1. Damage under UCSB bias bonds
After plucking bias wire bonds in order to re-bond with higher loop heights, damage is seen on all modules on second sensor
At minimum, “dots” seen at the edge of the guard ring and n+ metal directly under wire
At maximum, lines of metal deposited in the area between the guard ring and n+ metal directly under wire
Beginning of damage seen after a 20 minute ARCS test
Guard Ring
Guard Ring
n+ metal
Guard Ring
n+ metal

2. Damage under UCSB channel bonds
Under all channel bonds, the passitivation is discolored at guard ring, bias ring, DC pad, and bond pad
Channel bond location
Channel bond
location
Guard Ring
n+ metal

3. Damage to Bias Wire Bonds
After seeing Al deposited onto the sensor’s surface, we looked at the underside of the bias return wire bonds for damage
We found that all 4 bias return wire bonds studied are pocked in same region. This region lies above the n+ metal on the outside of the module
We assume that corona is causing ionization of Al which then follows electric field to sensor surface