Photoreactive polymers are treated by exposure to microwave energy. A film of a photoreactive polymer (12), such as a photoresist, is applied to a substrate (10) and selectively exposed to ultraviolet light. The latent image produced is further cured or polymerized by treating the photoresist with microwave energy. Combinations of microwave and thermal energies are also used. The treated photoresist is then developed, producing a sidewall (17) that is vertical, and is improved by reduction of anomolies such as scum or a foot (16) at the base of the resist.