Some of our customers use alkali-sensitive aluminium substrates. This leads to problems if the metal surface should not be etched in this process. While our MIF-developer (AR 300-40 series) and developer AR 300-26 strongly attack aluminium surfaces, the metal surface remains largely unchanged if developer AR 300-35 is used. Quite likely, a passivation layer is formed on the metal surface which reliably protects the metal from further attack. The aluminium foil survives the contact with AR 300-35 for hours basically unchanged, while the foil in contrast quickly dissolves in AR 300-47.
It furthermore became evident that also concentrated variants of AR 300-35 can successfully be employed as remover. A large number of resists are only difficult or impossible to remove in organic removers after an application in high-temperature processes, e.g. sputtering, ion etching, or also ion implantation. The utilisation of efficient alkaline removers was so far however only possible to a limited extent if alkali-sensitive substrates like e.g. aluminium were used. Stronger variants of AR 300-35 now demonstrated similarly good cleaning results as our TMAH-based alkaline remover AR 300-73, and without attacking aluminium surfaces significantly.