Hi everybody. I try to perform a e-beam lithography in order to create a hard mask of Aluminium with lines which have 1um or less of width.

I performed oxygen plasma cleaning and apply Surpass 3000 by ultrasonic vibration (I read that Surpass 4000 is better for maN, but we don't have possess it in our lab unfortunately).

After development the pattern lines are perfectly defined, and then I performed a hard bake at 120C for 10 minutes on the hotplate.

Then I performed Aluminium etching but all the maN pattern is killed.

H 3 PO 4 (95ml) + HNO 3 (5 ml)

Due I cannot afford Surpass400, should I use another primer, for example HDMS, in order to improve maN adhesion? Or should I keep using Surpass3000? How should I preserve the maN pattern during the Aluminium etching?

I will be grateful for any advice and discussion!