Comparison of line width calibration using critical dimension atomic force microscopes between PTB and NIST

Area of Science:

• Metrology and Measurement Science
• Materials Science and Engineering
• Nanotechnology

Background:

• International comparisons between National Metrology Institutes (NMIs) are crucial for validating measurement results and uncertainties.
• Accurate calibration of line width standards is essential for semiconductor manufacturing and nanotechnology applications.

Purpose of the Study:

• To compare the line width calibration of a crystalline silicon line width standard (IVPS100-PTB) between the Physikalisch-Technische Bundesanstalt (PTB) and the National Institute of Standards and Technology (NIST).
• To verify the consistency and accuracy of measurement results obtained through independently developed traceability pathways.

Main Methods:

• Critical Dimension Atomic Force Microscopy (CD-AFM) was employed as the primary measurement technique.
• Traceability pathways involved calibrating the atomic force microscope (AFM) scanner using step height and lateral standards.
• Effective tip width was traced to the silicon lattice parameter via High Resolution Transmission Electron Microscopy (HR-TEM).

Main Results:

• Good agreement was achieved between PTB and NIST for line feature critical dimensions (CDs) ranging from 50 nm to 130 nm.
• Observed deviations in CD results were between -1.5 nm and 0.3 nm.
• These deviations were well within the calculated measurement uncertainties, indicating high measurement agreement.

Conclusions:

• The comparison successfully validated the line width calibration capabilities of both PTB and NIST.
• The independently developed traceability pathways demonstrated robustness and reliability.
• The results support the confidence in metrological measurements for critical dimensions in advanced manufacturing.