XR-1541 (HSQ) ebeam resist

Mary Tang mtang at stanford.edu
Fri Dec 15 17:50:31 PST 2006


Gosh, I wish EVERYONE would write requests like this.  HSQ has been 
approved and used in the lab.  Mahnaz -- is this used only at the 
headway or can it be used at the laurell as well?  (My concern is that 
HSQ is like SOG -- and we only allow this at the headway because if not 
cleaned immediately, it will harden and become impossible to remove.)

We should ask what kind of developer will be used -- I think ordinary 
TMAH or related basis developer is often used.  But good to be sure, 
just in case.


Alexander Driskill-Smith wrote:
> We would like to use HSQ negative ebeam resist in our experiments at 
> SNF. I don't think it has been used previously at SNF; however it is 
> commonly used in research laboratories elsewhere for high-resolution 
> ebeam exposures. Please would you review the material and processing 
> details below and let me know if you need any further information. I 
> ordered 125 ml of the material recently and it arrived at our site in 
> Milpitas today. It needs to be stored in a refrigerator (0-10 C) so I 
> would like to transfer it to the refrigerator at the SNF facility as 
> soon as possible.
> *1. Contact information*
> Coral login: drisk
> Other contact information listed below.
> *2. Material*
> Commonly known in the lithography community as HSQ (hydrogen 
> silsesquioxane).
> For several years, HSQ has been available from Dow Corning under the 
> name FOx (short for Flowable Oxide) since its initial application was 
> as a spin-on glass.
> More recently, a special filtered version of HSQ for ebeam resist 
> applications was introduced by Dow Corning under the name XR-1541.
> MSDS for XR-1541 is attached.
> *3. Manufacturer*
> Dow Corning Corporation, South Saginaw Road, Midland, Michigan 48686
> Telephone (989) 496-6000
> Website www.dowcorning.com <http://www.dowcorning.com>
> *4. Reason for request*
> The performance of HSQ as a negative resist is unmatched by any other 
> material that I am aware of. It has essentially unlimited resolution 
> (<10 nm has been demonstrated, and resolution seems limited only by 
> the resolution of the ebeam spot size). After ebeam exposure, it 
> essentially turns to glass, and therefore has far superior resistance 
> to the ion milling and etching steps in our process when compared with 
> standard polymer resists. It also has excellent mechanical strength, 
> which means high resolution structures can be defined with high aspect 
> ratio (>10:1 aspect ratios have been demonstrated), again useful in 
> our application.
> One of its downsides is the high exposure dose (>500 uC/cm2 for 
> large-area features), but this is not an issue in our application due 
> to the very small pattern density on our wafers. It is also claimed to 
> degrade over time, but in my previous experience the useful lifetime 
> has been 1-2 years or more, provided it is stored in a refrigerator. 
> Its contrast does degrade over time, but this is not an issue for our 
> isolated device patterns (unlike dense patterns, which would suffer 
> with reduced contrast).
> *5. Process Flow*
> Coat XR-1541 resist: Headway, Laurell or ebeam bench
> Post-apply bake: hotplate
> Ebeam exposure: ebeam or raith
> Post-exposure bake: hotplate
> Develop: wbmiscres
> Etch underlayer: drytek 1 or 4
> Ion mill MTJ device: mrc or outside SNF
> Oxide deposition: sts or outside SNF
> Spin-on glass coating: Headway or Laurell
> Etch oxide/SOG: drytek 1 or 4 or pquest
> Etch underlayer: matrix
> Top lead deposition: metalica or innotec
> *6. Amount and Form*
> 125 ml plastic bottle of liquid.
> We will probably decant a small amount of the resist into a smaller 
> plastic (not glass) container so that the bulk of the material 
> can remain in the refrigerator at 0-10 C with minimal temperature 
> cycling up to room temperature.
> *7. Storage*
> Storage group L
> Needs to be stored in a refrigerator (0-10 C)
> Must NOT be stored in a glass container
> *8. Disposal*
> Plastic container for flammable liquid waste
> Alexander A. G. Driskill-Smith
> Grandis, Inc.
> 1123 Cadillac Court, Milpitas, CA 95035
> Telephone: (408) 945-2156
> Facsimile: (408) 945-2161
> Cellphone: (408) 807-4402
> Email: alexander.driskill-smith at grandisinc.com 
> <mailto:alexander.driskill-smith at grandisinc.com>

Mary X. Tang, Ph.D.
Stanford Nanofabrication Facility
CIS Room 136, Mail Code 4070
Stanford, CA  94305
mtang at stanford.edu

More information about the specmat mailing list