Kiyoshi Ichimura

Effect of end group structures of methacrylate polymers on ArF photoresist performances

The relationship between the sensitivity of ArF photoresist and the end group structures of copolymers consisting of (beta) -hydroxy-(gamma) -butyrolactone methacrylate (HGBMA) and 2-methyl-2-adamantyl methacrylate (MadMA) was investigated. The sensitivity is strongly dependent on the kind and amount of end groups. It has been found that the copolymer with relatively non-polar end group structure has higher sensitivity than that with polar end group structure, and that the sensitivity of copolymer with end groups of methylisobutyrate and 1-octhylthio moieties showed approximately three times higher than that of copolymer with end groups of isobutyronitrile and 2-hydroxyethylthio moieties. The difference of sensitivity among these copolymers has been discussed from the view point of the change of development rate attributed to the amount of carboxylic acid groups formed in the resist film by exposure of 193nm light.

Synthesis and properties of new chiral dopants containing a δ-lactone ring for practical ferroelectric liquid crystal mixtures

Abstract A series of new optically active δ-lactones were synthesized as chiral dopants for ferroelectric liquid crystals (FLCs). The response time of an FLC mixture containing 4 mol% (S)-2,2-dimethyl-5-[2-fluoro-4-(5-n-octylpyrimidin-2-yl)-phenoxy[methyl-δ-valerolactone was 25 μs at 25°C. (0–90 per cent change in light transmission, 10 V μm−1). The synthesis and properties of these materials as practical chiral dopants are reported.

Tacticity of methacrylic copolymers and their crosslinked polymers studied by pyrolysis–gas chromatography

Diad tacticity of methyl methacrylate (MMA) sequences in the copolymers of MMA and various acrylates and their crosslinked polymers was characterized by pyrolysis-gas chromatography (Py-GC) based on the relative peak intensities of the diastereomeric MMA tetramers in the pyrograms. The diad tacticity in the copolymers synthesized at a given temperature proved to be almost consistent with that of corresponding MMA homopolymers (PMMA) prepared under the same conditions. Furthermore, the diad tacticity of PMMAs was also consistent with that of the corresponding crosslinked polymers. These results suggest that the tacticity of MMA sequences in the polymer chains would be dominated by polymerization temperature, independent of the copolymerization and crosslinking.

Relationship between Molecular Structure and Induced Spontaneous Polarization for Chiral Dopants Containing an Optically Active Lactone

Abstract A series of new optically active γ-lactones were synthesized. The relationship between molecular structures and induced spontaneous polarization of optically active γ-lactones and δ-lactones has been investigated. The molecular shapes of chiral dopants, especially the alkyl chains extending from a lactone ring, were found to play important roles in the generation of spontaneous polarization.

New Chiral Dopants with an Optically Active Six-membered Ring for Ferroelectric Liquid Crystals. Effect of Direction of the Dipole Moment on Spontaneous Polarization

Abstract New chiral dopants containing an optically active six-membered ring with a cyano group were synthesized. New chiral dopants containing an optically active six-membered ring with an epoxy group were also synthesized and the effect of the direction of the dipoles on spontaneous polarization were discussed using them. The spontaneous polarization is thought to be influenced by the direction of the dipoles of the chiral moiety.

Effect of Zn Diffusion on the Properties of AlGaAs Double-Hetero Light-Emitting Diodes

The state of Zn diffusion on the heterointerface of 660 nm AlGaAs double-hetero (DH) light-emitting diodes (LEDs) was investigated by the electron-beam-induced current (EBIC) method. The p-n junction penetrates toward the n-cladding layer as a result of Zn diffusion when the carrier concentration of the p-active layer is greater than 1×1018 cm-3. The distance between the heterointerface and p-n junction was related to the optical output and modulation bandwidth of LEDs. For producing superior LEDs, it is important that the p-n junction coincides with the hetero interface or slightly penetrates into the n-cladding layer. The dependence of the Zn effective diffusion coefficient on the carrier concentration of the p-active layer and n-cladding layer was also investigated. Finally, it was determined that the suitable growth temperature of the active layer was around 850°C.