Iodic Acid

Mary Tang mtang at
Tue Mar 17 09:52:48 PDT 2009

Hi Mike, Senyo --

Thanks for the reminder...  Just a couple of things.

1.  Powders (including crystals -- as well as free nanoparticles and 
nanotubes) aren't allowed in the cleanroom.  It's just too difficult to 
handle powders (dispensing, weighing, mixing) when there's laminar flow 
and exhaust blasting in different directions.  You can, however, mix 
solutions from powders outside the cleanroom, in the wafersaw room, and 
bring them in, either through the chemicals passthrough (get a staff 
member to help you with access) or using a single bottle carrier through 
the service area in the back.  Alternatively, if you can find a source 
of pre-mixed solution, you won't have to mix it up yourself. 

2.  Can you store the solution for an appreciable time or does it have 
to be mixed up just before use?  If you store the bottle of solution, it 
should be kept in the chemicals passthrough.  Make sure to get a yellow 
label.  I take it that a brown bottle should be sufficient for excluding 
light -- if you decide to also wrap it in foil or other covering, make 
sure to label the outside of the foil with all the critical info as well.

3.  Crystals should be stored outside the lab.  We have a corrosives 
room where this can be stored.  However, you'll need staff help to 
access the vault, so this will limit availability to working hours.

4.  How will you be disposing of the waste?  If you are etching III-V's, 
then etchant waste should be collected locally and appropriately 
tagged.  The unused acid itself, I believe, can disposed of by 
aspirating at the bench.

5.  Could you write up a procedure for this (like what you have below, 
but with the where's and how's)?



Mike Wiemer wrote:
> Hi Specmat,
> We would like to use Iodic Acid in SNF. This chemical is commonly used 
> as an echant for III-V materials like InP. MSDS attached.
> 1.)    Iodic Acid comes in dry crystal form
> 2.)    One mixes the crystals with water to form the acid (0.2 
> M/Liter) in a glass, non-transparent bottle (Iodic acid should be kept 
> from light)
> 3.)    We will mix the crystals & water to create the solution at the 
> GaAs bench
> 4.)    At the GaAs bench, we will combine: HIO3 (0.2M/L) :  HCl  : 
>  H2O  - 1:1:x where x goes from 1 to 100.
> 5.)    All work will be done at room temp
> 6.)    We will store the mixed solution in the personal chemical 
> pass-through area, along with the dry crystals
> What do you think?
> Thanks!
> -Mike

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

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