Abstract
This dissertation presents a novel x-ray machining system for the fabrication of three-dimensional microstructures with free-form surfaces. The structures with different sizes and various shapes can be created by a single mask combining with a moving x-ray resist along several precise paths. By adjusting the coefficients of motion such as path types, overlaps and velocities, various microstructures with specific complex features have been successfully fabricated with simple geometric patterns of the mask. The x-ray free-form micromachining system consists of a high performance piezoelectrical nano-stage with 1.5 nm resolution and a stroke up to 200 μm. The error of motion is controlled below 1.3 %. Pertinent systematic studies on the lithography apparatus, the fundamental properties of PMMA and the simulation for 3D structuring are undertaken to further clarify the validity of the system. Various 3D PMMA microstructures have been successfully fabricated as a demonstration of the proposed method. The finishing structures have specific characteristics such as axial symmetries and free-form surfaces with the maximum depths varying from 2.7 to 19.6 μm. The average error rate between simulations and experiments is 7.4 % approximately. The average surface roughness is controlled below 40 nm. The result suggests that the circular pattern is superior to the square one for the fabrication in view of good surface roughness The new technique of fabricating 3D gradually thinning holes on a suspended film has successfully manufactured a suspended film with the thickness of 2.5 μm. The 3D hybrid structures with dimensions of 0~1.0, 1.2, 1.7 μm are also built.