During spray coating a substrate – for instance a structured silicon wafer – is coated with a photosensitive resist via spraying.
In order to do so the substrate is placed on a chuck and is held via vacuum suction. The resist is sprayed onto the wafer through a nozzle. An optimized way of moving the nozzle across the wafer allows for a homogenous coating of the substrate. The liquid resists used for spray coating usually have a very low viscosity in order to achieve a very fine formation of drops.
Compared to spin coating, spray coating is the ideal process solution to homogenously coat substrates with high topographies.