Dear all,
I am currently working on BTO thin films deposited on Si/SiO2/TiO2/Pt substrates via chemical solution deposition (Sol-gel + spin coating).
How can I leave some part of the bottom electrode uncovered during the spin-coating?
I have tried with the tape method but it´s not always successful, is there another way?
Thank you for the help.
Regards,
Federica
Dear Federica Benes , you could try with some photoresist you have on hand. Basically it means spin coat the photoresit, with a thin layer (high speed) so that the film will be as thin as possible. Then you can make a cheap mask with paper or aluminum foil by cutting some windows with the shape and size of your electrode. Cover the substrate with the mask and expose it to UV light. Note: if your photoresist is positive tone, the exposed area will be developed , leaving just the protected area (the electrode area). If your resist is negative tone, the exposed areas will remain after development, so in this case you should expose the area on top of your electrode.
Once you have your electrode area protected you can spincoat your sol-gel. The thinest the photoresist layer protecting the electrode the less it will interfere on sol-gel spread ove the substrate.
Finally, remove the protective photoresist by disolution with a proper solvent (it must disolve the resist, but not your sol-gel).
Hope it helps.
Maybe you will find etching the BaTiO3 film to be a difficult task by chemical methods to expose the bottom platinum electrode. But if you are able to find an etchant, then it will be very convenient.
I would simply scratch the BaTiO3 film at two different places carefully with a pointed tip. Then put some air drying silver paint on the scratch. Take a multimeter put the two probes on silver paint dabs on the two scratches. If they are contacting the platinum film underneath. Thereby you are able to make a contact to the bottom electrode.
@Federica Benes,
If you could acess to a laser micromachining tool, that is the best way to remove the BTO layer and leave your electrode uncovered by the BTO films.
Alternatively, the tapes are very often used in the laboratory scales. You have to use a special tape such as a thin, tolerant to the higher temperature and chemicals.
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