Resist can be aerosolized and sprayed through a nozzle that sweeps across a substrate. The advantage of spray coating is that, in contrast to spin coating, high aspect ratio features such as tall pillars or deep trenches, can be fully and uniformly coated. In contrast, coating high aspect ratio features is a shortcoming of spin-coating; centrifugal forces make the resist thicker on structures facing the rotation axis and thinner facing away. Spray coating also generates less waste compared to spin coating, an advantage if the resist is rare or expensive. The main disadvantage is that the process must be optimized for each type of resist and substrate, so spray coating can be time- and labor-intensive for developing a working process. Also, the formation of thin films is more difficult.