Dear Navid,

This might be due to oxide formation on your last Cr layer, I would definitely recommend HMDS priming, or an acid attack to remove the oxide layer. it might reform immediately (so HMDS first, obviously)

please confirm if it works, I'm curious.

Suggestion of good ref for your mems issue:

https://www.microchemicals.com/micro/tds_az_nlof2000_series.pdf

https://memscyclopedia.org/

I agree with Hugo Salmon ,

However, first can you provide your protocol? There may be some easier procedures to try first. For example, you could try a quick UV-Ozone treatment prior to resist coating.

I also attach a useful Lithography Troubleshooter by MicroChemicals

Jules

Thanks all for your replies:

@ Thomas Breuer

My process steps are as follows:

1-I clean my samples in Acetone (with ultrasonication)+ IPA (ultrasonication) for about 5 minutes each.

2-Dry in Nitrogen flow

3-preheat for 3 minutes at 120 to evaporate moitures.

4-spin coat nlof2035

5-bake nlof2035 at 110C

6-expose

7-post bake and develop nlof2035.

The photoresist has poor adhesion to nlof2035 and slides over.

@Hugo Salmon & Jules Lloyd Hammond

I guess you are right, Chromium oxide absorbs water vapors and leads to poor adhesion of the photo-resist.

I did hydrogen plasma cleaning to remove oxide layer and also tried HMDS and it helped to increase the adhesion.

I didn't tried quick UV-Ozone treatment, have you guys have had any experience on this?