Single-Step Optical Lift-Off Process

A process is described that allows the use of the lift-off metallization technique with ultraviolet exposure of a single layer of ®AZ-type photoresist. The process consists of soaking the resist layer for a predetermined time either in chlorobenzene or other aromatic solvents such as toluene and benzene before or after exposure. After development, resist profiles with overhangs suitable for lift-off metallization are obtained. It appears that removal of solvent and low-molecular-weight resin from the ®AZ resist may be responsible for the observed differential development rates. In addition, the soak time and temperature behavior indicate a diffusion-type process.