Dear all,
I am currently spin-coating a 10 wt% polystyrene (Mw = 280,000) solution in anisole onto a silicon wafer. The wafer is pre-cleaned using acetone sonication followed by isopropanol sonication, each for 5 minutes. The spin-coating parameters are:
- Speed: 2000 rpm
- Duration: 1 minute
- Acceleration: 500 rpm/s
I have experimented with different coating volumes, but all resulted in the same surface appearance (see attached image). The procedure follows an exact protocol from a published paper, yet the outcome seems inconsistent with the expected results.
Could anyone provide insights into potential causes for this issue? Any suggestions or troubleshooting advice would be greatly appreciated.
Thank you in advance for your help!
Dear Yuewen Jia,
Enhancing the uniformity of your spin-coated polystyrene films can be achieved by increasing the spin speed, which promotes faster solvent evaporation and results in thinner, more uniform coatings. Additionally, performing an oxygen plasma treatment on the silicon wafer increases its surface energy, improving wettability and adhesion of the polystyrene film.
Best regards,
Alvena Shahid
Alvena Shahid Hi Alvena Shahid, thank you very much for your suggestion! I will try performing an oxygen treatment.
Your film is clearly not wetting the surface. Anisole should be hydrophobic, I think. Bare silicon as such is also hydrophobic but its oxide is hydrophilic so you need to try to get of this for wetting, e.g. by an ammonia or dilute HF dip (dangerous!).
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