Hi,

I've been using Ti/Al as contact metal for Si devices. I frequently use
RF probe for high speed testing on these devices. But it's known that Al
is easily oxidized when exposed to air so I found the contact became
worse (indicated from series resistance) after a few days of testing. I
sometimes used dilute HF/BOE to etch native Al oxide then continue the
testing. However, our lab is not allowed to use strong acid or HF so
it's very inconvenient to clean sample chips somewhere else and come
back for testing. Do you have other simple ways to do this? For example:
milder chemicals (which have very relaxed use/storage constraint) or
even without use of wet chemicals??

P.S. scratching through oxide for contact is not a good idea because the
RF probes are delicate and have flat feet (not like DC probes that I can
use as wildly as possible :-) )

Thank you!

Xiaochen