A Lot of SpecMat Items
edmyers at stanford.edu
Fri Jan 19 10:38:19 PST 2007
Here is the latest SpecMat Logsheet. The official meeting was last
Tuesday (1/16), but I was running behind. Please let me know if
there are any objections to the open items by Monday evening, 1/22.
Item 220: The GST film will first be etched using an approved etch
tool. I would like to use either the MRC or a gold-contaminated etch
system plumbed with Cl chemistry.
Comments: I know we have been processing GST in the facility. I
thought this request would be a natural extension until I started
looking some MSDS sheets for the chlorides. I am very concerned
about the hazards we may be subjecting to our users and
maintenance. If we do allow this, it should have a high
barrier. This would include limited, pre-approved equipment usage
followed by a maintenance clean.
Item 221: 1) Why is no matter (metal?) allowed in the KOH
decontamination process? Is it because KOH usually attacks
metal? What if the metals are capped by oxide, will this be allowed
to go through the decontamination procedure? 2) Tystar used to be a
semi-clean poly deposition tool but I heard it's no longer in the fab.
Recommendation (response): I will explain the KOH concerns. We have
approved clean metals in tylan poly if the user does a coat following
deposition. Do we want to expand this to semi-clean wafers? I
believe we need to do this, under Maurice's guidance and pre-clean
requirements. This will include wafers which come from a number
processing steps including dry etching.
Recommendation: I will push back with health concerns and see if the
user has a different way of patterning.
Item 237: 15 um of undoped poly-Si in Tylan Poly tube
Comments: It is not noted, these wafers will come from an
STSetcher. Kris indicated 1.5um per pass was the limit on new boats
(narrow slots) or 2um per pass for the wide slot boats. This is for
test wafers and the process will ultimately move to an epi system.
Recommendations: Approve 1 run with breaks at every 1.5um, unless we
can find the wide sloted boats where we can use a 2um
deposition. Cleans prior to deposition should be 1)photoresist
removal, 2) Standard Pre-LPCVD cleans in Wbsilicide, 3) Standard
Item 329: Unity 4411 for the sacrificial layer. Start with clean
silicon wafer, 2. Spin coated at headway2, 3. Solvent removal at
100C hotplate 5mins , 4. cured at blueM oven at 200C for 2hrs
(<100ppm O2), 5. Sputtering metal for the mask - Metalica (need to
know the temperature the wafer can experience), 6. Pattern the metal
mask (svgcoat/evaling/svgdev/wbgen), 7. Dry etch at MRC or
drytek1, 8. Remove metal mask at wbgen, 9. Sputtering Cr/Au in
Metalica for the metal suspended structure, 10. Pattern the Cr/Au
(svgcoat/evaling/svgdev/wbgen), 11.polymer decomposition in BlueM
upto 405C (<1ppm O2)
Recommendations: Approved processing sequence, but need to work with
requester in finding correct furnaces for the anneals.
Item 218: Use Ammonium dichromate as a photosensitizer in litho process.
Recommendation: Approved. Either needs a pre-made solutions of this,
or order, store, and make up solutions outside the lab. PVA is an
approved chemical which needs to should be collected locally and
labelled as hazardous waste.
Item 224: PVP is cured at 175 or 200 C and is reported in the
literature as OK for high vacuum evaportion of electrodes. I can't
believe it would be worse than photoresist as used for lift-off. I
will add a de-hydration bake (110 C, 20 minutes) just before Innotec.
Recommendation: Approved, as long as spin coating is done outside the fab.
Item 226: Bismuth/Antimony Telluride. Initially I will be doing SEM
work. Later I will be depositing metals, thereby encapsulating the
Bi/Sb-Te, and patterning the metals. I do not know the specifics of
the equipment that would be used but they would be the 'contaminated'
class of tools.
Recommendation: Approve for metal deposition in gold contaminated
equipment. Need to see if they will be patterning the top metal by
RIE and make sure they are in the correct etcher. Need to keep an
eye on the user to make sure his not only using SNL.
Item 227: 1. application of polycarbonate plastic film in Innotech.
2. Bring in outside wafer after CMP. The surface at this stage
surface contains SiO2 and carbon. 3. SiO2 etch in drytek 4 of a wafer
having both SiO2 and carbon on the surface. 4. PECVD SiO2 dep on a
wafer that has carbon nanotube exposed. My process flow is the
following: 1. Silicon Nitride deposition on Si wafer (clean) 2. Litho
to pattern the nitride 3. Ni (10nm) and Fe (3nm) deposition through
an polycarbonate membrane and SS shadow mask in Innotech. (cont) 4.
PECVD SiO2 depoosition (cont) 5. CMP (outside lab) 6. Drytek 4 etch
of SiO2 (cont) 7. PECVD SiO2 dep (cont) 8. Cr dep (cont)
Item 228: I would like to get approval for using HBr -liquid form -
for etching InP wafers.
Recommendation: Approved with the stipulation to have a minimal
amount of concentrated HBr solution stored at SNF and a suggestion
that it be kept in a larger, labeled, enclosed, secondary container
(like one of those single chemical bottle carriers.) and keep as
little of this stuff on-site as possible.
Item 229: Can the XeF2 be ran a both a gold contaminated and semiclean tool?
Recommendation: Yes, We will manufacture and dedicate the sample
platen for each material classification.
Item 230: Protek from Brewer Scientific
Recommendation: Approved previously
Item 231: I would like to bring a PZT sol-gel solution into
SNF....Solvent system is 2-methoxyethanol.
Comments: The process flow looks compatible with the gold
contaminated equipment set, however the iconic "glycol ether" that
we've been trying to phase out. We can approve this experiment with
restrictions on handling and make a request to change the solvent
system for future use.
Item 232: two chemicals for surface passivation of GaAs wafers: 1-
ammonium sulfide. Formula: (NH4)2Sx, 2- Thioacetamide. Formula:CH3CSNH2
Recommendation: Approve with limitations. We would need a detailed
procedure for what she plans to do (concentrations, mixtures,
etc.) Both are crystals, so it would be easier to bring in solutions
directly into the lab than solids that she'd have to mix up. Both
are actually flammable and react with acids to form toxic H2S gas, so
any work with these chemicals would need to be done in a solvent
bench, NOT wbgaas.
Item 233: HSQ XR-1542 negative ebeam resist.
Recommendation: Previously approved for Headway only.
Item 234: process step where the lot moves from STS deep etch to
LPTEOS dep. Comments: The wafers can go through multi-levels of
chemical cleans following STS etch.
Recommendations: Approve with the following clean sequence:
1)photoresist removal, 2) Standard Pre-LPCVD cleans in Wbsilicide, 3)
Follow wafer deposition with 0.5um furnace coating.
Item 235: Clean classification for the Fusion tool.
Recommendation: Use the Litho, All classification.
Item 236: Adding N2 to the AMT Etcher for a O2 for a patterning etch
Recommendation: Approve temporary installation by the maintenance group.
Item 238: DUV112-6 from Brewer Science and we plan to use this
together with the resists you have in-house (PMMA, UVN-30) for DUV lithography.
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