Lithographic Characters of High Molecular Weight Carbonyl Containing Polystyrene for Electron Beam Irradiation

• Published in: KOBUNSHI RONBUNSHU Vol. 35; no. 1; pp. 7 - 13
• Main Authors: KAWAI, Wasaburo, SEKIKAWA, Kyozo
• Format: Journal Article
• Language: Japanese
• Published: The Society of Polymer Science, Japan 01.01.1978
• Subjects: Contrast; Electron Beam Irradiation; Emulsion Copolymerization; Lithographic Character; Sensitivity; Styrene-Carbon Monooxide Copolymer
• ISSN: 0386-2186; 1881-5685
• DOI: 10.1295/koron.35.7

Carbonyl containing polystyrene (styrene-carbon monooxide copolymer) prepared by emulsion copolymerization of carbon monooxide with styrene were examined their characters for electron beam lithography. The sensitivity which was represented by dose to halven the thickness of a normalized film increased with increasing the molecular weight of the copolymer, while it was independent of carbon monooxide unit content. For fractionated polymer a given content of carbon monooxide unit, similar tendency was also recognized. Further, a high molecular weight portion of polystyrene prepared with emulsion polymerization showed an enhancement in sensitivity for electron irradiation. Moreover, carbonyl containing polystyrene was found to have a contrast value of more than 1.0 which is required for practical use. The contrast is dependent not only on molecular weight but also on carbon monooxide unit content in the copolymer: the copolymer with the higher molecular weight and the more carbon monooxide unit content has the higher contrast value. Then, a fine developping pattern was prepared on a copolymer sample as a negative electron beam resist. It was recognized with electron microscope that the minimum line width in the pattern was 0.5 micron. The effect of molecular weight distribution upon contrast value was also described.