We used to keep the sulfuric hot and add just a little peroxide at the time
you add the wafers. Please check with you safety officer. We stripped the
resist from many boat loads of wafers before dumping the sulfuric.  Also, we
found ammonium persulfate could be used instead of the small amount of
peroxide.  Again, check with the safety department.  It may be illegal in
your area.

Roger Brennan
Applications Director
Solecon Labs
Reno, NV 89521-5926

-----Original Message-----
From: [email protected]
[mailto:[email protected]]On Behalf Of DEBASHIS MAJI
Sent: Tuesday, January 26, 2010 1:24 PM
To: General MEMS discussion
Subject: [mems-talk] Piranha Reaction


Dear all,

I shall be highly thankful if anyone can kindly tell the effect of change in
the ratio of H2O2 and H2SO4 (normally 1:1) in Piranha solution. I know that
this reaction takes place in the following order : H2O2 + H2SO4 = HSO4(-) +
H3O(+) + O. It is this nascent oxygen that is used in cleaning or surface
treatment, etc. I would like to know the effect of increase in sulphuric
acid conc. say from 1:1 to 3:1 in the piranha solution. Would it result in
more vigorous reaction with more nascent O? if so how do the equations
go...?

Kindly help me out regarding this. Thanks in advance.

Debashis Maji