Microfabrication: LIGA-X and applications

X-ray LIGA (Lithography, Electrogrowth, Moulding) is one of today's key tec hnologies in microfabrication and upcoming modern (meso)-(nano) fabrication , already used and anticipated for micromechanics (micromotors, microsensor s, spinnerets, etc.), micro-optics, micro-hydrodynamics (fluidic devices), microbiology, in medicine, in biology, and in chemistry for microchemical r eactors. It compares to micro-electromechanical systems (MEMS) technology, offering a larger, non-silicon choice of materials and better inherent prec ision. X-ray LIGA relies on synchrotron radiation to obtain necessary X-ray fluxes and uses X-ray proximity printing. Inherent advantages are its extr eme precision, depth of field and very low intrinsic surface roughness. How ever, the quality of fabricated structures often depends on secondary effec ts during exposure and effects like resist adhesion. UV-LIGA, relying on th ick UV resists is an alternative for projects requiring less precision. Mod ulating the spectral properties of synchrotron radiation, different regimes of X-ray lithography lead to (a) the mass-fabrication of classical nanostr uctures, (b) the fabrication of high aspect ratio nanostructures (HARNST), (c) the fabrication of high aspect ratio microstructures (HARMST), and (d) the fabrication of high aspect ratio centimeter structures (HARCST). Review ing very recent activities around X-ray LIGA, we show the versatility of th e method, obviously finding its region of application there, where it is be st and other competing microtechnologies are less advantageous. An example of surface-based X-ray and particle lenses (orthogonal reflection optics (O RO)) made by X-ray LIGA is given. (C) 2000 Elsevier Science B.V. All rights reserved.