems are preferred, and various exposure systems using liquid-crystal-display (LCD) panels in place of reticles have been proposed [1][2][3][4][5][6][7]. The authors also developed several systems in the past researches [8][9][10][11][12][13][14], and recently, proposed a very low-cost exposure system using a commercial LCD projector as it was [15].…”

Section: Introductionmentioning

confidence: 99%

Pattern Width Homogenization in the Field of Liquid-Crystal-Display Matrix Exposure by Adjusting Each Cell Transmittance

Horiuchi

Haneishi

Yoshida

et al. 2016

J. Photopol. Sci. Technol.

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Width homogenization of patterns printed by the desktop matrix-exposure system using a commercial liquid-crystal-display projector was investigated. At first, it was thought that the pattern width distribution caused by the dispersion of illumination-light intensity would be easily compensated by adjusting each bright cell transmittance. However, it was fundamentally difficult. Bottom peaks of the image intensity did not reach zero caused by the diffraction and intrinsic transmittance of black cells. For this reason, the bottom peaks also distributed depending on the illumination-light intensity. As a result, image contrast was degraded by reducing the transmittance of bright cells. To print line-and-space (L&S) patterns homogeneously in the exposure field, it was also necessary to increase the transmittance of black cells at places where the illumination-light intensity was low. By this countermeasure, down to 2-pixel L&S patterns were printed almost homogeneously. The width distribution of 4-and 5-pixel L&S patterns was suppressed almost within ±10%.

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“…However, the binary mask, which was used in projection photolithography in this technique, imposed the restriction to fabricate the three dimensional (3D) microstructures with continuously changed surfaces, such as microlens structures. To this end, a digital micromirror device (DMD) [10][11][12] or a liquid crystal display (LCD) [13] has been used as a dynamic photomask to fabricate the microlens arrays or 3D microstructures through projection photopolymerization. However, the surface roughness of the microlens arrays is a considerable issue due to the limited resolution (4 μm image pixel size) of the DMD or LCD, which can significantly reduce the optical performance of the microlens arrays.…”

Section: Introductionmentioning

confidence: 99%

Stop-flow Lithography to Continuously Fabricate Microlens Structures Utilizing an Adjustable Three-Dimensional Mask

Huang

Lin

2014

Micromachines

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Stop-flow lithography (SFL) is a microfluidic-based particle synthesis method, in which photolithography with a two dimensional (2D) photomask is performed in situ within a microfluidic environment to fabricate multifunctional microstructures. Here, we modified the SFL technique by utilizing an adjustable electrostatic-force-modulated 3D (EFM-3D) mask to continuously fabricate microlens structures for high-throughput production. The adjustable EFM-3D mask contains a layer filled with a UV-absorbing liquid and transparent elastomer structures in the shape of microlenses between two conductive glass substrates. An acrylate oligomer stream is photopolymerized via the microscope projection photolithography, where the EFM-3D mask was set at the field-stop plane of the microscope, thus forming the microlens structures. The produced microlens structures flow downstream without adhesion to the polydimethysiloxane (PDMS) microchannel surfaces due to the existence of an oxygen-aided inhibition layer. Microlens structures with variations in curvature and aperture can be produced by changing objective magnifications, controlling the morphology of the EFM-3D mask through electrostatic force, and varying the concentration of UV-light absorption dyes. We have successfully demonstrated to produce microlens structures with an aperture ranging from 50 μm to 2 mm and the smallest focus spot size of 0.59 μm. Our proposed method allows one to fabricate microlens structures in a fast, simple and high-throughput mode for application in micro-optical systems. OPEN ACCESSMicromachines 2014, 5 668

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Photolithography system with liquid crystal display as active gray-tone mask for 3D structuring of photoresist

Cited by 31 publications

References 19 publications

Simple maskless lithography tool with a desk-top size using a liquid-crystal-display projector

Simple maskless lithography tool with a desk-top size using a liquid-crystal-display projector

Pattern Width Homogenization in the Field of Liquid-Crystal-Display Matrix Exposure by Adjusting Each Cell Transmittance

Stop-flow Lithography to Continuously Fabricate Microlens Structures Utilizing an Adjustable Three-Dimensional Mask

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