Hello !

I have some problem with my patterned gold electro-plating with Sodium Gold
Sulphate solution.  The pH of the solution is around 8 and I found out that
it etches photoresists (Shipley positive PR's such as 6812, 1512, etc)
slightly.  I evaporated Ti/Au (100/500 Angstrom) as a base metallization on
a semi-insulating GaAs and made a pattern with photoresist (~4~6 um thick) .
My problem here is that the patterns spaced closely (~ 10 microns) are
shorted (bridged) when the plated gold gets thicker that ~ 1.0 microns.  It
may sound very strange since the photoresist pattern is as thick as ~ 5~6
microns.  Although the solutions etches the PR slightly, the PR patterns are
still there).  However, it is happening here.  Did anyone have the same
problem and found a solution to this problem ?

For your reference, I used a 10gr/liter solution at 2~3mA/cm^2 which gives
me the plating speed of   ~0.1microns/min.

Best wishes,
Jong-In Song

Associate Professor
Dept. of Information and Communications
Kwangju Institute of Science and Technology (K-JIST)
572 Sangam-dong Kwangsan-ku
Kwangju, Korea 506-712
tel) +82-62-970-2208
fax) +82-62-970-2204