Multiple Voids

Pictured

Time Domain Imaging (TDI)™
Utilizes an echo (amplitude & polarity) arrival ‘time’ as a reference, such as standard A-Scan, B-Scan and C-Mode type images.

Multiple Voids

Bonded Wafer with Multiple Voids - Application Note 2581

Multiple Voids

Sample & Method

Two silicon wafers, bonded together. Echoes were gated at the depth of the bond between the two wafers.

Result

The numerous dark circular features are voids at the interface between the wafers. Circular voids are often caused by very tiny particles of SiO2 or other solid contaminants.