The usefulness of thin (< 250 micrometers ) rigid graphite plates as x-ray mask substrates for micromachining and LIGA applications has been demonstrated. Rigid graphite offers unique properties, such as moderate x-ray absorption and optimal filtration of synchrotron radiation, relatively low cost, compatibility with additive (electroplating) and subtractive (etching, micromachining) processes for absorber patterning. The surface roughness of these substrates is associated with the inherent porosity of a commercially available rigid graphite material (typical R_a values are in the range of 1 - 2 micrometers ). The surface roughness of this rigid graphite sheet is reduced down to a 0.1 - 0.2 micrometers R_a value by polishing. To reduce surface roughness further and make the substrate usable for fine e-beam or optical absorber imaging, additional smoothing is required. In this paper, the surface characteristics of rigid graphite sheets are analyzed and a glazing technique developed to smooth the graphite surface is described. This technique employs hard baking process of novolac-based resins. An average R_a roughness value of approximately 5 nm was obtained after 5 coating using novolac-based AZ type resist.

Date Published: 3 September 1999
PDF: 5 pages
Proc. SPIE 3875, Materials and Device Characterization in Micromachining II, (3 September 1999); doi: 10.1117/12.360465

Published in SPIE Proceedings Vol. 3875:
Materials and Device Characterization in Micromachining II
Yuli Vladimirsky; Craig R. Friedrich, Editor(s)