Dear All i am working on Si etching using TMAH. I am looking for AL protection. In order to achieve it, i am adding Silisic acid (1.4wt%) and Ammonium persilpahte (0.7wt%) in 5 Wt% TMAH. With this etchants, In actually experiment, AL layer is getting etched. Can be one suggest me, how to achieve AL protection in TMAH with acceptable Si etching rate. - Abhay joshi Universaity of Pune.