Positive-tone diazonaphthoquinone/novolak resist on a 42-alloy (Fe:Ni=42:58wt%) substrate was irradiated by the second harmonic of Nd:YAG (Y3Al5O12) laser (532nm). The resist was removed (stripped) completely, despite the presence of hexamethyldisilane (HMDS) and the pre-bake condition of the resist. There was no apparent damage to the substrate by the laser. In contrast, this resist on a Si wafer could not be removed completely, and the substrate was occasionally damaged as well. The fourth harmonic of Nd:YAG laser (266nm) was used to irradiate the resist on the Si wafer, ablation was effective. There was no apparent damage to the substrate. This resist does not absorb the energy of the laser at 532nm because it is optically transparent (over 90%) above 500nm. However, its transmittance was very low (under 5%) below 300nm. The resist therefore absorbed the energy of the 266nm laser, and was removed (ablated). This development addresses environmental concerns because expensive and toxic chemicals are not used.

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Diphenyliodonium 4-(3-N,N-diethylamino-6-diethyliminium-9-xantenyl)-3-sulfonato-phenylsulfonate was designed and prepared. The diphenyliodonium salt with a food dye as a counter anion showed good thermal stability, and had a decomposition temperature of 201.1°C. From the results of our investigation, the mechanism of acid generation is considered to be intramolecular electron transfer from the excited dye moiety to the iodonium. The photosensitivities of the photopolymer with a tetrahydropyranyl protecting group were 2.09 and 0.84 J/cm² at 488 nm and 514 nm, respectively.

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We have reported the luminescent and photochemical behaviors of poly(4-vinylpyridine) (P4VPy) and derivatives in solid. To analyse the complicated emission bands of these poly(vinylpyridines) (PVPys), we induced the Emission Contour Maps (ECMs) in our previous report. With ECMs, the emission bands originated from free-PVPys, hydrogen-bonded PVPys, protonated PVPys, and quaternized PVPys appeared to have some characteristics. Though PVPys are said that they show similar absorption spectra in free or protonated states, their emission bands and emission yields are significantly influenced with protonation. In our previous study, the change in proton / hydrogen (H+/H) concentration seemed to increase difficulties on the analysis of these emission bands. To avoid the change in H⁺/H concentration, we used a polymeric H⁺/H donor, poly(acrylic acid)(PAA). The ECMs of resultant polymer complexes between PVPys and PAA were determined. Some features of the emission bands in their ECMs were discussed.

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The rheological properties of UV flexographic (flexo) inks were investigated. UV flexo suspensions of carbon black in liquid medium containing various binding materials, such as acylate pre-polymers, di-/multi-functional monomers, and diluents, were used as sample inks. The inks were characterized on a rheometer in terms of steady and dynamic behaviors. The rheological properties of polymer-pigment systems are a function of some interfacial parameters that characterize the degree of "affinity" of pigment surfaces to the polymer medium. The addition of pigments into liquid medium introduces polymer-pigment junctions besides the polymer-polymer junctions due to entanglement. These newly created junctions arise from the sorption of pigments to the polymer chains. In this study, we found that the frequency dependence of storage modulus G' at a certain strain amplitude is proportional to the number of acryloyl groups in the multi-functional monomer (TMPTA<PETTA<<DPHA). The chemical difference due to chain length (TMPTA<GPTA) is another factor affecting the rheological properties of UV flexo ink. In addition, we surmise that a transient network structure is formed by mechanical interactions that are induced by the addition of high concentrations of small solid particles such as carbon black to a polymer or a multi-phase solution. In such a system, the particle chains form the network structure, although the formation of polymer bridges by adsorbing to adjacent particles is another possibility.

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Transient absorption spectra of electron beam sensitive polyimides and their model compounds were measured by the nano second pulse radiolysis using a LINAC. Transient absorption bands at 550 nm and 760 nm were observed for the benzophenone-containing-polyimide, PI(BTDA/DEDPM) in THF solution, which are assigned to triplet state and radical anion, respectively. The radical anion was also observed even in CH2Cl2 solution as well as the absorption of radical cation, showing that strong electron affinity of imide moieties. The active intermediate of the pattern formation of PI(BTDA/DEDPM) was determined to be the triplet excited state.

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A novel image formation system was created using a photo-initiated ring-opening cationic polymerization of epoxides. This photopolymer incorporates cationic amplification based on acid catalysis as a route to high sensitivity, using a unique photo-acid generator (PAG) to induce the formation of a soft acid. The films formed from these photopolymers consist of various polymers, epoxide monomers, and 4-cumenyl-4'-tolyliodonium tetrakis(pentafluorophenyl)borate (CTI-TB). The reactions and rates of the polymerizations in the polymer film were characterized using FT-IR spectra and RT-IR spectra. A preliminary lithographic evolution of this material revealed that negative images with features in the 0.75 μm range could be resolved.

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With the invention of the atomic force microscope (AFM), we have been equipped with the appropriate tools to clarify surface and interface properties of condensed matter on nanometer scale. As an application of AFM on resist processing, the present author has already studied resist pattern adhesion, Young's modulus estimation, Surface hardened layer analysis by tip indentation and manipulation of polymer aggregate. Moreover, nanobubble analysis for immersion lithography has been analyzed. The AFM technique gives useful information to the field of the designing of resist processing.

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Polymer bound PAG resists, poly(4-hydroxystyrene-co-2-ethyl-2-adamantyl methacrylate-co-PAG1) [poly(HOST-co-EAMA-co-PAG1)] and poly(4-hydroxystyrene-co-2-ethyl-2-adamantyl methacrylate-co-PAG2) [poly(HOST-co-EAMA-co-PAG2)] have been synthesized and evaluated as potential components of EUV resist materials with enhanced lithographic properties such as photospeed and Line Edge Roughness (LER). The polymer bound PAG resist exhibited faster photospeed and lower LER than the corresponding blend of photoacid generator (PAG) and copolymer resists, poly(HOST-co-EAMA) with blend PAG3 (Triflate) and poly(HOST-co-EAMA) blend with PAG4 (Nonaflate). These results imply that this novel resist system has potential advantages over conventional resists and should be further explored for application in EUV lithography. Furthermore, use of different counter anions such as triflate and nonaflate influenced the lithographic performance. Sub-100 nm features were obtained with improved lithographic performance such as photospeed and LER using EUV exposure.

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