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Proceedings Paper

Impact of the back side flatness of a mask on the panel overlay
Author(s): Daisuke Kemmochi; Yutaka Yoshikawa; Yoshinori Iwanaga; Termusa Hirano; Hiroshi Kinoshita
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Paper Abstract

Recently, the annual increase in the definition of high-function panels for mobile devices such as smartphones or tablets has led to TFT-LCD and TFT-OLED (Organic Light Emitting Diode) circuits becoming increasingly miniaturized and densified. TFT circuits are comprised of a superposition of layers such as gates, acts and contact holes, with a certain amount of allowance between each layer. However, that allowance has now disappeared due to the high density of the circuit. Therefore, a high-precision mask overlay is essential in order to realize circuits with even higher density. In the mask manufacturing process, the mask is placed on a writer tool, during which the back side surface of the mask makes contact with the stage. This contact alters the front side flatness of the mask. Moreover, once the circuit pattern has been drawn on the mask, it is removed from the writer tool, thus altering the front side flatness and coordinates of the mask. In this paper, we evaluated the overlay of a panel that underwent exposure using a number of masks with different back side flatness. As a result, we confirmed that deviations in the back side flatness of each mask manifest themselves in the panel overlay. Therefore, we need to improve the flatness of the back side of masks hereafter in order to further enhance the panel overlay.

Paper Details

Date Published: 9 July 2015
PDF: 6 pages
Proc. SPIE 9658, Photomask Japan 2015: Photomask and Next-Generation Lithography Mask Technology XXII, 965803 (9 July 2015); doi: 10.1117/12.2196074
Show Author Affiliations
Daisuke Kemmochi, HOYA Corp. (Japan)
Yutaka Yoshikawa, HOYA Corp. (Japan)
Yoshinori Iwanaga, HOYA Corp. (Japan)
Termusa Hirano, HOYA Corp. (Japan)
Hiroshi Kinoshita, HOYA Corp. (Japan)

Published in SPIE Proceedings Vol. 9658:
Photomask Japan 2015: Photomask and Next-Generation Lithography Mask Technology XXII
Nobuyuki Yoshioka, Editor(s)

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