[labnetwork] Long prebakes of PMMA for EBL

[Michael Rooks]

I have never seen a difference between baking a few minutes or a few 
years. Once the solvent is gone, it's gone. The required dose is 
insensitive to the bake time.

Outgassing of the solvent is not a problem. Also, outgassing of low 
molecular-weight pmma is not a problem. We are not using UHV systems for 
lithography. Systems that use electrostatic deflection (JEOL) are 
slightly sensitive to polymer deposition on the deflection plates, but 
system diagnostics keep track of distortion and warn the operator when 
cleaning is necessary (which is, hardly ever).

--------------------------------
Michael Rooks
Yale Institute of Nanoscience and Quantum Engineering
nano.yale.edu <http://nano.yale.edu>



On 03/14/2017 11:39 AM, Lino Eugene wrote:
>
> Dear colleagues,
>
> I would like to have inputs from you regarding long prebakes of PMMA 
> before e-beam lithography. I have always used 180 C for 90 s on 
> hotplate as recommended in the technical data from Microchem. However, 
> I have seen some SOPs where the prebake is longer, between 3 min and 
> 20 min. I am wondering if there is any concern about the anisole 
> solvent degassing in the vacuum chamber and if some EBL systems are 
> more sensitive than others.
>
> Also, I am wondering what the impact of a longer prebake has on the 
> EBL process. I would expect a longer development time. What about the 
> dose?
>
> Thank you!
>
> **
>
> *Lino Eugene, Ph.D., Jr. Eng.*
>
> Quantum NanoFab
>
> University of Waterloo
>
> 200 University Avenue West
>
> Waterloo, ON, Canada
>
> N2L 3G1
>
> Ph: +1 519-888-4567 #37788
>
> Cell: +1 226-929-1685
>
> Website:https://fab.qnc.uwaterloo.ca/
>
>
>
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