Fabrication of 3D micro and nanostructures for MEMS and MOEMS: an approach based on combined lithographies.

X-ray lithography is an established technique for the micro fabrication of MEMS and MOEMS well known for low sidewall surface roughness, submicron critical dimension, and high aspect ratio. Recently the typical characteristics of this technique has been developed approaching new opportunities deriving by the possibility to perform tilted exposure and by the combined use with electron beam lithography that allow to shape with direct patterning already the final material in 3D micro and nanostructures. The general approach is to concentrate the complexity of the multi layer fabrication process required to obtain 3D nanostructures mostly on the lithographic process. This capability represent a micro-and nanofabrication tool enabling new technologies. In this paper will be shown a multiple-tilted X-ray lithography procedure combined with e-beam lithography to create sub-micrometric patterns of arbitrary shape buried in 3D structure. The use of deep x-ray lithography in multi exposure configuration has been also exploited for the production of biodegradable 3D scaffold structures and of micro needles based transdermal delivery tools fabrication.