In the development of photoresists for each wavelength, such as g/i-line, KrF and ArF, it was necessary to select suitable polymer platform in order to obtain enough transmittance of the wavelength being used. This paper reported syntheses of novel phenolic cyclic oligomers (naphthalene type calixarenes) and those physical properties. Very interesting behavior was observed caused to have cyclic structure. Pattern size reduetion of semiconductor products has been attributable to the development of lithographic technology.

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Bisphenol A based benzoxazine and bisphenol E or phenol novolac based cyanate ester resin were used. The melt viscosity of benzoxazine/cyanate ester resin compound was very low before curing reaction, and the high fluidity was preferable for manipulation. The cured resin (network polymer) based on benzoxazine/cyanate ester resin system had good heat resistance, electrical insulation and water resistance. New high performance phenolic network polymer has been prepared by blending cyanate ester resin and benzoxazine.

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Cresol formaldehyde novolac resins (Cre/Form) having hard properties cannot be applied minutely the positivetype photoresist material onto dry films. Therefore, a new development was needed, so we carried out the synthesis and application of cresol novolac resins having flexibility. The polycondensation reactions of cresols with succinaldehyde, glutaraldehyde, and adipaldehyde were carried to obtain cresol novolac resins. The obtained resins having both dissolving rate for alkaline aq. solution below 1000Å/sec and M_w over 3000 were chosen for the test. The 5 μm thick cast films of the obtained resin were applied onto polyimide films in order to evaluate the flexibility properties of the obtained resins by observation of their bent parts. Though the Cre/Form resin of the bent part was scattered, the obtained resins just cracked. The flexibility of the obtained resin was also confirmed from the results of the dynamic storage modulus measurement, too. The lithography performance of the obtained resin coated 1.5 μm in thickness onto the silicon wafer was examined. The residual membrane thickness was high (90%) and the resolution of the resist was up to 2.5 μm.

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The inhomogeneity of molded and cured phenolic resins was investigated from the viewpoint of the higher-order structure distribution using small-angle X-ray scattering (SAXS). The SAXS intensity distribution in the 4-mm-thick molded specimen indicates the presence of higher-order structure distribution that was caused by the inhomogeneity of the degree of the curing reaction in the molding process. The change in the SAXS intensity during baking process suggests that an insufficient degree of curing reaction at the molding process causes further formation and propagation of voids with sizes ranging from tens to hundreds of nanometers. The macroscopic change in strain during baking process was also investigated

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High-molecular weight phenol novolak resins (RN) and o-cresol novolak resins (oCR) were prepared in organic solvent. The molecular structure was determined by ¹³C-NMR measurements and computer simulation technique with a percolation model. It was found that RN was a branched polymer and a microgel formation was observed, arising from intramolecular reaction (cyclization). The solution properties of acetylated RN (Ac-RN) and acetylated oCR (Ac-oCR) were determined in good solvent and θ-solvent. Ac-RN behaved as a branched polymer. On the other hand, Ac-oCR showed linear polymeric properties, but Ac-oCR chain was more shrinkable and compact in θ-solvent than polystyrene, which is a typical linear polymer. The properties of high-molecular weight phenolic resins suppose to depend on the main chain structure composed from phenolic ring and methylene linkages. Phenolic cyclic oligomers can be readily formed due to this structural feature. New properties on the basis of the phenolic resin skeleton will be born by controlling reactivity of phenols.

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Polybenzoxazine is a novel type of phenolic resin obtained by the ring-opening polymerization of benzoxazine, which is easily prepared from phenols, primary amines, and formaldehyde. The versatile molecular design is a strong point of benzoxazine resin, and the properties of the cured resin can be manipulated easily and widely. Very often, the presence of phenolic hydroxyl group and intra- and inter-molecular hydrogen bonding is the key for the molecular design that lead to the cured resin having unique properties. The thermal properties can be easily improved by various approaches including the addition of crosslinkable units, the increase of rigidity, and the addition of fillers. The toughness is also improved by polymer alloying, by copolymerization with various monomers, and by the approach of high molecular weight benzoxazines. It is very interesting that the approach to enhance the toughness of polybenzoxazine very often improve the thermal properties. Preparation of functional polybenzoxazines is also ongoing by various approaches. Polybenzoxazine is currently being interested as a highly value-added novel resin. The achievement of shortening the curing time and lowering the curing temperature is expected to widen the application field to great extent.

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