We developed a new light-scattering instrument for sizing single particles, which measures the light scattered by a single particle with a photodiode array and determines the particle diameter from Mie theory. A linearly polarized laser beam is irradiated onto a single particle and photodiode sensors detect the angular scattering pattern. The detection angle ranges from 49.3 to 126.4 degrees, and both perpendicular and parallel components of the polarized light are measured. For the calibration of the instrument, we used PSL (polystyrene latex) particles whose nominal diameters were 1.001, 1.274, and 1.696 μm. Average sizes of PSL particles measured by the instrument were, respectively, 0.960, 1.171, and 1.650 μm.
Behavior of air bubbles injected into a water vessel of 30°sector model in half length scale of a nuclear reactor vessel is observed in a water pool and classified into characteristic zones according to bubble formation types. Released gas forms globule bubbles in the release zone above an air injection nozzle. In the split/coalescence zone, globule bubbles split into small bubbles of about 10 mm diameter and these small bubbles rise in the water pool to coalesce into large bubbles near the pool surface. Depletion of 0.3 - 2.7 μm dioctyl sebacate (DOS) aerosols injected into the water pool is determined under a stagnant flow condition of the water pool. Deposition of DOS aerosols in tubing from an aerosol generator to the water vessel and the water droplets generated by the breakage of bubbles at the pool surface are measured in error estimation. The decontamination factor (DF) of DOS aerosols rising through the water pool increases in an exponential function of the water head between 0 and 3 m, giving a value of over 100 at 3 m water head. Aerosol diameter has a weak influence on the value of DF.
Feasibility of a plastic wafer box with a UV/photoelectron cleaning unit (UV unit) for a practical application has been investigated. Chemical contaminant evaluations for the box air and Si wafer surface were carried out with GC/MS. Metal-oxide-semiconductor (MOS) capacitors were fabricated after the storage in various boxes before or after gate oxidation and their reliability tests were carried out. The total ion chromatogram (TIC) spectra showed a dramatical reduction of organic contaminants adsorbed on Si wafers stored in the newly developed poly-ether sulfone (PES) box equipped with the UV unit. We found that the injected charge at which the gate oxide undergoes the final hard breakdown is markedly improved by the installation of the UV unit to the PES box. However, the soft breakdown of gate oxides was so sensitive to the organic contaminants on Si surfaces that it hardly depended on the typesed of used storage boxes. We concluded that the PES/UV unit wafer box is useful for the practical wafer box.