Abstract
Cresol (Cre) formaldehyde (Form) novolac resins (Cre/Form) having hard properties cannot be applied minutely the positive-type 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 stepwise reactions with m-cresols (m-Cre) and n-butyraldehyde (Bu) succeeding reaction with m-Cre and glutaraldehyde (Glu) were carried to obtain m-cresol butyraldehyde-glutaraldehyde novolac resins (m-Cre/Glu－Bu). m-Cre/Glu－Bu meeting the conditions of both a dissolving ratio for alkaline aq. below 300 Å/sec and Mw over 2000 were chosen for the obtained resins. 5μm thick cast films for applying onto the polyimides were prepared in order to evaluate the flexibility properties of the obtained resins by observation for their bent parts. Though the Cre/Form resin was scattered, the m-Cre/Glu－Bu resin was settled with just cracks. The flexibility of the m-Cre/Glu－Bu resin was confirmed from results of the dynamic storage modulus measurement, too. The lithography performance of the m-Cre/Glu－Bu resin coated at a 1.5μm thickness onto the silicon wafers was examined. The residual membrane thickness was high (97％) and the resist pattern was able to draw up to 4.0μm clearly.
