Semiconductor etching preparation method - uses second UV exposure and thermal hardening to reduce blurring

摘要

When semiconductors are made by etching a substrate (1) through a film mask (2,6) the unwanted areas (5) of the mask are first removed by alkaline development after ultra-violet exposure (4). One problem with this method is that the etching agent also damages the edges of the mask resulting in poor definition or blurring. A second exposure to ultra-violet rays, with a wavelength of 330 to 450 nm, gives the remaining mask fine times the resistance to etching of a mask which has not received this second exposure. The substrate and mask are then put into a 125 deg.C. infra-red oven, for 5 minutes to provide further hardening of the film.