Preliminary study on development of 300 kV compact focused gaseous ion beam system

Okubo, Takeru; Ishii, Yasuyuki; Miyake, Yoshinobu*; Kamiya, Tomihiro

Focused proton beam of several hundreds of keV with micrometer scale range become a powerful tool for high aspect ratio 3-Dimensional structures in proton lithography. A new 300 kV compact focused gaseous ion beam (gas-FIB) system with three-stage acceleration lens was constructed at JAEA. The preliminary experiments of formation of the focused gaseous ion beams were carried out to show the availability of the gas-FIB system as a writing tool for 3D proton lithography. As a result of the experiments, it was proved that the focal point was kept at the same position under changing the kinetic energy but with keeping the kinetic energy ratio constant, which was defined as the ratio of kinetic energy in object side to that in image side for the third acceleration lens. This characteristic of the gas-FIB is a good point to suggest the 3D proton lithography changing penetration depth in a sample by varying the beam energy.