I want to coat polymer film on BK7 glass substrate using the spin coating technique (I have no prior experience). The thickness of film is around 500nm. I tried many times to adjust the speed and rotation time, but the film seems to be several micrometers. Is it feasible? What should I pay attention to? Or do you have any beneficial suggestions? Thanks a million.
There is no problem to deposit polymer layer with thickness of 500 nm. Have in mind that the film thickness decreases with the decrease of concentration and increase of spin-on rotation. For example to deposit 500 nm PMMA film I use solution with concentration of 7wt.% and rotation speed of 3000 min-1.
The paper below may be useful, it covers a few polymers (PS, PMMA,) and shows the effect of varying concentration, spin speed on film thickness.
D. B. Hall, P. Underhill, and J. M. Torkelson, “Spin coating of thin and ultrathin polymer films,” Polym Eng Sci, vol. 38, no. 12, pp. 2039–2045, Dec. 1998.
I tried to decrease the concentration by using acetone solvent. After the ultrasonic processor for blending the mixture of polymer and acetone, the solution becomes milky. I thought the solution should be transparent, seems abnormal (the polymer is transparent). Dirt contamination?
Firstly, you must know the type of thin polymer film you need to be deposited. To control the thin polymer film, i suggest the sol-gel spin coating or dip coating. The parameter you need to control are the concentration of sol solution, the speed rate and also the time of rotation. If the speed rate is too low, the thickness will be thicker compare if you set the speed rate is too high. When the speed rate too high, the sol solution will spread more out from the substrate and leave less of the sol solution and form very thin layer of film. If the thickness are very thin less than 100 nm, you can repeat the spin coating at the same speed rate many time untill you obtain the thickness around 500 nm. Hope this suggestion can be useful for your research.
In add, may you can tried to slow rotation first in 5-10 s, after that you can increase rotation. But the way its depend your solution concentration.
Thanks for all of your good suggestions.
The process has been divided into two steps: slow speed and high speed. And if I drop polymer on the substrate before slow rotation, then the film looks good (tried many times and only one time is successful); but if I drop polymer during slow rotation, then the polymer spreads to one side, I am sure I dropped polymer onto the center of rotation.
You should drop the polymer first and than spin on. If the solution is too viscous than high speed rotation is preferable. Also try to increase the amount of the drop. For example for 24 mm x 36 mm substrate I use 0.3 ml. But again have in mind that all this depends on the solution
Dear all
I read your valuable comments and got very useful information. By the way did any one know about the spin coating of conductive polymer such as PANI on steel substrate. If any publication could be useful.
Pill be grateful if anybody will guide me in this purpose.
I guess you, to the fist time make sure that your have very soft solution. some method can help you to found solution like that. And the next step you coat from the low rpm aim high rpm, depend your solutes. After that with quickly, you can annealing in the air but if you want you can try in the vacuum it also depend melting point your material. But, I think you not needs to do in the long times. Just several minutes.
If you think you need to more the thick, you can reload with the same direction.
Good luck
Please fin attached. Go through below links for details.
http://onlinelibrary.wiley.com/doi/10.1002/app.43532/full
http://www.sciencedirect.com/science/article/pii/S0032386116301227
Hello,
This answer might be out of date but we never know. When my PMMA/Acetone solution tend to be milky ,I used to filter it with 0.45 microns pores filters mounted on a syringe. The filtered solution is cristal clear and I still manage to get nice thin films by spin-coating. The problem is that you're not really sure about the exact polymer concentration in the solution anymore as the polymer aggregates that make the solution milky are blocked in the filter.
Did you finally succeed? If yes with what conditions?
Cheers,
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