A METHOD FOR PRODUCING NONSPHERICAL MONODISPERSE PARTICLES USING INTEGRATED-CIRCUIT FABRICATION TECHNIQUES

Integrated circuit (IC) microchip fabrication techniques were used to produce silicon dioxide particles of respirable size and precisely defined shape. Standard IC film deposition and lithographic processes were employed, yielding SiO2 particles of uniform thickness (1 μm) in a variety of sizes and shapes. Test particles of special interest included discs of diameter 2, 4, 8 or 12 μm; and fibers of width 1 μm and length 5, 10, 20 or 40 μm. Approximately 107 particles could be produced on a standard 100 mm diameter silicon wafer. The particles were 'floated' off into suspension by dissolving a sublayer of aluminum and were aerosolized by nebulization. Airborne particle concentrations of the order of 103 l-1 were obtained. Examination of the particles in a scanning electron microscope, both before and after aerosolization, showed that they were uniform in shape with sharply defined edges. © 1990.