Plain-pattern to cross-section transfer (PCT) technique for deep x-ray lithography and applications

This paper presents a novel fabrication method for three-dimensional microstructures using deep x-ray lithography. The microstructures were fabricated including sloped sidewalls and curved surfaces by exposing a synchrotron radiation beam to a moving x-ray resist. The technique, the so-called plain-pattern to cross-section transfer (PCT) technique, has been developed as an extension to conventional 2.5-dimension lithography. The fabrication of PMMA microstructures has been demonstrated with surfaces as smooth as 10 nm of RMS roughness. Various applications, e.g., micro-optic, bio-medical and some components of MEMS devices have been realized. Two microstructures have been given as examples: microlens arrays and microneedle arrays. The resulting arrays can be employed to fabricate moulds by electro-deposition for further batch-processing using the LIGA process.