Yttria Stabilized Zirconia Request

Tim Schultz tschultz at
Tue Jun 8 08:28:13 PDT 2004

Special Materials Committee,

I am re-requesting approval to process wafers deposited with a thin film of
yttria stabilized zirconia. This specific request
is for use of lithography equipment and resist strip equipment (for rework)
as noted in #12 below.

There has been confusion as to what tools our material is approved for. At
one time this material was approved for the metal chamber of the P5000, and
Lilliputian Systems was performing lithography on the material long before I
joined the company in February. Recently we were told we could not use the
wbmetal or wbnonmetal benches for resist strip, although we had thought we
were approved for these benches.

We have found YSZ to be extremely stable and inert. HF is the only dry or
wet etch chemistry we have found so far that has any significant effect.
Attached are 2 papers which describe the use of YSZ for gate dielectrics and
discuss the materials thermal stability. Also attached are technical notes
from the manufacturer.

In response to #17 below, attached is a materials analysis report of an
as-deposited wafer. The only contaminant found was Hafnium at less than 1
at.%, which is typical of YSZ from any supplier.

We have had one on one discussions with members of the special materials
committee who told us they would give us a reply within the week. This did
not occur. We would greatly appreciate a timely response to this formal
written request.

1) Requestor name:

Tim Schultz (for Lilliputian Systems)

2) Phone number:

707 344-1756

3) email address:

tschultz at

4) Requestor’s PI (Advisor) or Company:

Lilliputian Systems
46560 Fremont Blvd, Suite 419
Fremont, CA 94538

5) The name of the new Chemical (give all names commonly used):

YSZ, Yttria Stabilized Zirconia

6) N/A

7) Name of vendor/manufacturer that you are planning to obtain this material

The material is applied as a thin film by Barr Associates, the material is
manufactured by Fuel Cell Materials, a subsidiary of NexTech Materials.

8) URL for vendor’s website where info on the proposed chemical can be

9) Vendor’s address and phone number:

Barr Associates, Inc., 2 Lyberty Way, Westford, MA 01886, 978-692-7513
NexTech Materials & Fuel Cell Materials, 404 Enterprise Drive, Lewis Center,
OH 43035-9423, 614-842-6606

10) What is your reason for wanting to bring this material into the lab:

Fuel Cell Process Development

11) Make a strong case why you can not use an already approved
chemical/material for this purpose:

This is the material that meets our product requirements.

12) List all the lab equipment and wet benches that you propose to use with
this chemical:

convection ovens - 90C,110C,150C

13) Proposed quantity of the chemical that you want to bring into lab (give
both raw and mixed quantities):

0.5-20 micron thin film on Si/SiO2/SiN 4" substrate (all ox and nit
depositions at SNF), 6-15 wafers per lot

14) State the form that the proposed chemical is in. (Is it solid, powder or
liquid? Note: as a general rule, powders are not permitted in the clean

Solid thin film on substrate.

15) N/A

16) From manufacturer, vendor or the Stanford safety site, obtain a legible
Material Safety Data Sheet (MSDS) for all the proposed chemicals. Send these
to the person listed below.

See attachment.

17) If the chemical/material is to be used in any the "clean" equipment,
purity specifications will be needed. This is most important for
chemicals/material that are not normally used for VLSI device fabrication.
To be allowed into a "clean" tool, the material should MOS grade or better.

See attachment.

18) Read the MSDSs as well as the Stanford Chemical Storage Groups and the
Stanford Chemical Safety Data Base sections on this website to determine the
Storage Group Identifier and Main Hazard Class of your chemical/material:

Storage Group: G
Main Hazard Class: Non-hazardous
Additional Hazards: dust can cause lung and skin irritation.

19) N/A

20) In your discussions with vendors, try to determine the best way to
dispose of your spent chemicals and by-products. The lab has acid/base, HF
and solvent drains. The acid/base drains go to a neutralization system
before going the city waste water system. The city of Palo Alto has tight
limits on the amount of heavy metals that be disposed of through the waste
water system. If your chemical contains any metals, there is a good chance
that you will have to collect all your waste and dispose of it in labeled
containers which are picked up the Health and Safety Department. The HF
drains go to a central tank which is pumped out by a HF disposal service at
considerable expense on a regular basis. The solvent drains in the solvent
benches are collected under the benches and disposed of by Heath and Safety
as needed.

Disposal: Standard landfill methods consistent with applicable Federal,
State and local law.

21) Put together a detailed process flow description on how you proposed to
use this chemical. This should include: Any chemical mixing, all lab
equipment and wet benched to be used, all containers to be used, where
chemical is to be stored and how chemical and by-products are to be deposed
of. This should be in a Word file attached to your e-mail request. In
reviewing your procedure, we will be most interested in how the safety and
contamination issues are to be dealt with.

See Attachment.
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