Matrix Projection Exposure Using an Analogue Liquid Crystal Display Panel in Place of a Reticle |
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Authors: | Toshiyuki Horiuchi Ayaka Otani |
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Institution: | (1) Tokyo Denki University, 2-2 Kanda-Nishiki-cho, Chiyoda-ku, Tokyo 101-8457, Japan;(2) Present address: Seiko Instruments Inc., Japan |
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Abstract: | The most serious problems for the matrix projection exposure using a liquid crystal display (LCD) panel in place of a reticle
are largely solved by a new breakthrough method. LCD matrix exposure is effective for small volume productions of print circuits,
screen masks, micromachine parts, and other items. Since no reticles are needed, all reticle costs are saved, and turnaround
times required for changing the patterns are greatly shortened. However, in the conventional method, pattern widths and positions
were strictly restricted depending on the geometric size and pitch of the liquid crystal cells. In this paper, a new concept
appointing the cell brightness grades continuously using an analogue interface LCD panel is proposed. Calculating the image
intensity distributions for various appointments of cell brightness balances to print same wide patterns, it is clarified
that the pattern widths and positions are not much different if the pattern widths are wider than 2 cell pitches of the LCD
panel. Maximum width and position variations are less than ± 10% even when the patterns are printed at arbitrary positions,
of course including halfway ones. The calculated results are proved by experiments using an analogue LCD panel with a cell
pitch of 15 μm. Though the cell size are 13 × 10 μm2, and different in x and y directions, almost same wide line-and-space patterns are successfully printed at all positions
by only one exposure. It is not necessary to shift the reticle for overlapping exposures to print smooth patterns. Oblique
patterns and complicated Chinese character patterns are also printed at arbitrary positions. The new breakthrough technology
will make the LCD matrix exposure promising for wide uses of printing various rough patterns easily at small costs. |
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Keywords: | projection exposure matrix exposure reticleless exposure analogue LCD panel arbitrary patterning |
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