In normal nanofabrication exp., we used to apply PMMA as triple as the final thickness of the required nano-structures in EBL process.
My question is , what will happen if we use a higher thickness of PMMA regarding to the final nanostructure thickness? for example, nano-structures with 50 nm thickness and we add PMMA of 350nm instead of 150 nm? will we still be able to get the required structures? Do we need to increase the dose in that case?
thicker the PMMA lesser is the accuracy in etching by EBL particularly towards width.
You should pay attention to the aspect ratio of your structures. If the aspect ratio is too high, the structure can collapse. The maximum aspect ratio you can have depends on the lateral dimension of your pattern and is not linear. A 50 nm line width with a PMMA thickness of 350 nm is challenging, you should use a special way to develop your structures. The dose is changing with the thickness but not much, higher resolution structures require higher dose.
Hi all,
Thanks for your responses
In my exp. I will use high dose to get fine structures.
Maybe I'm going to try with higher development time with such thick PMMA and I hope it may work!
Thanks again
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