XR-1541 (HSQ) ebeam resist

Alexander Driskill-Smith alexander.driskill-smith at grandisinc.com
Fri Dec 15 17:37:10 PST 2006

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
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
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
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
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