Hi, all

I have experienced a problem of photoresist peel off during the Nickel
e-beam deposition (by CHA machine) process for lift-off purpose. The
picture is shown:

http://picasaweb.google.com/tangweipku/PRPeeledOffDuringEBeamDepositionOfNi#5441
568465466565330

 I am guessing the problem comes from the residual stress in the as
deposited Ni film.  The deposition rate is 3A/s and final thickness is
150nm. The PR is 1.4um AZ5214E and the pattern is made by
image-reversal process. The SiO2 wafer have been primed in HMDS for
10min before spin coating.  I have tried several method below but NONE
of them solve the problem:

(1) hard bake at 130C for 5min after development (the undercut has
been compromised a lot during the hard bake process)

(2) UV bake for 35min

I am wondering is there any way to overcome this problem by:
(1) adjust the deposition parameter to produce less stress
(2) treat the photoresist to increase the adhesion with the substrate
(I have already primed the wafer with HMDS before coating)

Any comments or suggestions are appreciated.

Thanks,

Wei

--
Wei Tang
Department of Materials Science and Engineering, UCLA
Cell: 310-357-0158
Website: http://tangweipku.googlepages.com