Hironori Atarashi

Interfacial Width in Polymer Bilayer Films Prepared by Double-Spin-Coating and Flotation Methods

A spin-coating method with the aid of selective solvents has been used to construct multilayer structures for organic devices under the assumption that the solvents do not invade a preformed structure. To confirm the assumption, we examined the interfacial width (lambda(i)) of model polymer bilayers, composed of polystyrene and perdeuterated poly(methyl methacrylate), prepared by spin-coating and flotation methods. Neutron reflectivity measurements revealed that the lambda(i) value was larger for the spin-coating method than for the flotation method. These results cast doubt on the validity of the assumption. This knowledge should be kept in mind when this method is applied to construct multilayer structures.

Structural analysis for a poly(methyl methacrylate) ultrathin film in water by neutron reflectivity

Density profiles of a perdeuterated poly(methyl methacrylate) (dPMMA) film spin-coated on a substrate in water (H2O) and deuterated water (D2O) were examined along the direction normal to the interface by specular neutron reflectivity (NR). Although H2O and D2O were typical non-solvents for dPMMA, their interfaces were more diffuse than the air/dPMMA interface due to the swelling caused by the sorption of H2O and D2O molecules. An isotopic effect on aggregation structure of the dPMMA film in water was also discussed.

High-space resolution imaging plate analysis of extreme ultraviolet (EUV) light from tin laser-produced plasmas

With the advent of high volume manufacturing capabilities by extreme ultraviolet lithography, constant improvements in light source design and cost-efficiency are required. Currently, light intensity and conversion efficiency (CE) measurments are obtained by charged couple devices, faraday cups etc, but also phoshpor imaging plates (IPs) (BaFBr:Eu). IPs are sensitive to light and high-energy species, which is ideal for studying extreme ultraviolet (EUV) light from laser produced plasmas (LPPs). In this work, we used IPs to observe a large angular distribution (10°-90°). We ablated a tin target by high-energy lasers (1064 nm Nd:YAG, 1010 and 1011 W/cm2) to generate the EUV light. The europium ions in the IP were trapped in a higher energy state from exposure to EUV light and high-energy species. The light intensity was angular dependent; therefore excitation of the IP depends on the angle, and so highly informative about the LPP. We obtained high-space resolution (345 μm, 0.2°) angular distribution and grazing spectrometer (5-20 nm grate) data simultaneously at different target to IP distances (103 mm and 200 mm). Two laser systems and IP types (BAS-TR and BAS-SR) were also compared. The cosine fitting values from the IP data were used to calculate the CE to be 1.6% (SD ± 0.2) at 13.5 nm 2% bandwidth. Finally, a practical assessment of IPs and a damage issue are disclosed.