Proton beam writing is a lithographic technique by means of direct writing of focused MeV proton beam, with potential to overcome the limit of the electron beam (EB) lithography. The unique features of the PBW include high-aspect-ratio structures with thickness up to several tens of μm. In this paper, we demonstrate the unique microstructures produced by proton beam writing. Replication of patterns written by PBW was also demonstrated for improved productivity. Introduction of commercially available resists other than typical resist such as PMMA and SU-8 was also discussed. Dielectrophoretic devices for electric filters of microbes such as E. coli were demonstrated as a successful application of high-aspect-ratio structures fabricated by PBW. Recent development of a compact proton beam writer is also introduced.

  A MeV gaseous ion nanobeam system with a compact size (compact MeV ion nanobeam system) has been developed for a proton beam writing (PBW) technique to be used in many experimental laboratories. Gaseous ion beam, which is generated by a plasma-type ion source, generally has a large source size of several hundreds micrometer in diameter at the extraction anode hole of the ion source. Therefore, high demagnification is a key point in a compact focusing lens system to obtain MeV proton nanobeams of 100 nm or less in diameter. In Japan Atomic Energy Agency (JAEA), the compact MeV focusing lens system, designed in combination of the double-acceleration lens system and a MV acceleration tube, leads us to form the 1.7 MeV proton beam of 100nm in diameter.

  High LET particles penetrating polymeric materials are releasing their kinetic energy within a limited nm-sized area along their trajectories, leading to insoluble nano-gels via cross-linking of the polymer backbones. The nano-gels are fairly isolated on the substrate by the subsequent development procedure with several solvents, and are visualized clearly as atomic force or scanning electron microscope images. The size dependence on LET values of the incident particles is well interpreted based on the radial dose distribution in ion tracks. The present technique demonstrates ultra-wide feasibility to produce 1D-nanostructures based on “any” kind of polymer materials.

  In this study, we develop the formation process of Ni electrodeposited micro patterns, which is used for MEMS devices or nano-imprinting. The purpose of my study is creating the new process of fabricating 3-D complicated micro-pattern or micro-devices using electroforming and proton beam writing. In general, “Through mask process” (like a LIGA process) is usually used to fabricate Ni electrodeposited micro patterns for making MEMS devices or microfabricated-molds. The strong point of “Through mask process” is the simple shape of the electrode. It makes the deposition process easy, because the electrodeposited films just glow up from the bottom to top surface of the mold. And the shape of the electrodeposited films is the same as the electrode pattern from the bottom to top, like a simple pillar shape. However, this process also has some problems. In case of using “Through mask process”, it is difficult to fabricate the complicated 3-D shaped structures, which are bended, parted or severed at some part of the structure between the bottom and top, like a device with a micro sensor or micro total analysis system. In order to overcome these limitations, we try to fabricate Ni electrodeposited micro patterns using “the Damascene process” and proton beam writing.

  Pairs of gold nanodisks 40 or 70 nm in diameter were fabricated in silica by electron-beam lithography. On irradiation by 110-MeV Br¹⁰⁺ ions, the nanodisks elongated to form nanorods; elongation occurred in the direction of propagation of the ions. The aspect ratios of the Au nanorods increased with increasing ion flux density or fluence and with decreasing diameter of the nanodisks. The elongation mechanism can be explained in terms of a thermal spike model. Optical absorption spectra of the nanorods pairs before and after ion beam irradiation at a normal incident angle were compared. Au nanorods pairs were also fabricated with ion beam in a incident angle of 45° and the optical absorption were measured.