Mary Tang mtang at stanford.edu
Mon May 12 12:13:18 PDT 2008

Hi SpecMat'ers --

Before sending a reply to Johan, I thought I'd pass it by you.  Add your 
comments/suggestions, please:

Hi Johan --

APTES is OK to use in the lab in very specific areas.

1.  Keep liquid out of the litho area.  This could cause problems with 
surface quality in other people's wafers.
2.  Store the APTES in the flammables cabinet or flammables 
refrigerator.  (Does is require rfrigeration?  I don't think it can 
hurt, if tightly sealed.)  Make sure to have the barcode and yellow 
label.  Be aware that APTES should be kept as dry as possible, which 
includes minimizing the time the bottle is opened to air.  APTES will 
hydrolyze in the presence of trace moisture.  So, if you refrigerate, 
bring the bottle up to room temperature before opening, to minimize 
3.  Processing of your quartz should be done in wbsolvent.  If you are 
not already qualified, please talk with Uli about getting 
trained/qualified.  Work with her on your protocol.  I would suggest 
obtaining, using, and storing your own glassware.  Clean your labware 
first.  Trace chemicals can contaminate your wafer surfaces.
4.  We don't have a pH meter in the lab.  I'd suggest that actually pH 
paper would be better (more accurate and allow you to keep probes out of 
your solution), so you'd have to obtain paper with the appropriate 
range.  (By the way, it is a misconception that you actually obtain a 
monolayer -- it is actually quite difficult, I understand, to get a nice 
monolayer of APTES.)
5.  On step 3C, do not use the singe oven to bake the APTES coated 
wafer.  Please use one of the litho hot plates -- make sure to replace 
the foil on top before and after your APTES wafers are heated.

I believe the rest of the procedure is OK.  However, I do think that 
before committing your wafers to this process, it would be useful to do 
some quick experiments.  One experiment would be to see how well the 
i-line resist holds up to CHF3/O2 etching...  Typically, we have found 
that the i-line resist etches more quickly than the standard 3612.  I am 
not sure even the 3612 would stand up to 60 minutes of etching in the 
amtetcher.  It might help also to have an idea of the etch rate of X-cut 
quartz, so you'll know how long an etch the resist needs to withstand.

One last thing -- I would not do an HMDS singe/prime before coating your 
wafers with resist.  This could mess up your APTES coating.  Without 
HMDS, resist adhesion might be a problem.  (It may be that hand-develop 
might be required, if your resist dots wash off in the svgdev.)


Johan Andreasson wrote:
>    1. Contact information
>          1. Name                         Johan Andreasson
>          2. Coral login                  johana
>          3. Phone number             650-724-5536
>          4. E-mail address            johana at stanford.edu
>             <mailto:johana at stanford.edu>
>          5. Who I work for           Prof. Steven M. Block,
>             Biology/Applied physics
>    1. Chemical
>          1. Name                           3-AMINOPROPYLTRIETHOXYSILANE
>          2. Synonym                     C9-H23-N-O3-Si,
>             C9-H23-N-O3-Si, "1-propanamine, 3-(triethoxysilyl)",
>             "1-propanamine, 3-(triethoxysilyl)", "propylamine,
>             3-(triethoxysilyl)-", "propylamine, 3-(triethoxysilyl)-",
>             "silane, (3-aminopropyl)triethoxy-",
>             3-(triethoxysilyl)propylamine,
>             3-(triethoxysilyl)propylamine,
>             (3-aminopropyl)triethoxysilane, "silane,
>             gamma-aminopropyltriethoxy-", "aminopropyl triethoxy
>             silane", triethoxy(3-aminopropyl)silane,
>             gamma-aminopropyltriethoxysilane, "Union Carbide A-1100",
>             A1102, A1112, A0750, "Silicone A1100", APS, APSE, APTES,
>             "Dynasylan AMEO", GF93, KBE903, KBM903, KH550, "NUCA
>             1100", "Sila-Ace S330", "Silane AM69", "Prosil 220",
>             "Prosil 221", "VM651 Coupling Agent", APTS
>          3. Secondary chemical     Acetic acid and ethanol
>          4. Main hazards               Water reactives, corrosives
>          5. Storage group              B, Pyrophoric and Water
>             Reactive Materials
>    1. Vendor/manufacturer info
>          1. Address                       Sigma-Aldrich
>                                                 Customer Support
>                                                 PO Box 14508
>                                                 St. Louis, MO 63178
>                                                 UNITED STATES
>          2. Phone number             800-325-3010
>          3. Website URL              www.sigmaaldrich.com
>             <http://www.sigmaaldrich.com/> (company)
>             www.sigmaaldrich.com/catalog/search/ProductDetail/ALDRICH/440140-BULK
>             <http://www.sigmaaldrich.com/catalog/search/ProductDetail/ALDRICH/440140-BULK>
>             (product)
>    2. Reason for request
>          1. This is an essential material in the protocol for my
>             application, published in Nature methods last year (see
>             attachment Supplementary methods.pdf). There is no other
>             viable chemical that can replace APTES and the wafers,
>             later exposed with 0.5 µm features, need to be maintained
>             in a clean state. This has been attempted, by using our
>             own lab, but it proved very challenging.
>    3. Process flow
>          1. The APTES will be used for surface treatment of quartz
>             wafers, following initial cleaning in piranha solution and
>             adding of an antireflective coating on the back side of
>             the wafer.
>          2. 200 microliter of APTES will be pipetted into a beaker
>             containing a solution of 95% ethanol and 5% water,
>             adjusted to pH 5.0 using acetic acid. A quartz wafer will
>             be added and sonicated for 4 min. Then follows three wash
>             steps where the wafer is placed in 50 ml of ethanol and
>             sonicated briefly. This will lead to a monolayer of APTES
>             onto the clean side of the wafer.
>          3. The wafers are dried with a nitrogen gun and placed in a
>             115 degree oven for 20 min. (singe oven)
>          4. iLine resist added using svgcoat. The step includes a
>             pre-coat and post coat bake.
>          5. Exposure using the AMSL.
>          6. Post exposure bake and development using svgdev.
>          7. UV illumination and postbake at 110 degrees.
>          8. AMT etcher, CF3 and o2 etching.
>          9. Drytek2, polymer cleanup.
>         10. Removal of photoresist using WBsolvent. Sonication for 20
>             min in acetone.
>         11. Characterization in semhitachi
>    4. Amount and form
>          1. 100 ml liquid. It will be diluted to 1% immediately before
>             use.
>    5. Storage
>          1. I would like to store a small plastic bottle at SNF if
>             possible.
>          2. Potential reactivities:  strong oxidizing agents, acids,
>             moisture
>    6. Disposal
>          1. Local collection. APTES is water reactive so the storage
>             is probably best to be a separate waste container, where
>             the diluted APTES and ethanol from subsequent wash steps
>             are collected.

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

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