[labnetwork] Has anyone using thicker than 200nm HSQ for EBL patterning?

Mon Apr 1 10:48:04 EDT 2019

Mason:
I started storing HSQ in liquid N2 (make sure you crack open the lid when you take it out, some N2 will get into your bottle) and it works great. I started doing this at Mike's suggestion and completely agree with him.

We had been decanting from the Dow, 100ml, containers to 1.5 mL cryo tubes in a glove box before we started with the liquid N2. This worked well for us so we continued doing it, though the glove box may not be necessary (segregating the HSQ from solvents, especially NMP is the goal). We then store the cryo tubes in a -60C fridge in the lab for convenience (little room for a dewar in the lab).

The dry HSQ is advertised to have a very long shelf life if stored in a dry environment. I have not tried to use it yet, but have some on hand.

HSQ delivery times, from Dow, are variable. Last time I ordered 6% in November, it arrived mid-March.

Regards,
Mark K Mondol
________________________________
From: Mason Risley [mrisley at andrew.cmu.edu]
Sent: Monday, April 01, 2019 10:23 AM
To: Michael Rooks; Mark K Mondol; labnetwork at mtl.mit.edu
Subject: RE: [labnetwork] Has anyone using thicker than 200nm HSQ for EBL patterning?

Thanks Michael, that is good information. I had it in mind to switch to cold storage and those HC LN2 refrigerators seem like a great way to go.

I’ve also heard it helps to dispense the HSQ into the 4mL vials while in a nitrogen glove box to prevent exposing the stock solution to oxygen or humidity, do you guys do the same or do you just transfer from the stock bottle under ambient conditions in the clean room before freezing?

From: Michael Rooks <michael.rooks at yale.edu>
Sent: Monday, April 1, 2019 10:16 AM
To: Mason Risley <mrisley at andrew.cmu.edu>; Mark K Mondol <mondol at mit.edu>; labnetwork at mtl.mit.edu
Subject: Re: [labnetwork] Has anyone using thicker than 200nm HSQ for EBL patterning?

You should be storing HSQ in liquid nitrogen. Check out the presentation
https://nano.yale.edu/sites/default/files/files/hsq_frozen(1).pdf

We have been doing this for five years, and it works great. Five year old HSQ is just as good as fresh HSQ.

Getting reliable deliveries from Dow-Corning is an issue, but at least we don't have to worry about shelf life anymore.

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

On 04/01/2019 10:08 AM, Mason Risley wrote:
Hi Mark,

Thanks for mentioning about the dry HSQ, I didn’t realize that was available. Do you know if dry HSQ has a better shelf life than the standard XR1541 in MIBK? That’s a challenge my lab is always fighting that our HSQ ends up gelling or solidifying before we use the entire bottled, I’m wondering if by prepping smaller quantities from dry HSQ as needed would be a better way to manage shelf life.

Mason Risley
Process Development Engineer
Clair and John Bertucci Nanotechnology Laboratory
5000 Forbes Street, Pittsburgh PA 15213
nanofab-staff at lists.andrew.cmu.edu<mailto:nanofab-staff at lists.andrew.cmu.edu> | http://www.nanofab.ece.cmu.edu/
ph: 412.268.5419 | cell : 505.795.4805

From: labnetwork-bounces at mtl.mit.edu<mailto:labnetwork-bounces at mtl.mit.edu> <labnetwork-bounces at mtl.mit.edu><mailto:labnetwork-bounces at mtl.mit.edu> On Behalf Of Mark K Mondol
Sent: Saturday, March 9, 2019 5:06 PM
To: Michael Rooks <michael.rooks at yale.edu><mailto:michael.rooks at yale.edu>; labnetwork at mtl.mit.edu<mailto:labnetwork at mtl.mit.edu>
Subject: Re: [labnetwork] Has anyone using thicker than 200nm HSQ for EBL patterning?

As usual I agree with Mike, but have to chime in anyway. Applied Quantum Materials in Canada offers dry HSQ, which you mix with MIBK to make a solution. I just got some and haven't used it yet, but others have. As it is dry you can make whatever dilution you want to achieve thicker films.
________________________________
From: labnetwork-bounces at mtl.mit.edu<mailto:labnetwork-bounces at mtl.mit.edu> [labnetwork-bounces at mtl.mit.edu<mailto:labnetwork-bounces at mtl.mit.edu>] on behalf of Michael Rooks [michael.rooks at yale.edu<mailto:michael.rooks at yale.edu>]
Sent: Saturday, March 09, 2019 8:50 AM
To: labnetwork at mtl.mit.edu<mailto:labnetwork at mtl.mit.edu>
Subject: Re: [labnetwork] Has anyone using thicker than 200nm HSQ for EBL patterning?

Multiple-spins seldom produce good results. It's easier to use a thicker solution of HSQ. Of course you can buy thicker HSQ, such as Fox-16, but if you are in a hurry you can thicken the 6% HSQ (well, any resist really) by bubbling nitrogen through it. Just put a tube in the bottle and blow in some dry nitrogen. The solvent will evaporate, and the bubbles will keep the solution agitated, so a skin does not form on the surface. No need to be precise about the solution. Just keep bubbling until you get the thickness you want.

------------------------------------
Michael Rooks
Yale Institute for Nanoscience and Quantum Engineering
nano.yale.edu

On 3/8/2019 10:02 PM, Zhao, Mengdi wrote:

Hello everyone,

I am trying to spin 350nm HSQ by double coating XR1541 6% at 2000rpm and bake at 80C between coating. However, HSQ thickness measured by reflectance spectrum actually get thinner after the second spin and bake. I wonder if the HSQ still get dissolved again during the 2nd dispense even with 80C bake for 4min after the first coating. Any suggestion on getting over 200nm HSQ spin coated on Si?

Best regards,

Mengdi

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