Feature size limit analysis of lift-off metallization technology

Feature size limits for lift-off metallization patterns were evaluated both experimentally and by computer simulation. The mechanism producing smoothly sloped pattern profiles was clarified. It is shown that the slope angle can be changed from 20° to 70° with polyimide lift-off technology. Feature size limit for lift-off metallization patterns is determined by reverse mask topology, material characteristics, and the maximum incident angle of the metallization deposition, though it is independent on metallization thickness. In a sample application of the technology to fabrication of interconnections on rugged LSI surfaces, the minimum pitch of the polyimide lift-off metallization patterns is estimated to be 2.6 µm.