Chengyuan Xiao , are you keeping your spin coating parameters constant? (ie, static dispense, hold time, volume, ramp, adhesion promoter?)

https://www.ossila.com/pages/spin-coating

This guideline goes through a lot of detail on various spin coating principles and issues.

Best of luck!

Thank you for your kind answer Mr. Adam Ww,

I have also read that guide and it's very useful! Because we are using the antisolvent method, we will drop the antisolvent during the spin coating to wash away the original solvent in the solution. I am a bit worried that the halo is formed during the dropping process since the film is uniform without antisolvent dropping.

Best Regards,

Chengyuan

This kind of hole comes due to less hold time..and improper way of adding antisolvent.

You may increase the hold time before adding antisolvent.

Sometime if we adding antisolvent from far distance it makes holes.or the tip of micropipate touch the fto then also it may come...so when you add antisolvent try to add close as possible... without touching fto.

Thank you for your clarification Akshay Kumar Ray , I will check with a longer holding time.

Best Regards,

Chengyuan