A single layer negative tone lift-off photo resist for patterning a magnetron sputtered Ti/Pt/Au contact system and for solder bumps

At first, the capability to obtain an undercut pattern and the thermal stability of the resist ma-N 1400 is demonstrated in the lift-off patterning of magnetron sputtered thin three layer contact system Ti/Pt/Au. Temperature of the substrate during sputtering was measured time-resolved using a thermal couple. Secondly, an example to achieve AuSn solder bumps of 7.5 μm diameter by a combination of sputtering and metal evaporation using the lift-off resist ma-N 400 is given. Regarding the further miniaturization of electronic devices, this process is a cost-effective method to achieve solder depots for flip chip bonding of ultra thin chips.