Dear Sirs and Madams,
We are having an issue with adhesion between ma-N 2403 EBL photoresist and borofloat glass. We have tried spincoating HMDS but it proved unsuccessful.
SurPass was suggested (cationic primer) but we do not have access to it - does anybody know its composition?
Any suggestions are welcomed. Thank you in advance.
Jules.
Can you vapor prime instead of spin the HMDS? Etch the glass in piranha before priming. You may need to do some optimization for the parameters of the resist as well. Some resists are very sensitive to humidity as well as adsorbed water on the substrate so a dehydration bake may also improve adhesion.
Have you ever plasma O2 on the glass surface prior to resist coating? Plasma O2 may improve adhesion between resist and glass surface.
I'm more worried on the charge built-up during e-beam exposure on insulating substrate such as glass. I did sputter coat the glass substrate with 5 nm tungsten prior to resist coating to supress charge during e-beam exposure as well as resolve adhesion issue.
I agree with the need for a dehydration bake. I would try 120 C for 5 minutes.
O2 plasma can also help. Just a 30 second treatment with ~15 volts can help a lot. Exact settings will depend on your equipment.
Andrew H. Cannon, Ph.D.
researchmicrostamps.com
Thank you all for your suggestions.
A dehydration step (5 minutes @ 200 oC on a hotplate) improved things somewhat. I did try a very thin < 5 nm Cr layer before resist spinning which drastically improved adhesion and allowed the dose to be reduced so I think that may be the way forward in the long-term (I will need to get a good undercut when I etch that final layer in the final step as an electrode will be patterned on top of it).
@Ron - We don't currently have a system for vapour priming but I may investigate a DIY system for future work.
@Khairudin - I did use several different (metallic) anti-charging layers after the resist spinning to improve things.
@Andrew - Thank you for the tip, I may try this in the future.
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