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Ask the Staff
ruchit.mehta.1
2012-02-17 11:54 AM
metal liftoff from optical lithography on graphene
I am having trouble lifting off Ti/Au (5nm/50nm) from graphene surface using optical lithography. I use AZ1518 (6000rpm 55sec / 85C 5min softbake) to pattern hall bar structures of 12um x 40um and have no liftoff after hot PG remover soak for 2 hrs. I have used Lesker as well but liftoff does not work on graphene(poor adhesion) but works on SiO2. The problem is I need in-situ liftoff and cannot use force from acetone bottle or gun as this damages graphene and peels it off. Any ideas as to if the issues are with photoresist or otherwise. Thanks!
aamer.mahmood.1
2012-02-17 12:19 PM
Lift off
Ruchit,
The key to a good lift off is a clean break between wanted and unwanted metal. This is usually achieved by providing a negative slope profile of the sacrificial photoresist. As we discussed a few days ago, did you try getting such a a lift-off friendly profile using CBZ with the PR. I have had the CBZ work quite well with 1518 on SiO2 but not on Si surface. Alternatively, you should use a 2-step Lift-Off Resist (LOR) based process. Feel free to contact me for more details about LOR. |
