True 3D Nanometrology: 3D-Probing with a Cantilever-Based Sensor

Area of Science:

• Nanotechnology and Metrology
• Advanced Instrumentation
• Surface Science

Background:

• Existing three-dimensional atomic force microscopes (3D-AFM) struggle to measure spatial dimensions independently.
• Accurate critical dimension (CD) measurements are crucial for semiconductor manufacturing and nanotechnology.

Purpose of the Study:

• To present a novel 3D-AFM head with true 3D-probing capabilities.
• To enable precise and independent measurement of spatial dimensions for advanced metrology applications.

Main Methods:

• Development of a 3D-Nanoprobe with a differential interferometer and optical lever system.
• Tactile 3D-probing for critical dimension (CD) measurements.
• Calibration of the 3D-Nanoprobe for spatial selectivity and stiffness.

Main Results:

• The developed 3D-AFM head demonstrates an average spatial selectivity ratio of 50:1 for x, y, and z directions.
• Quasi-isotropic stiffness achieved with ratios of 1.1:0.9:1.0 for x:y:z.
• Probing repeatability shows standard deviations of 0.18 nm (x), 0.31 nm (y), and 0.83 nm (z).
• Promising results obtained for repeatability, stability, pitch, and line edge/linewidth roughness (LER/LWR) on CD-line samples.

Conclusions:

• The novel 3D-AFM head offers true 3D-probing, overcoming limitations of current technologies.
• The system provides high spatial selectivity and excellent probing repeatability, suitable for critical dimension measurements.
• The developed technology shows significant potential for advancing nanoscale metrology and characterization.