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A corona discharge air ionizer is one of the most usefill equipment to control electrostatic charges on ULSI in the manufacturing processes. However, a conventional air ionizer generates various kinds of contamination. The dual jet air ionizer that has a jet emitter in a nozzle was proposed to reduce the contamination from an air ionizer. The ozone generation, the particle generation, and the cluster-7ike material growth to the emitter tip were investigated for the dual jet air ionizer as a function of the jet flow rates out of the emitter and the noale. These contamination generated from the dual jet air ionizer depended strongly on the flow rates and were lower than that from a conventional air ionizer. These contamination characteristics of the dual jet air ionizer were compared with adconventional air ionizer.

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Several simulationswere performed in order to estimate the effects of the nonuniformity of the SiC ceramic semiconductor microstructure on the electrical conductivity. The boundary potential model was used to ex press the electrical characteristics of the grain boundaries and the calculations were performed using the three-dimensional equivalent circuit in the simulations. These simulations show that the nonuniformity of the acceptor concentration or of the trap concentration at the grain boundary greatly affects the electrical conductivity of the SiC ceramic semiconductor. This is explained by the percolation theory. The influence of these nonuniformities should be carefully considered in order to design or to produce related devices.

We propose a self-controlling corona discharge air ionizer for the static neutralization of electronic products in manufacturing processes. This air ionizer automatically generates only the quantity of ions required to neutralize a charged product, without the need for a control system. This is possible as the device generates ions based on the combination of the electric field of the ionizer emitter, to which a threshold voltage is applied, and the electric field of the product. In this study, the required threshold voltage values were determined by assessing the relationship between the neutralization current and the emitter voltage. The neutralization speed and the final product voltage after neutralization obtained from the ionizer operating on AC voltage were investigated using a charged-plate monitor. The time span required to reduce the charge on a metal plate with a capacitance of 20 pF from 1000 to 100 V was found to be less than 1.0 s, indicating that this device has practical applications.