Some of our customers use alkali-sensitive aluminium substrates. This leads to problems if the metal surface should not be etched in this process.
In our product information, we recommend developer AR 300-26 for the development of AR-P 5320, our positive photoresist for lift-off applications. A few users however prefer to work with MIF-developers.
In order to prevent the above described stripping of the PMMA layer from the wafer, the use of adhesion promoters is strongly recommended. Helpful is also a tempering of the wafers at maximum temperature (if possible > 200°C)
Polyimides are produced by polycondensation of tetracarboxylic dianhydrides and diamines. For highest thermal strain only polyimides are suitable which contain aromatic building blocks in the polymer chain.
Aqueous-alkaline developers are subjected to ageing, due to an uptake of CO 2 from the air. Buffered aqueous-alkaline developers ( AR 300-26, -35 ) are more stable in this respect than developers of the AR 300-40 -series containing TMAH.