High-aspect-ratio micromachining via deep X-ray lithography

High-aspect-ratio microsystems technology (HARMST) can be implemented by using thick photoresist technology, which requires X-ray photons for exposure. This was first realized in Germany via the so-called LIGA process. To make this process cost effective, exposures with high-energy photons were introduced in 1993 via a University of Wisconsin-Brookhaven National Laboratory cooperation. The addition of a solvent bonded resist technology and replanarization after electroplating and X-ray mask aligning yield a HARMST processing sequence that uses large-area, sequential X-ray masks without diaphragms. This technology may be applied to precision engineered parts which do not involve electronics. The processing sequence is also used for high performance linear and rotational, magnetic and electrostatic actuators. System applications in optics involve spectrometers and other devices. A discussion of US and world wide efforts in HARMST points at increasing demands for this type of processing tool.