Yttria Stabilized Zirconia Request

Mary Tang mtang at
Thu Jun 17 08:09:13 PDT 2004

Hi everyone --

Any updates or thoughts on this?


Tim Schultz wrote:

> 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
> from:
> 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
> found:
> 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:
> svgcoat
> svgdev
> karlsuss
> nikon
> convection ovens - 90C,110C,150C
> wbmetal
> wbnonmetal
> 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
> room.):
> 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.
>   ------------------------------------------------------------------------
>                                               Name: RTA for YSZ Gate Dielectrics.pdf
>    RTA for YSZ Gate Dielectrics.pdf           Type: Portable Document Format (application/pdf)
>                                           Encoding: base64
>                                    Download Status: Not downloaded with message
>                                 Name: YSZ Report MAS.doc
>    YSZ Report MAS.doc           Type: WINWORD File (application/msword)
>                             Encoding: base64
>                      Download Status: Not downloaded with message
>                                                     Name: Zirconia and Hafnia as Gate Oxides.pdf
>    Zirconia and Hafnia as Gate Oxides.pdf           Type: Portable Document Format (application/pdf)
>                                                 Encoding: base64
>                                          Download Status: Not downloaded with message
>                                         Name: LSI YSZ Process 6-5-04.doc
>    LSI YSZ Process 6-5-04.doc           Type: WINWORD File (application/msword)
>                                     Encoding: base64
>                              Download Status: Not downloaded with message
>                           Name: YSZ MSDS.doc
>    YSZ MSDS.doc           Type: WINWORD File (application/msword)
>                       Encoding: base64
>                Download Status: Not downloaded with message

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

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