reticulation on ZEP using Lampoly?

James W. Conway jwc at snf.stanford.edu
Tue Oct 4 10:24:44 PDT 2011


Hello to such a long list of people...

I have seen reticulation of ZEP-520 at resist application when applying 
to oxides and nitrides long before, but your result is a particularly 
spectacular one.  Thank you for the excellent SEM image.
If you follow my standard ZEP-520A Process you should not see this type 
of problem.  But if your sample is not perfectly clean you will often 
see this problem, based on many users experience.

Questions:

How was the SOI substrate cleaned before resist application?

Did you employ a HMDS prime step or not?

Did you measure the resist thickness using the nanospec?  n = 1.54 using 
program 10.

Please confirm this was present as applied and not after any RIE etch 
treatment.  The reticulation you mention could also be Polymeric PTFE 
material if you employ CF4 or other Florine source during RIE.
RIE can really beat up this material if you don't perform an extended 
pump down of the chamber before processing as that water vapor from 
adventitious sources in the chamber breaks down to O2 during RIE.  Also 
best to avoid O2 in the processing.

Once exposed how did you develop out.


     Last week upon reports from Kelly and one other user of dosage 
changes I spun ZEP-520A onto Silicon wafers during last Tuesday's 'Take 
a Spin with Me' class.  I have done thickness measurements and inspected 
the batch bottle and so far found no problems. 268 -  270 nm films were 
deposited spinning at 8000 rpm with uniformity variations on the order 
of 4 to 10 Angstroms (0.4 to 1 nm) across a 100 MM SEMI WAFER.
I am exposing this material in test today and next week.  So before and 
after exposure I will perform an careful optical microscope inspection 
and report back to this list..
FYI the current bottle of ZEP  is soon to run out and I have a new batch 
in the house ready to go.

Thank you,

James

On 9/29/2011 5:41 PM, Kyeongran Yoo wrote:
> Hello Raith, JEOL, and Lampoly users,
> I have reticulation issue on my ZEP520 pattern after using Lampoly.
> I am wondering if you have such a problem.  If so, how did you solve 
> this issue?
> Please take a look at the attached file and let me know your comments.
> thank you very much and have a nice day.
> best,
> Kyeongran



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