[labnetwork] Cadmium Telluride sputtering target exchange problems
Pramod Karulkar
pkarulkar9 at gmail.com
Sun Jun 21 16:41:54 EDT 2009
Explosive oxidation of very pure thin films in a vacuum chamber is
known. Popping sounds can be heard if a chamber used for depositing
titanium or aluminum is suddenly exposed to room air. Flash of light
can also be seen if the chamber is full of dust or peeling matter. Both
can be dangerous. You have to set up protocols for slow venting,
waiting for a long time ( hour or hours) to allow for slow passivation
of unoxidized materials, and then opening the chamber. Vent and pump
cycles may help too. Check with your vendor.
Slow venting may reduce peeling and release of particles. You have to
allow the whole system to reach room temperature (or slightly above RT)
before venting it. However, some peeling of material will occur and the
chimney and chamber walls/parts will have to be cleaned thoroughly using
a dedicated vacuum cleaner. Again protocols for this will have to be
set up. You may follow processes/precautions used to clean similar
equipment such as CVD chambers or ion implant source chambers. Color of
the flakes depends on the composition and surface finish. "Black" may
not mean anything. It may be an off stoichiometric deposition with
residual gas contamination that may vary with position in the chamber.
Smells are hard to track down unless you sample the gas and analyze.
Complex species are formed if you are doing anything reactive in the
chamber. Smells can arise from back streaming of some vapors from a
pumping station. Check with the vendor. Repeated cycles of venting and
rough pump down without opening the door will help to reduce the
concentration of smelly components. (Plasma etch chambers tend to have
unusual odors. Well exhausted bench, hood, enclosure etc has to be used
to clean such chambers. A mask is needed to.)
Vendor websites used to have info on such topics. If you did not
download and save it, most of it is gone because of the newer style of
websites.
http://www.asm.com/index.php?option=com_content&task=view&id=51&Itemid=67
Hope this helps.
Pramod C Karulkar
Fairbanks Alaska
907 457 4123
443 622 4425
Keith Bradshaw wrote:
>
> We are getting a strong smell from the chamber and instant oxidation
> and flaking of product deposited on the chimney of our Sputtering
> system when changing the Cad-Tel target.
>
>
>
> What is done to avoid this?
>
>
>
> Is this smell harmful?
>
>
>
> The flakes are very dark and seem to form when we open the system up
> to atmosphere. It is load locked so normally it doesn't see air.
>
>
>
> Keith Bradshaw
>
> 972-883-2099
>
> RL 10
>
> University of Texas at Dallas Clean Room
>
> NSERL building
>
>
>
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