A semiconductor processor for spray coating wafers or other semiconductor articles. The processor has a compartment in which are mounted a wafer transfer, coating station and thermal treatment station. The coating station has a spray processing vessel in which a movable spray-head and rotatable wafer holder. The spray station has coating viscosity control features. An ultrasonic resonating spray-head is precisely supplied with coating from a metering pump. The heat treatment station heat cures the coating and then cools the wafer. The system allows coatings to be applied in relatively uniform conformational layers upon irregular surfaces.