Abstract
X-ray lithography was good at fabricating high resolution and high aspect ratio microstructures. But this process could only fabricate microstructures with vertical wall which has largely limited the versatility in the applications of LIGA process. In order to apply the process to various applications. The moving mask technique has been developed to realize 3D microstructures with free shaped wall. In this study, we try to fabricate 3D microstructures using the moving mask technique. First, we simulated the exposed dosage distribution over a photoresist by using DoseSim software, coupled with the experimental results of exposure and develop. We found the minimum dosage which would be etched by GG developer, then drew the relationship between exposed dosage and processed depth. By combining UV lithography with subsequent electroforming and etching technique, we have produced an X-ray mask with good absorptivity of X-ray dosage. In the moving mask technique, the shape of a microstructure is defined by controlling a mask pattern and motion path of a photoresist. We have successfully produced 3D microstructures with special shape. In addition, we found a new phenomenon of swelling effect of PMMA. First, we looked for the possible reason to cause swelling effect. The experimental results showed that PMMA will not be dissolved by GG developer when dosage is less than 200J/cm3. On the contrary, microstructures were produced by swelling effect of PMMA. The main influences of swelling effect are exposed dosage and develop time. We have produced microstructures with various height by controlling both influences.