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Printing of thick resist patterns with a high aspect ratio and vertical side walls was investigated. Such resist
patterns are required for using as molds of electroplating, and patterning feasibility in a small field of 2 mm square
was verified in the past researches. However, it is necessary to print patterns homogeneously in an exposure field
with a practical size of larger than 10 mm square, for example. As profiles of resist patterns for the use of
electroplating molds, rectangular cross-sections are preferable. For this reason, patterns were printed in the
negative resist SU-8 with a thickness of 50 μm using an exposure system with a field size of 15 mm square. Before
using the thick SU-8, the best focus position of the exposure system was investigated. To find out the best focus
position, line and space (LS) patterns were printed using a positive resist OFPR-800 with a thickness of
approximately 1 μm. The focus position where patterns were most clearly formed on the wafer was decided to be
the focus origin, and defocuses were controlled by moving wafers downward. Next, 50-μm LS patterns were
printed in 50-μm thick SU-8. As a result, LS patterns with rectangular cross sections and a height of 40 μm were
obtained when the defocus and the exposure time were set at 2000 μm and for 70 seconds, respectively. It was
demonstrated that patterns with rectangular cross sections were printed in 3x5 mm2 exposure fields.
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