Ultra-Sensitive Visualization and Identification of Defects in Microelectronics Packaging

Defects in microelectronics packaging can have deleterious effects to device reliability; increasingly smaller feature sizes push demands of sophisticated identification tools into higher spatial resolution than previously required. Non-destructive, sub-micron spatial resolution infrared Optical PhotoThermal InfraRed (O-PTIR) chemically resolves ~1-2 μm gap-filling defects previously not possible with conventional vibration spectroscopy tools (Raman and FT-IR). This novel infrared-based technique employs a pump-probe infrared-visible dual laser illumination scheme that provides sub-micron spatial resolution and high sensitivity while avoiding sample damage caused by laser illumination. Since the O-PTIR technique is not affected by autofluorescence (AF) of materials upon illumination of visible laser, fluorescence images (FL) can be readily used to rapidly locate the region of interest where the defects are present, even in unfavorable conditions where dark-colored underfill shows no contrasts in the white light optical images. For the first time, the co-located FL and O-PTIR in a single measurement tool realizes rapid direct chemical analyses.