6 October 2017 Suppression of imaging crack caused by the gap between micromirrors in maskless lithography
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Abstract
The digital micromirror device (DMD) is the key device in maskless lithography. However, because of the machinery manufacturing limit of DMDs, the gap between the micromirrors may destroy the continuity of the graphic. This work presents a simple way to fill the imaging crack by controlling the partial coherence factor σ of the light source. A crack can be regarded as the image of a dark space. By considering the resolving power for such cracks under partially coherent illumination, the images of such dark spaces can be covered, preventing them from being imaged on the substrate. By using mathematical derivations of the light intensity distribution exposed to the substrate, and by utilizing the diffraction effect induced by the finite aperture of the optical projection system, an appropriate σ value can be determined for eliminating the image of the crack in an actual scene. The numerical simulation results demonstrate that this method can ensure the continuity of the graphic at the critical partial coherence factor σc regardless of the shape of the target graphic.
© 2017 Society of Photo-Optical Instrumentation Engineers (SPIE)
Liwen Liang, Liwen Liang, Jinyun Zhou, Jinyun Zhou, Liang Lei, Liang Lei, Bo Wang, Bo Wang, Qu Wang, Qu Wang, Kunhua Wen, Kunhua Wen, } "Suppression of imaging crack caused by the gap between micromirrors in maskless lithography," Optical Engineering 56(10), 106102 (6 October 2017). https://doi.org/10.1117/1.OE.56.10.106102 . Submission: Received: 20 June 2017; Accepted: 13 September 2017
Received: 20 June 2017; Accepted: 13 September 2017; Published: 6 October 2017
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