Memoirs of the School of Engineering, Nagoya University Vol.50, No.1/2 (1998) MICRO FABRICATION BY UV LASER PHOTOPOLYMERIZATION Katsumi YAMAGUCHI and Takeshi NAKAMOTO Department of Mechanical Engineering (Received November 4, 1998

This research deals with the development of simple and practical methods for
manufacturing high aspect ratio (height/width) micro parts and three-dimensional
micro parts. The first method is mask-based method in which an image is transferred
to a liquid photopolymer by irradiating a UV laser through a patterned mask.
The irradiated portion of the photopolymer is then solidified and it becomes
a high aspect ratio polymer structure or mold. In the second and third methods,
high aspect ratio polymer structures are produced using a shaped UV laser beam
writing and a focused UV laser beam writing, respectively.
The desired product shape is obtained by writing along the contour of the product
on the surface of a liquid photopolymer. The written pattern then becomes solid so
as to produce a solidified polymer structure or mold. The fourth, three-dimensional
micro part is produced by a focused UV laser beam writing method.
The accuracy of the solidified polymer when using these methods is examined.
The examination is done theoretically and experimentally.
The optimum conditions to produce high aspect ratio micro parts and three-dimensional
micro parts are also verified.
Various shapes of micro polymer structures are produced using these methods.

Keywords: Micro fabrication, Photopolymer, UV laser, High aspect ratio micro part,
Three-dimensional micro part, Accuracy, Mask-based method, Beam writing method,
Diffraction of light, Absorption of light, Solidification