Hi Dear Colleages;

I am writing this e-mail in TURKIYE.We are interesting with FPA fabrication.
But in one step,we have run into a cause. This problem is removing under
bump metallization. But at the same  time we would like to guard our
interconnect bump metals for read out circuit.

We have used gold and titanium to cover under bump metallazition. When we
used gold for UBM we obtained very good bump metalization that we are using
indium. But we didn't remove gold.(we didn't litf off this metal..)When we
used titanium for UBM we accepted bump metallization. But Not very good. (i
think problem is resistivity of titanium ) As you know titanium remove with
using HF. But HF also damage our indium bump.

We have used these tecniques in the bottom side for removing Gold. But All
tecniques damaged indium bump.

1.      Freon in RIE
2.      I2 + KI + H20
3.      King Water

Do you know different tecniques for removing gold.(But simultaneously it
does not damage  to indium.

Best Regards.


Tolga YELBOGA
Project Engineer
Nanotechnology Researh Center
Bilkent University
Bilkent, Ankara 06800 TURKEY
Voice: 90-312-290-1020
www.nanotr.bilkent.edu.tr