Electrostatic Discharge Analysis under Ultra clean environment

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This project is a fundamental research of electrostatic charging and discharge problems, especially related with clean air conditions. Two electrostatic charge distribution measuring methods were proposed. One is surface charge distribution analysis in sub-micrometer scale, by using a piezoelectric scanning stage and an electrostatic force detector with optical interferometric distance measurement. The scanning unit operated good but the sensitivity of the force detector was not enough to detect localized charge because of the instability of a hand-made equipment. The principle itself is possible, but fine mechanical technology is requested. A space charge distribution measuring system by using nano second pressure pulse was newly developed where a piezoelectric polymer film of PVDF was first used as pressure generator. The sysem could detect the difference of plasma surface processing effect on stable polymer films. However, the real space charge in a thin dielectric film could not observed by that system because the final resolution of the sytem was only 7 micrometer. As anti-static process, surface treatment effects of a polymer film by low pressure plasma processing were tested by charge distribution analysis, thermally stimulated discharge current analysis (TSDC), contact angle of water droplet and others. They could detect such treatment effects and decay of them during a week. Environmental gas effect of plasma was not so large as estimated. Electrostatic discharge phenomena on a charged thin film was precisely analyzed by using electronstatic induction probe and magnetic probe (electromagnetic wave detection). Correlation between electrostatic charging and surface state was analyzed as a result of the project.