Abstract: Microprocessor controlled isopropyl alcohol vapor dryer system for robotic drying of wafer cassettes containing wafers or substrates. A wetted wafer or substrate is robotically placed into a virgin isopropyl alcohol vapor zone. The wetted surface and free-moving contaminants are replaced by a layer of isopropyl alcohol (IPA) which condenses on the surface. The dryer then robotically moves the IPA coated wafer or substrate into an upper cooling zone causing the isopropyl alcohol layer to flash off of the substrate surface, leaving the surface completely dry to a molecular level. IPA vapors are heated at the bottom of a quartz tank and maintained as a vapor by electric heating panels surrounding the quartz tank.