Specialized photolithography equipment and thick photo resist for wafer level packaging and wafer bumping

In advanced packaging, the demands on photosensitive material, exposure and coating equipment differ from VLSI technology. While in VLSI technology sub-micron features have to be opened in very thin resist layers, wafer bumping or wafer level chip size packaging requires only a resolution of a few microns, but in thick photo resist. Patterning (bumping and redistribution) in the very thick resist and photosensitive insulating layers are, however, challenging. In order to meet the special requirement in wafer bumping and chip size packaging on wafer level, special equipment and photosensitive materials have been developed recently