using spun-on nanotubes in process flow

Kurtin, Juanita N juanita.n.kurtin at
Mon Sep 18 09:15:58 PDT 2006

Hi Mary,
Thanks very much for the quick response, this does address all my
process needs, at least for this week!  I will talk to Uli and Ed or
Mahnaz about the various bits of equipment needed as soon as I get to
Stanford today.

I appreciate the help,


-----Original Message-----
From: Mary Tang [mailto:mtang at] 
Sent: Monday, September 18, 2006 8:57 AM
To: Kurtin, Juanita N
Cc: specmat at; Uli Thumser
Subject: Re: using spun-on nanotubes in process flow

Hi Juanita --

I take it that you need your answer today, so am taking the liberty of 
expediting your request.

1.  We don't generally allow powders in the lab, particularly nanotube 
powders.  If dropped or blown around, these things will spread 
everywhere and could create havoc with other people's experiments.  So, 
we ask that your initial mixing be done outside the lab.  We have a 
solvent bench in the wafersaw room that you could use for this.

2.  We do not normally stock dichlorethane or DMF -- you will have to 
bring your own.  The easiest way to do this is to order from Sigma and 
have it delivered here, to SNF, to the attention of you -- and a staff 
member who knows what you're doing.    If you order from Sigma today, it

should be here tomorrow.

3.  Uli is back from vacation and says it will take her 5 minutes to go 
over the sonicator at wbsolvent with you.  By the way, I don't know how 
big your vials are -- hopefully, they are pyrex (plastic is lousy at 
transmitting ultrasonic energy - as your a chemist, I'm probably 
insulting you by telling you that, but we always have to tell the 
EE's.)  We also may not have on hand all the nifty clamps and ringstands

you might want to mount/adjust positioning of your vial for optimal 
energy transfer -- so I would suggest you might want to bring your own 
or go over to biostores to pick some up.

4.  We have a spin coater outside the lab, in the wafersaw room solvent 
bench.  Ed or Mahnaz could show you how to use this.  Once you CNT's are

dry on your substrate, then you can bring the wafers back into the lab 
for subsequent processing (we assume they will be pretty darned well 
adhered at that point.)  So, you can use the headway2 or laurell for 
spincoating PMMA.  We recommend that you might want to use your own 
glassware for develop and lift-off, to minimize the possibility of 

Mahnaz/Ed -- does this sound reasonable?  Juanita -- does this address 
your process needs?


Kurtin, Juanita N wrote:

> Hi Mary, spec mat committee,
> I would like to use a layer of spun-on nanotubes (from either 
> dicholorethane or dimethylformamide) as the active layer in some 
> back-gated nanotube devices.  Here is my proposed process flow:
> Proposed process flow for devices from spun-on nanotubes:
> 1)      Bring prepared nanotube powder (capped) into lab
> 2)      Add 5 mL -10 mL of dicholorethane or dimethylformamide to the 
> poweder and re-cap
> 3)      Sonicate for 2 hrs in water bath (closed container)
> 4)      Spin-coat a small amount of the supernatant at various 
> dilutions onto prepared substrate (100 nm oxide on silicon w/etched 
> Hitachi alignment marks)
> 5)      Spin PMMA over nanotube layer
> 6)      Pattern source/drain electrodes with Hitachi and develop
> 7)      Deposit source/drain metal using Innotec
> 8)      Liftoff PMMA/metal
> Please let me know if this is acceptable, and which spin-coater I 
> should use,
> Thanks,
> Juanita Kurtin

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

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