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Traceable Scanning Probe Nano-Characterization

Summary:

Research and development of rigorously SI traceable nano-characterization instrumentation, measurements, and procedures to enable a fundamental understanding of scanning probe interaction and characterization for nanostructures. A primary goal is to develop traceable reference measurements and artifacts to enable manufacturing of sub 10 nm structures and devices.

Technical Goals:

  • Develop and deliver measurements, standards, and infrastructural technologies that address critical needs for innovation and traceable metrology, process control and quality in manufacturing at the nanoscale.
  • Study fundamental tip surface interactions that affect the uncertainty of dimensional scanning probe measurements.
  • Provide SPM-based dimensional calibrations from micrometers to 0.1 nanometer.

Description:

The project provides the metrological underpinnings and reference measurements that support other instruments used in semiconductor manufacturing (internal and external customers). The activities which span from fundamental understanding of tip SPM image formation to instrument development, to standards development, are motivated by the need to provide SI traceable dimensional measurements for nanoscale features, supported by rigorous uncertainty specifications to users. The project currently has the only dimensional metrology AFM at NIST with direct traceability to the SI meter, and is in line with NIST and PML's priorities in disseminating traceable measurements for nanoscale features.

The best measurement uncertainty for a height sample using the T-AFM is 0.03 nm (K=2). Customers and collaborators who have used the NIST AFM calibration service include Bruker- Nano, NanoDevices, VLSI, Advanced Surface Microscopy, among others. SI traceable measurements for calibration sample vendors help underpin the national measurement system since these values are propagated to thousands of samples a year. These samples are then used on regular bases by the end users for nanoscale characterization and instrument evaluation.

NIST-traceable AFM

Figure 1. (a) Solid model of the NIST Traceable –Atomic Force Microscope (T-AFM) (b) T-AFM image of sub-nm steps on Si (100) atomically flat surface

Major Accomplishments:

2015

  • Validated basic model of CD-AFM lateral tip dither using very large tips (high lateral stiffness) to place lower bound on tip bending. – Dec. 2014
  • Completed upgrades of T-AFM mini-environment to current performance of +/- 3 mK - Jan. 2015

2014

  • Developed a CD-AFM tip characterization technique using SiSiO2 superlattices – Sept 2014
  • Characterized and qualified a next generation Traceable -AFM -Jan 2014
  • Co –wrote new sections and coordinated the roll out of the 2013 edition of the ITRS Metrology chapter. - March 2014

2013

  • Completed a VAMAS round robin on AFM tip characterization – October 2013
  • Developed uncertainty budgets for a critical dimension atomic force microscope
T-AFM laser path and stage. Motions in three axes are monitored by displacement interferometer.
Figure 2. T-AFM laser path and stage. Motions in three axes are monitored by displacement interferometer.

Lead Organizational Unit:

pml

Customers/Contributors/Collaborators:

Key industries and markets are semiconductor and other nano-technology manufacturing industries. These include integrated device manufacturers, instrument vendors, tip and standards suppliers. Key applications are linewidth metrology, photomask metrology, nanomechanics, reference metrology for high-throughput techniques, and defect metrology among others.

Internal and external customers include MML (NIST), SDMD standards projects, (NIST), SDMD optical and SEM metrology projects (NIST), VLSI Standards, SEMATECH, Photronics, FEI, and NanoTools.

Facilities/Tools Used:

  • Critical Dimension Atomic Force Microscope
  • Traceable Atomic Force Microscope

Figure 3. Photo showing inside the main chamber of the critical dimension AFM (CD-AFM). The key differentiating aspect of CD-AFM relative to conventional AFM is two-axis tip-surface interaction sensing and position control, as illustrated in the inset.
Figure 3. Photo showing inside the main chamber of the critical dimension AFM (CD-AFM). The key differentiating aspect of CD-AFM relative to conventional AFM is two-axis tip-surface interaction sensing and position control, as illustrated in the inset.

Staff:

Dr. Ronald G. Dixson, Project Co-Leader
Ndubuisi George Orji, Project Co-Leader
Joseph (Joe) Fu

Associate:

Xavier Bonnaud

Contact

Physical Measurement Laboratory (PML)
Semiconductor & Dimensional Metrology Division (683)

General Information:
301-975-5609 Telephone
301-869-0822 Facsimile

100 Bureau Drive, M/S 8212
Gaithersburg, Maryland 20899-8212