Subject: Re: HSQ <<< Is there a better alternative for HSQ. (Threads on HSQ processing... )
From: "James W. Conway" <>
Date: Tue, 23 Oct 2012 09:33:16 -0700

Thanks Mike,

I didn't realize you could keep it in the freezer!  I take it the little bottles are Polyethylene or PVC and never glass.....

In our lab we decant into 2.5 ml PE syringes with a 10 mm PVDF or PTFE 0.45 um filter.  The time it takes to take the source bottle back is sufficient to warm the small volume to ambient for the spin.

I think the 'Big Book of HSQ' idea would be grand and will explore to see if we can start this on the SNF swiki or start a new one on the normal wiki channels we all contribute to...



On 10/22/2012 5:27 PM, Michael Rooks wrote:
This is all very good advice.  I'd just like to chime in saying that we store HSQ in the freezer.  Our freezer is about -27C, which does not freeze MIBK.  Colder is better, if you want to slow down chemistry.  We split the HSQ into little 4 ml bottles which can be warmed in just a few minutes in your hand.  Unless you're a vampire.

Well. Someone ought to write all this down in The Big Book of HSQ.  Is there a wiki for resist?


"Michael Rooks"<>
Yale Institute for Nanoscience and Quantum Engineering

On Oct 22, 2012, at 6:37 PM, James W. Conway wrote:

Hello All,

Sorry to chime on this old thread, now weeks old.

We also purchase through Ellsworth Associates.  They directly drop ship from Dow Corning to us.  Charge us about 33% more than we paid ordering direct.   Dow will no longer direct ship this product to anyone.

I have found the XR-1541 blend to be more stable is bottled storage and if cared for and KEPT COLD at 5 degrees C and not frozen will store three times longer than their stated expiration dates:
  • The old FoX blend was less stable in bottled storage, and exhibits decided exposure shift when stored in thin films on substrates longer than 14 days. Once a natch has died it gelates and you can see chunks of glass on the inside of the Polyethylene bottle, presumably hydrolyzes.  I have an old dead batch in the fridge from 2008 and it just died the last few weeks.  Maybe someone using it for Spin-On-Glass left it out.

  • Exposure response and low sensitivity is the same as the FoX-12 product, with the same albeit normal proclivity to scum or foot in areas adjacent to exposures to varying degrees from Exposure Proximity Effect ; which can be reduced but not eliminated by various development methods and/or baking temperatures.  The literature is full of various treatments but the material is still difficult to work with and scums and foots at any exposure other than just above the initial fully cross linked dose. 

I would put forth it is best to not mess with Dow and attempt to hack a replacement as they protect their patents carefully.  I have talked with two companies this year on alternatives to HSQ and they both declined to pursue this market. 

I have two baseline processes defined both single layer negative tone HSQ for RIE and direct write patterns for NIL stamps, and another for  Dual layer negative tone HSQ over PMMA for Metal Lift Off, RIE hard masking, and slotted metal films for plasmonic waveguides:
Dual Layer Negative Tone process for plasmonic slot waveguides and Metal Lift off structures. Pending publication for EIPBN 2013...

Hope to see you all before NASHVILLE next June!

All the Best,


On 10/19/2012 5:17 PM, Michael Rooks wrote:

Dow-Corning still makes HSQ (XR1541) but now they sell it through vendors who know how to handle the paperwork.  
We buy HSQ from Ellsworth Associates (Jennifer Pence <>), but it's shipped directly from Dow-Corning.

I agree that we need a second source or a good alternative.  I suggest an X-Prize contest for a do-it-yourself HSQ resist.  

Speaking of overpriced polymers, I now have a cheap alternative to Espacer (for HSQ on insulating substrates).  Check it out on my web page.


"Michael Rooks"<>
Yale Institute for Nanoscience and Quantum Engineering

On Oct 19, 2012, at 5:56 PM, Richard Tiberio PhD wrote:

hello to all,

Here is another quick reply:     <<< James and the HSQ team can help with this discussion with more details.

Trade-Off:      HSQ has great resolution,  which keeps up the motivation despite HSQ's terrible reliability.

Worse:     Buying HSQ has turned into a tragic opera,   ( add your own reference here. )
                The original vendor sold HSQ as a Flowable-Oxide,  hence the name FOX.
                (  for example Dow Corning for the HSQ (XR1541),  )
               Maybe Dow Corning grew tired of so many universities calling to order tiny 100 milliliter volumes.

Worst:     I understand that Dow has sold the rights to a smaller vendor.......and the new vendor service is inferior to Dow.

My Observation:   
*   HSQ is great in certain applications,  
*   many publications show a wide range of dependencies, lag-times, humidity,   etc etc. 
*   it has poor shelf-life  
*   the availability is erratic.  

Opportunity:    We all wish someone would invent a substitute for HSQ.  

James and/or  Mike,  is the situation as bad as I see it ?   better ?  worse ?  

Rich Tiberio

From: "J Provine" <>
To: "Roger Fabian Pease" <>
Cc: "Richard Tiberio PhD" <>, "James W. Conway" <>
Sent: Friday, October 19, 2012 2:27:14 PM
Subject: Re: HSQ

For just the coating, I could help. Or James. 

On Friday, October 19, 2012, Roger Fabian Pease wrote:
ok Thanks. 
Rich T in SNC doesn't seem to fancy it.
Who in SNF is the right person to talk to to get a couple of wafers coated?

On Oct 19, 2012, at 12:27 PM, J Provine wrote:

in snf there is hsq, it can be deposited, exposed, and developed in snf or at snc.

On Fri, Oct 19, 2012 at 9:40 AM, Richard Tiberio PhD <> wrote:
to all,
fast reply:     over here in SNC, in the JEOL area.
HSQ on hand ?         = NO,  it has a very short shelf-life,  expensive, delicate,  easy to make mistakes.
HSQ spinning            = yes
HSQ exposing           = yes
HSQ developing        = yes
Rich T

From: "pease" <>
To: "J Provine" <>, "James W. Conway" <>, "Richard Tiberio" <>
Sent: Friday, October 19, 2012 9:12:25 AM
Subject: HSQ

Do we have the capability for depositing, exposing and developing HSQ? 
If not, who does?

On 10/18/2012 4:30 PM, Kyunglok Kim wrote:
> Dear labmembers,
> I'd like to use 6:1 BOE to etch a 1um thick LTO deposited at 400degC.
> If 6:1 BOE etch rate is too aggressive, I also have a plan to use 50:1 
> HF instead of it.
> Would you please let me know the average etch rate of both of them?
> I really appreciate your help!
> Best,
> Kyunglok Kim
> PhD Candidate
> Electrical Engineering
> Stanford University