This paper concerns with the basic investigations on the wet chemical etching of semiconductors. First, a method to observe the etched cross-section of aluminum layer is developed. It is applied to the observation for the cross-section of a test piece etched in a quiescent etchant. The observation successfully makes clear the time variation for the geometry of the etched cross-section, and elucidates the effects of the resist width on the geometry. Secondly, the numerical simulation for the etching process is performed. The simulated geometry of the etched cross-section is confirmed to agree with the observed result, indicating that the present numerical simulation is effectively used to predict the geometry of the etched cross-section.

The behavior of arc in molded case circuit breaker is studied by computational fluid dynamics simulation (CFD) with moving electrode taking account of the metal vapor (Cu, Ag/W, Fe) and the decomposed gases (C02, H2). The background fluid is air and the electric current is 820A DC. The circuit breaker consists of copper electrodes, arc runner, magnet, splitter plates and molded case. The mesh-morphing and re-meshing technique is used to represent the motion of electrode. With local thermal equilibrium (LTE) assumption, thermodynamic property of arc plasma is calculated by temperature, pressure, and gas composition. The simulation is performed by commercial software STAR-CCM+.It is shown that the motion of arc from electrode to arc runner is reproduced successfully, and the cooling effect of metal vapor has significant influence on the temperature of arc plasma.

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