A novel way developed to estimate and design a reflector for reflective color LCDs which is based on the discovery that the shape of surface bumps on the reflector is actually a concurrence of multiple micro flat mirrors. Scattering of the reflector was calculated from the slope angle distribution of these micro-flat mirrors. This enabled us to determine the ideal bump shape for reflective color LCDs. Accuracy was confirmed by analyzing actual reflectors, and a nearly ideal reflector was fabricated by optimizing bump shape.
Copper is a promising candidate to replace aluminum in ULSI metallization and providing better conductivity and reliability. ULSI metallization is conducted by electrodepositing copper from ethylenediamine complex baths using the additives glycine, ammonium sulfate, and a small quantity of 2, 2′-bipyridyl. This bath exhibited good throwing power, and filled trenches and contact holes on silicon wafers by copper deposits with good mechanical properties. As mentioned, application to ULSI metallization formed by electrodeposition of copper using ethylenediamine complex baths appears possible.
The effect of laser surface treatment on the resistance of high-temperature oxidation of TiAl intermetallic compound was studied using 500W CO2 gas laser equipment. The diameter of the laser spot was about 100μm and scanning was 95mm·s-1. Laser surface treatment formed a layer solidified by rapid quenching on the TiAl surface. The oxidation of TiAl at 1273 K in a pure O2 atmosphere, which followed the parabolic rate law, was reduced to less than half by laser surface treatment. Scale formed on the laser surface-treated TiAl after the oxidation experiment was thinner than that formed on nontreated TiAl and contained a continuous, dense Al2O3 layer. No such continuous Al2O3 layer was observed for scale formed on nontreated TiAl, indicating that, for laser surface-treated TiAl, the continuous Al2O3 layer in the scale acted as a diffusion species barrier, inhibiting scale growth.
Stainless steel sheets were electrolytically etched to fabricate fine patterns on them. They were masked with a negative photoresist stencil and etched in an NaNO3 solution as a function of applied voltage (4-12V), electrode gap (5-40mm), and pattern width (25-1000μm). The etch factor exceeded 1.5 was obtained, showing that electrolytic photoetching was anisotropic. For wider grooves exceeding 200μm, the etch factor increased with increasing applied voltage. The electrode gap had no effect on the etch factor. To form perforations on sheets, a convex edge profile was developed when sheet breakthrough occurred. After certain overetching, however, a straight-edge profile was developed, because current concentrated on convex edges. For etching 50μm-thick stainless steel sheets at an applied voltage of 8V, overetching of about 80s was required to obtain a straight-edge profile. During overetching, etched groove width increased linearly with etching time at a rate of about 1μm/s for 8V etching, independent of pattern width. We applied this technique to realize masks for vacuum evaporation in fabricating electrode patterns for a quartz crystal microbalance and a microthermocouple pattern.
The electrode potential of high-purity aluminum foils for electrolytic capacitors moves from a high potential period to a stability period during early DC etching in hot hydrochloric acid. We observed changes in pit structures in transmission electron micrographs of films stripped from etched foils, and measured a potential change using a digital oscilloscope. Pitting attacks occurred around MgAl2O4 spinel or γ-Al2O3. Pits varied from hemispherical to half-cubic, and the etch tunnel growth was promoted by crystallographic dissolutions of the (100) faces. Pit wall surfaces of a half-cubic pit and part of the tips of etch tunnels were passivated. Both MgAl2O4 spinel and γ-Al2O3 crystals were observed at the metal ridges on the aluminum substrate by transmission electron micrographs of ultramicrotomed sections. Pits are considered to be initiated at cracks associated with oxide film crystallizations. MgAl2O4 spinel crystals were observed in a foil containing 123 wt-ppm magnesium after annealing at 445°C for 5h in an Ar gas atmosphere. At 575°C, γ-Al2O3 crystals were only observed in a foil containing 1 wt-ppm magnesium. The growth of MgAl2O4 crystals was accelerated above 1 wt-ppm magnesium.