AVS 50th International Symposium
    Nanometer Structures Tuesday Sessions
       Session NS-TuP

Paper NS-TuP26
Fabrication of Cylindrical Cu Nanorods on an Indium-Tin-Oxide Substrate

Tuesday, November 4, 2003, 5:30 pm, Room Hall A-C

Session: Poster Session
Presenter: S. Asakura, Waseda University, Japan
Authors: S. Asakura, Waseda University, Japan
K. Oda, Waseda University, Japan
A. Hozumi, National Institute of Advanced Industrial Science and Technology, Japan
A. Fuwa, Waseda University, Japan
Correspondent: Click to Email
Increasing attention has recently been paid to the fabrication of copper (Cu) arrays of nm-scale in order to realize an ultrahigh-density electron emission source. Among the several methods, the use of diblock copolymer (BC) thin film is promising, since an ordered nanoporous structure can be easily obtained from the copolymer thin film by chemical treatment. Here we report the fabrication of cylindrical Cu nanostructures onto an indium-tin-oxide (ITO) substrate through an electrodeposition using a BC thin film as a template. First, a mixture of polystyrene (PS, 70 wt.%)/polybutadiene (PB, 30 wt.%) BCs and dehydrated toluene was stirred for 2 h at room temperature. Next, the solution was spin-coated on the ITO surface and dried in air for 24 h at a temperature of 140 °C. Due to this treatment, the PB component formed cylindrical domains in a matrix of the PS component as confirmed by an optical microscope. Subsequently, the sample was photoirradiated with vacuum ultraviolet (VUV) light of 172 nm in wavelength for 30 min at 10@super 3@ Pa. As a control experiment, identical BC thin film/ITO sample was sonicated in dehydrated toluene for 30 min. Finally, each sample was treated in an electroplating solution to deposit Cu on it. Using a scanning electron microscope, we confirmed that the Cu deposition selectively occurred inside the cylindrical nanopores where the PB domains were photochemically eliminated. The cylindrically shaped Cu nanorods on the ITO surface were less than 800 nm in diameter and several hundreds nm in length. Our result presented here demonstrated that the PB domains were removed completely due to VUV irradiation and the PS matrix served as a mask to prevent Cu deposition. On the other hand, in the case of the chemical treatment, no Cu deposition was observed. This indicates that the PB domains still remained on the ITO surface. Our VUV treatment was found to be effective for preparing the nanoporous structures in the BC thin film.