1. Key Defect Detection

Delamination

SAM detects unbonded areas at wafer bonding interfaces caused by abnormal process parameters (insufficient pressure, temperature fluctuation) or surface contamination. Such defects appear as low-reflection dark regions or phase-reversal signals in ultrasonic images.

Voids / Bubbles

It identifies voids formed by trapped gas or uneven resin flow within the bonding layer. Voids show as irregular black spots in C-scan, while B-scan can locate their vertical depth distribution.

Cracks and Inclusions

High-frequency ultrasonic waves with resolution down to 1 μm capture microcracks and particle inclusions induced by mechanical stress or foreign contaminants during bonding.

2. Technical Advantages

Non-destructive Testing

Penetrates wafers and packaging materials (epoxy resin, ceramic substrates) to visualize internal interfaces without sample destruction.

High Resolution & 3D Imaging

High-frequency probes above 30 MHz enable detection of micron-scale defects, including tiny delaminations induced by nanoparticles.

Combined with 3D tomographic scanning (X/Y/Z axis), it reconstructs defect morphology to evaluate propagation risks.

Process Compatibility

Suitable for advanced semiconductor packaging such as 2.5D/3D packaging, IGBT modules and SiC devices, supporting inline quality control and process optimization.

3. Application Scenarios

Bonding Process Validation

Evaluate bonding quality after wafer surface activation (plasma treatment, CMP polishing), avoiding partial non-bonding caused by excessive surface roughness.

Assess uniformity of thermocompression and cold compression bonding to optimize temperature–pressure parameter combinations.

Packaging Reliability Analysis

Detect underfill delamination in Flip Chip, BGA solder ball voids and other hidden defects to ensure long-term service stability.

Monitor interfacial defects in heterogeneous bonding (such as silicon–glass bonding) to prevent failure caused by thermal expansion mismatch.

4. Technical Extensions and Challenges

Edge Defect Inspection: Combined with edge trimming processes such as wet etching and CMP, SAM locates microcracks and delaminations induced by stress concentration at wafer edges.

High-throughput Requirement: Current technology needs to balance resolution and scanning speed. Fast parallel scanning algorithms are required for mass inspection of 12-inch wafers.

Summary

By accurately identifying interfacial defects, SAM has become a core quality control tool for advanced semiconductor packaging. It will continue evolving toward higher frequency and intelligent detection to match future process upgrades.