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Advanced 3D Imaging Approach to TSV/TGV Metrology and Inspection Using Only Optical Microscopy

Gugeong Sung

TL;DR

The paper addresses the need for fast, inline 3D metrology of silicon vias (TSVs) and through-glass vias (TGVs) by introducing a hybrid field microscopy approach that integrates photometric stereo with standard optical microscopy. By capturing images under multiple lighting directions, the method estimates surface normals and reconstructs depth maps to reveal interior and edge features without extensive sample preparation. The authors demonstrate 3D reconstructions on 2x2 blind TSV/TGV sets under several illumination conditions and validate diameter and depth estimates against references, showing useful accuracy with cost-effective hardware. This approach has the potential to enable non-destructive, in-line inspection in semiconductor manufacturing, though it faces challenges in light-path accuracy near heat-affected zones and at greater depths.

Abstract

This paper introduces an innovative approach to silicon and glass via inspection, which combines hybrid field microscopy with photometric stereo. Conventional optical microscopy techniques are generally limited to superficial inspections and struggle to effectively visualize the internal structures of silicon and glass vias. By utilizing various lighting conditions for 3D reconstruction, the proposed method surpasses these limitations. By integrating photometric stereo to the traditional optical microscopy, the proposed method not only enhances the capability to detect micro-scale defects but also provides a detailed visualization of depth and edge abnormality, which are typically not visible with conventional optical microscopy inspection. The experimental results demonstrated that the proposed method effectively captures intricate surface details and internal structures. Quantitative comparisons between the reconstructed models and actual measurements present the capability of the proposed method to significantly improve silicon and glass via inspection process. As a result, the proposed method achieves enhanced cost-effectiveness while maintaining high accuracy and repeatability, suggesting substantial advancements in silicon and glass via inspection techniques

Advanced 3D Imaging Approach to TSV/TGV Metrology and Inspection Using Only Optical Microscopy

TL;DR

The paper addresses the need for fast, inline 3D metrology of silicon vias (TSVs) and through-glass vias (TGVs) by introducing a hybrid field microscopy approach that integrates photometric stereo with standard optical microscopy. By capturing images under multiple lighting directions, the method estimates surface normals and reconstructs depth maps to reveal interior and edge features without extensive sample preparation. The authors demonstrate 3D reconstructions on 2x2 blind TSV/TGV sets under several illumination conditions and validate diameter and depth estimates against references, showing useful accuracy with cost-effective hardware. This approach has the potential to enable non-destructive, in-line inspection in semiconductor manufacturing, though it faces challenges in light-path accuracy near heat-affected zones and at greater depths.

Abstract

This paper introduces an innovative approach to silicon and glass via inspection, which combines hybrid field microscopy with photometric stereo. Conventional optical microscopy techniques are generally limited to superficial inspections and struggle to effectively visualize the internal structures of silicon and glass vias. By utilizing various lighting conditions for 3D reconstruction, the proposed method surpasses these limitations. By integrating photometric stereo to the traditional optical microscopy, the proposed method not only enhances the capability to detect micro-scale defects but also provides a detailed visualization of depth and edge abnormality, which are typically not visible with conventional optical microscopy inspection. The experimental results demonstrated that the proposed method effectively captures intricate surface details and internal structures. Quantitative comparisons between the reconstructed models and actual measurements present the capability of the proposed method to significantly improve silicon and glass via inspection process. As a result, the proposed method achieves enhanced cost-effectiveness while maintaining high accuracy and repeatability, suggesting substantial advancements in silicon and glass via inspection techniques
Paper Structure (15 sections, 6 figures)

This paper contains 15 sections, 6 figures.

Table of Contents

  1. Introduction
  2. MATERIALS AND METHODS
  3. Traditional Inspection Method
  4. Proposed Inspection Method
  5. Methodology
  6. Photometric stereo
  7. Hybrid Field Microscopy with Photometric Stereo
  8. Experiment
  9. Experimental setup
  10. Data Acquisition and Analysis
  11. RESULTS AND DISCUSSION
  12. CONCLUSION
  13. FUTURE WORK
  14. ACKNOWLEDGEMENTS
  15. REFERENCES

Figures (6)

  • Figure 1: A SCHEMATIC OF (A) THE HYBRID FIELD MICROSCOPY WITH (B) PHOTOMETRIC STEREO-BASED PROPOSED METHOD
  • Figure 2: OVERALL COMPOSITION OF EXPERIMENTAL EQUIPMENT FOR (A) TGV AND (B) TSV MEASUREMENTS
  • Figure 3: 2X2 ARRAY OF BLIND TSV/TGV SETS
  • Figure 4: 3D DEPTH MAP RECONSTRUCTION USING THE PROPOSED METHOD
  • Figure 5: COMPARISON OF (A) DIAMETERS AND (B) DEPTH BETWEEN THE REFERENCE AND ESTIMATED MODELS FOR BLIND TSV/TGV SETS
  • ...and 1 more figures