Spin Coating PEDOT PSS

[prix27]

I have got a Si wafer 4" in diameter. I am cleaning it using Piranha solution. I am spin coating water soluble PEDOTSS on top of it with static dispensing ( I am dispensing the material around 5ml before the spin starts). The material I deposit covers the substarte completely. I am spinning at the speed of 4000 rpm for 1min.

The issue is I am always getting comet tail defect or streak through out the wafer after spinning.

Before spin coating I am using syringe filter to filter out the particles from the solution. I am using a laurell 400 lte spin coater without a fragment adapter. I am just lying the wafer on chuck as the wafer is too big.

Please help. Your suggestions are highly appreciated. Please let me know IF I am doing anything wrong.

Best Regards
Prix

 

[IRstuff]

I suggest you Red Flag mark it to be deleted and moved to forum332, which is probably more active and more likely to respond to questions like this.

TTFN
faq731-376