Zhu,

HCl is not your best choice to etch Ti.  Try H2O2.  It will etch very fast
and even faster when heated.

Brent

"X.P. Zhu" wrote:
> A layer of Ti was deposited on substrate by e-beam.
> But I can not make pattern on it by HCl. Is there an
> oxidation layer on Ti film which protects it? If so,
> how long does it take to form an oxidation layer after
> the film exposed to the air? And how to remove this
> layer by wet or dry etching? Thanks a lot!