Hi, all,

  The structure of our device composed of silicon/Patterned PMMA(~200
nm)/ALD Al2O3 (~40 nm). I have tried to dip the device in acetone to do
lift-off but the Al2O3 layer on the entire substrate surface does not
lift-off.  It seems that either acetone can not penetrate the Al2O3 layer or
the PMMA layer is hardened.  The deposition temperature for ALD  Al2O3 is ~
150 C which  should not  be high enough to harden PMMA.

  Does anyone have any suggestions on the lift-off process?

  Thanks a lot.

Best regards,

Jun