Nanometer X-ray lithography

New developments for X-ray nanomachining include pattern transfer onto non-planar surfaces coated with electrodeposited resists using synchrotron radiation X-rays through extremely high-resolution masks made by chemically assisted focused ion beam lithography. Standard Ultraviolet (UV) photolithographic processes cannot maintain sub-micron definitions over large variation in feature topography. The ability of X-ray printing to pattern thin or thick layers of photoresist with high resolution on non-planar surfaces of large and complex topographies with limited diffraction and scattering effects and no substrate reflection is known and can be exploited for patterning microsystems with non-planar 3-D geometries as well as multisided and multilayered substrates. Thin conformal coatings of electro-deposited positive and negative tone photoresists have been shown to be X-ray sensitive and accommodate sub-micron pattern transfer over surfaces of extreme topographical variations (over 100 microns). Chemically assisted focused ion beam selective anisotropic erosion was used to fabricate Xray masks directly. Masks with feature sizes less than 20 nm through 7 microns of gold (aspect ratio similar to 350) were made on bulk silicon substrates and X-ray mask membranes. The technique is also applicable to other high density materials. Such masks enable the primary and secondary patterning and/or 3D machining of Nano-Electro-Mechanical Systems (NEMS)s over large depths or complex relief and the patterning of large surface areas with sub-optically dimensioned features.