BCL3 or CL2 used together will allow you to etch aluminum. The BCL3 is used
to remove AL2O3 which forms on the surface of the aluminum then switching to
Cl2 process will allow removal of native aluminum. The problem you will
encounter will be the problem when you reach the GaAs substrate. Chlorine
will etch it even faster than it does the Aluminum. Unless you have a good
endpoint system to determine when you are finished with the Aluminum I am
afraid you will get mixed results. Contact Gordon Whitlock at Trion
Technology. His phone is 480-968-8818 x 11. Trion is a leader in the failure
analysis deprocessing business and they might be able to give more
information on conditions. Bob Henderson