Non-Destructive Visualization of bond pad cratering defects using acoustic microscopy in the GHz-band
Non-Destructive Visualization of bond pad cratering defects using acoustic microscopy in the GHz-band
Monday, October 29, 2018: 11:35 AM
120A (Phoenix Convention Center)
Summary:
GHz scanning acoustic microscopy (GHz-SAM) was successfully applied to evaluate the integrity of the back end of line (BEOL) stack below bond pads. Two different sample types with different IC processes and artificially induced bonding defects were prepared and investigated. Due to the low penetration depth in the GHz regime, a specific sample preparation was conducted in order to provide access to the region of interest. Cratering related cracks in the bond pads can be clearly imaged whose morphology corresponds to the results yielded by a chemical cratering test. Moreover, delamination defects at the interface between ball and pad metallization have been identified. Thus, for the first time a semi-destructive technique - which actually is non-destructive concerning the region of interest - is available which enables the analysis of micron-sized defects in BEOL layer structures related to wire bonding or test needle imprints.
GHz scanning acoustic microscopy (GHz-SAM) was successfully applied to evaluate the integrity of the back end of line (BEOL) stack below bond pads. Two different sample types with different IC processes and artificially induced bonding defects were prepared and investigated. Due to the low penetration depth in the GHz regime, a specific sample preparation was conducted in order to provide access to the region of interest. Cratering related cracks in the bond pads can be clearly imaged whose morphology corresponds to the results yielded by a chemical cratering test. Moreover, delamination defects at the interface between ball and pad metallization have been identified. Thus, for the first time a semi-destructive technique - which actually is non-destructive concerning the region of interest - is available which enables the analysis of micron-sized defects in BEOL layer structures related to wire bonding or test needle imprints.