[labnetwork] Diborane stability

[Bob Hamilton]

Savitha,

The mix of diborane and Ar will not be as stable as B2H6 in H2 and 
higher order boranes will form faster. I regret I cannot share 
experience with such a mix. Voltaix, a manufacturer of hydride gases may 
be able to offer guidance:
http://www.voltaix.com/

Having said this you may want to look at other possible issues. Mass 
flow controller have a a heated bypass sensor and this capillary bypass 
is subject to blockage if diborane is left within the mfc at the 
termination of a process. For this reason, when we used diborane we used 
an in and out isolation valve. We'd close the supply and then pump out 
the mfc so there was virtually no B2H6 in the mfc at idle.

At the UC Berkeley NanoLab we are not currently using diborane as a 
dopant having obviated it for 1% BCl3/bal He in our LPCVD processes. We 
may be using it again in our epi process. The carrier gas in that case 
will be H2.

Regards,
Bob Hamilton

On 9/23/2013 5:21 AM, Savitha P wrote:
> Hi!
>
> We have diborane (2% in Ar carrier gas) connected to our APCVD furnace as
> the source for boron doping. For the past one month we have not achieved
> resistivity changes with any of our standard recipes. Our cylinder was
> installed in 2011 and is kept at ~22-24 deg C.
>
>   I have been reading some of the previous posts about the formation of
> B4H10 particles which deposit out. Has anyone noticed this kind of
> phenomena leading to only flushing of the carrier Argon gas. We tried
> rolling of our cylinder for ~1hr (on the advice of our cylinder supplier)
> but had no better results.
>
> Thanks and regards,
>
> Savitha
>

-- 
Robert Hamilton
University of California at Berkeley
Marvell NanoLab
Equipment Eng. Mgr.
Room 520 Sutardja Dai Hall
Berkeley, CA 94720-1754
bob at eecs.berkeley.edu
Phone: 510-809-8600
Mobile: 510-325-7557
e-mail preferred