Equations of exposure time and X-ray mask absorber thickness in the LIGA process

The LIGA X-ray exposure step was modeled into three inequalities from exposure requirements. From these inequalities, equations for the minimum and maximum exposure times required for a good quality microstructure were obtained. An equation for the thickness of an X-ray mask absorber was also obtained from the exposure requirement of threshold dose deposition. A power function of photon energy, approximating the attenuation length of the representative LIGA resist, PMMA, and the mean photon energy of the X-rays incident upon an X-ray mask absorber were applied to the above mentioned equations. Consequently, the trends of the minimum and maximum exposure times with respect to mean photon energy of X-rays and thickness of PMMA were examined and an equation for the maximum exposable thickness of PMMA was obtained. The trends of the necessary thickness of a gold X-ray mask absorber with respect to photon energy of the X-rays and PMMA thickness ratio were also examined. The simplicity of the derived equations has clarified the X-ray exposure phenomenon and the interplay of exposure times, the attenuation coefficient and the thickness of an X-ray mask absorber, the attenuation coefficient and the thickness of a resist, and synchrotron radiation power density.
Publisher
SPRINGER-VERLAG
Issue Date
2001-03
Language
ENG
Keywords

LITHOGRAPHY

Citation

MICROSYSTEM TECHNOLOGIES, v.7, no.1, pp.1 - 5

ISSN
0946-7076
DOI
10.1007/s005420000062
URI
http://hdl.handle.net/10203/2755
Appears in Collection
ME-Journal Papers(저널논문)
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