Surface Electronic States and Electrostatic Attractive Forces between Metals or Semiconductor and Tribocharged Polymers
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J21.1.1
Surface Electronic States and Electrostatic Attractive Forces between Metals or Semiconductor and Tribocharged Polymers Yoshihiro Momose, Masahiro Umeki, Daisuke Suzuki, and Keiji Nakayama1 Department of Materials Science, Ibaraki University, Hitachi 316-8511, Japan 1 National Institute of Advanced Industrial and Science and Technology, Tsukuba 305-8564, Japan ABSTRACT A new simple method for measuring a long-range electrostatic attractive force between metal and semiconductor substrate and charged polymer surfaces has been developed to make clear the effect of the electronic nature of substrate surfaces. Nickel, titanium, and silicon wafer substrates were subjected to various surface pretreatments. The surfaces of polystyrene and polytetrafluoroethylene sheets were positively and negatively charged by triboelectrification, respectively. A progressive increase in the attractive force was observed with a decrease in the distance between the substrate and polymer surfaces. The magnitude of the attractive force was greatly influenced by the substrate pretreatments and the polymers with the oppositely charged surface. The electronic nature of the substrate surfaces evaluated by temperature programmed photoelectron emission method was well correlated with the attractive force. The electrostatic induction generated at the substrate surface is considered to govern the attractive force. INTRODUCTION The development of process monitors capable of examining surfaces and interphases in ambient production environments is one of the crucially needed areas of research [1]. Environmental interactions of real surfaces are of critical importance in many surface processes such as adhesion, coating, and tribology [2], while little is known about the monitoring from the electronic nature of real solid surfaces [3,4]. Static charge caused by triboelectric charging [5] produces critical problems in semiconductor manufacturing and other high-technology industries [6]. The purpose of the present study is to develop a new method for measuring the electrostatic attractive force between metal and silicon wafer substrate and triboelectrically charged polymer surfaces. We have developed the method for examining the electronic nature or behavior of real metal surfaces using photoelectron emission phenomena as a function of temperature [7-10]. The apparatus of this method called temperature programmed photoelectron emission (TPPE) is composed of a gas-flow Geiger counter with Q gas at atmospheric pressure. The TPPE method can be applied to real metal and semiconductor surfaces with an adsorbed layer. The relationship of the electronic nature of metal and semiconductor surfaces to the attractive force with the polymers was investigated in this study. EXPERIMENT Commercial rolled Ni and Ti sheets (purity 99.5%, thickness 0.1mm) and polished Si wafer [(100) plane, resistance > 1000Ωcm, thickness 525µm] were used. Polystyrene foam (PS) (thickness 5mm, size 30x70mm2) and polytetrafluoroethylene (PTFE) (thickness 2mm, size 30x70 mm2) were empl
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