Electromagnetic analysis for optical coherence tomography based through silicon vias metrology

Area of Science:

• Metrology
• Optical Engineering
• Microelectronics

Background:

• Through-silicon vias (TSVs) are critical for 3D integration in microelectronics.
• Accurate dimensional metrology of TSVs is essential for reliable device performance.
• Existing models for TSV analysis may have limitations.

Purpose of the Study:

• To analyze time-domain optical coherence tomography (OCT) for TSV dimensional metrology.
• To estimate deviations from simpler models in TSV analysis.
• To develop an accurate and efficient method for determining TSV heights.

Main Methods:

• Utilized time-domain optical coherence tomography (OCT) on 1D trenches and circular holes.
• Incorporated dispersion from reference interferograms of a planar substrate.
• Applied a rigorous modal approach and a Fabry-Perot model approximation.
• Developed an iterative procedure minimizing a merit function.

Main Results:

• Quantified differences between modal analysis and ray tracing techniques for TSVs.
• Demonstrated the effectiveness of a Fabry-Perot model for computation acceleration.
• Validated an iterative procedure for reliable and accurate TSV height determination.

Conclusions:

• The developed OCT-based iterative procedure reliably measures TSV dimensions.
• This method offers improvements over simpler models for TSV metrology.
• Accurate TSV metrology is crucial for advancing 3D microelectronic integration.