Based on a moving mask deep X-ray lithography concept, a new deep X-ray exposure system with multi stage has been built up, which can fabricate 3 dimensional microstructures with controllable free shaped wall such as inclined, curved and vertical wall. The system has 6 stages, an X-stage and a Y-stage for substrate scanning, a substrate tilt stage and a substrate rotation stage for controlling an incident X-ray angle to a substrate, an X-Y stage for mask movement and X-Y stage for substrate and mask alignment. The system performance has been confirmed by fabricating microstructures such as gratings, micro grid and micro prism. IntroductionDeep X-ray lithography is a very attractive technique to realize high aspect ratio microstructures due to the features of X-ray such as short wavelength and high parallelism. Especially, LIGA process which based on the deep X-ray lithography technology combined with subsequent electroplating and molding technique can replicate precision microstructures made of various material such as plastic, metal and ceramics is thought as one of the promising micro-machining technology. However, normal deep X-ray lithography and LIGA process can only fabricate the microstructures with vertical wall, which have been greatly limited their application field.To overcome this limitation, some approaches have been proposed. Feinerman et al.[1] proposed a system that can move a substrate against an X-ray mask to form three dimensional (3-D) microstructures. Katoh [2] proposed a photo etching process of PTFE using a similar exposure system that can move a substrate against an X-ray mask. Although the 3-D microstructures can be realized on non-planar substrate surface by these previous approaches, a fabricated microstructures have walls parallel to the incident X-ray. In this viewpoint, the concept of these approaches are as same as that of the conventional deep X-ray lithography.We once proposed the moving mask deep X-ray lithography technology (M 2 DXL) to fabricate the structure with controllable inclined or curved wall [3]. This technology has been successfully demonstrated their feasibility for realization of complicated microstructures such as grating [4] and micro nozzle structures [5]. The principle of the moving mask exposure is schematically stated by an example shown in Fig. 1. When the X-ray mask with circular window is moved circularly at a constant speed, the trapezoid distribution of the absorbed X-ray energy is formed on the PMMA substrate. Since the processed depth of PMMA is approximately in proportion to the absorbed X-ray energy by PMMA, a truncated conical PMMA structure is obtained. The feature of this technology is that non-vertical wall can be realized by controlling the distribution of the absorbed X-ray energy on a PMMA substrate intentionally. By combining various mask patterns and mask movement trajectory [5], microstructures with free shaped wall can be realized.Although the moving mask technology is a powerful technology, it has limitation for the wall profile of negativ...

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Two methods, 'Forward Approach" and "Inverse Approach", to fabricate complicate 3dimensional microstrucm by deep X-ray lithography have been developed. In the "Forward Approach", expome energy distribution on a PMMA substrate was calculated using, X-ray mask pattern and mask moving trajectories. Two Wment micro-nozzle patterns were fabricated to demonstrate the feasibility of this approach. From the comparison between e c t i o n and experimenf a new phenomenon related to the long lifethe radicals WBS observed. As the "Inverse Approach", a method to detgmine the optimum mask moving trajectory using Fourier transformation was developed.

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A compact nanosecond pulsed X-ray source is described. The X-ray source consists of two important subassemblies: a high-voltage pulse generator and an X-ray diode. The high-voltage pulse generator is designed based on the principle of triple resonance circuit producing a high-voltage pulse across the X-ray diode with amplitude of up to 500 kV. The X-ray diode is a sealed transmission target X-ray tube. Its cathode is comb structure formed from thin tungsten sheets with thickness 50 µm, while its target is made of 100 µm titanium film. The X-ray dose at a distance of 20 cm from the diode is 20 mR per pulse, while the diode voltage is 512 kV. In the case, the full-width at half-maximum of the X-ray pulse is ~5 ns.