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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 metrology to enable manufacturing of sub 20 nm structures for the semiconductor/nanoelectronic industries. Efforts range from first-principles modeling of tip-sample interactions to measurement applications – divided into two main thrusts: (1) development & application of first-principles SPM metrology, (2) development & application of SPM metrology methods for crucial measurands (e.g., linewidth) in nanoelectronics. Specifically, the new traceable AFM (T-AFM) has incorporated displacement interferometry for first-principles traceability, and a CD-AFM with two axis tip-sample control is capable of imaging near-vertical nanostructures.

Description:

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 20 nm structures and devices for the semiconductor and nanotechnology industries. The effort spans the space from first-principles modeling of tip-sample interactions to industry-specific measurement applications. There are two major thrusts: (1) development & application of first-principles metrology SPM instruments, (2) development & application of SPM metrology methods for measurands such as linewidth that are crucial to the nanomanufacturing industry. The new traceable AFM (T-AFM) has incorporated displacement interferometry and replaces a prior generation instrument of this type. A current-generation CD-AFM, purchased under ARRA, is capable of imaging vertical sidewalls and structures of particular importance in semiconductor nanomanufacturing.

Activities include:

  • 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.

Concentrated efforts in:

  • Accurate artifacts and standards.
  • Fundamental understanding of SPM image formation/tip sample interaction.
  • Innovative new instrumentation and techniques.
  • Development of new metrology methods for important measurands.
  • The activities are motivated by the need to provide SI traceable dimensional measurements for nanoscale features, supported by rigorous uncertainty specifications to users.

This project is well aligned with the organizational priorities, since providing the traceability anchor for AFM dimensional nano-metrology is central to the SI length unit dissemination mission of NIST, PML, and SDMD. The emphasis of SDMD on the semiconductor and related nano-technology industries is also supported by the project focus on AFM metrology methods for semiconductor applications. Our ‘neutral arbiter’ position as the NMI of the U.S. also makes us a natural hub for certain interlaboratory comparisons and standards development activities.

Figure 2. This schematic illustrates the beam path of the interferometers in the new T-AFM. Incorporated interferometric displacement metrology for traceability to the SI meter is a key feature of this system.
Figure 2. This schematic illustrates the beam path of the interferometers in the new T-AFM. Incorporated interferometric displacement metrology for traceability to the SI meter is a key feature of this system.

Major Accomplishments:

  • Organized, edited, and authored paper for a special section of JM3 on AFM metrology.
  • Development of a procedure to measure semiconductor contours using CD-AFM.
  • Characterization of sub 10 nm line with less than 1 nm uncertainty.
  • Characterization and qualification of a third generation CD-AFM.
  • Completed tri-lateral interlaboratory comparison of 70 nm pitch using C-AFM.
Figure 1. Photo of interior of chamber of new traceable atomic force microscope (T-AFM). The sample chuck and optical navigation microscope are visible in the foreground. The granite block to which the AFM scanner is mounted is visible in the background.
Figure 1. Photo of interior of chamber of new traceable atomic force microscope (T-AFM).

Lead Organizational Unit:

pml

Customers/Contributors/Collaborators:

Key Customers:

Standards Manufacturers - VLSI Standards, ASM, etc.

  • The standards manufacturers are important customers because they provide broad dissemination of measurements traceable to the SI through NIST.

Semiconductor Device Manufacturers–IBM, Texas Instruments, Global Foundries etc.

  • Success in providing our customers with high quality measurements allow us to have an impact on a wide range of applications such as optics and photonics, data storage, as well as semiconductor device makers.

Instrument Manufacturers–Bruker, Asylum, etc.

  • Strategic collaboration through round robin comparisons and participation in standards development activities.

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
Boon Ping Ng (Former Guest Researcher)
Vladimir Ukraintsev (ARRA Postdoc)

Related Programs and Projects:

  • We collaborate closely with the “MEMS Measurement Science and Standards” project in group 683.03. The staff and capability base of that project provide the sample fabrication for the SCCDRM component of this work.

Associated Products:

  • Provided AFM metrology support to NIST SRM2059 and NIST Au nanoparticle RM8011, RM8012, and RM8013.
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