Bottom-Up Generated Height Gauges for Silicon-Based Nanometrology.

Area of Science:

• Materials Science
• Metrology
• Nanoscience and Nanotechnology

Background:

• Integrated circuit design advancements necessitate new nanoscale metrology standards.
• Current methods lack convenient physical gauges for precise nanoscale surface measurements.
• Silicon lattice parameter is a secondary realization of the SI meter.

Purpose of the Study:

• To propose and validate self-organized silicon surface morphologies as gauges for nanoscale height measurements (0.3-100 nm).
• To enhance the accuracy of atomic force microscopy (AFM) and optical interferometry for metrology-grade measurements.
• To establish silicon-based height gauges using bottom-up approaches.

Main Methods:

• Utilized 2 nm sharp AFM probes to measure terrace roughness and monatomic step heights on Si(111) surfaces.
• Employed a step-free silicon terrace as a reference mirror in an optical interferometer.
• Used a pit-patterned silicon terrace with counted monatomic steps for optical measurements.

Main Results:

• Achieved 10 pm accuracy for step height measurements using AFM, with terrace roughness minimally affecting results.
• Reduced systematic error in optical interferometry height measurements to ~0.12 nm, enabling visualization of 136-pm-high steps.
• Optically measured Si(111) interplanar spacing agreed with precise metrological data, validating the method.

Conclusions:

• Self-organized silicon surface morphologies serve as effective gauges for nanoscale height measurements.
• The proposed methods significantly advance optical interferometry and AFM for metrology.
• This work paves the way for silicon-based height gauges and improved nanoscale metrology.