Characterization of high density through silicon vias with spectral reflectometry

Area of Science:

• Semiconductor Manufacturing
• Materials Science
• Metrology

Background:

• Accurate measurement and control are critical for production-ready through-silicon via (TSV) etching.
• Existing metrology tools require enhancement for inspecting high-density TSV (HDTSV) arrays.

Purpose of the Study:

• To adapt and improve a spectral reflectometer for HDTSV inspection.
• To develop a non-destructive metrology solution for critical TSV parameters.

Main Methods:

• Implemented a novel theoretical model and measurement algorithm for spectral reflectometry.
• Utilized Discrete Fourier Transform (DFT) analysis for one-shot depth and variation measurements.
• Applied scattering model fitting to extract via bottom surface roughness.

Main Results:

• Demonstrated measurement of TSV profile diameters as small as 5 μm.
• Achieved measurement of aspect ratios greater than 13:1.
• Obtained a measurement precision of 0.02 μm for via depth.

Conclusions:

• The enhanced spectral reflectometer provides a viable non-destructive solution for HDTSV metrology.
• The developed method enables precise measurement of critical TSV dimensions and surface characteristics.
• Results from actual 3D interconnect wafers validate the tool's effectiveness in production environments.