AFM

AFM MEASUREMENT AND IMAGING SERVICES

Also known as Scanning Probe Microscopy (SPM), Scanning Force Microscopy (SFM)

Atomic force microscopy (AFM), or scanning probe microscopy (SPM), measures the surface topography of materials at a very high resolution down the scale of a few nanometers laterally, and less than a nanometer in Z, under ambient conditions. While AFM complements other microscopy techniques, such as SEM and optical microscopy, AFM provides avenues of investigation not possible with other techniques.

AFM achieves this feat by using a very sharp-tipped micromachined silicon cantilever, raster-scanned over the sample surface. A laser photodiode beam reflected off the back of the cantilever, monitored by a photodetector connected to a piezoelectrically driven feedback loop that controls the scanning of the AFM tip across the surface. By maintaining a constant deflection of the cantilever, the voltages applied to the piezo are used to derive a topographic map of the surface. Below, you’ll find more information about our AFM services and common measurements for the different AFM modes we support.
AFM

INDUSTRIES & APPLICATIONS WHERE AFM IS COMMON:

Thin films development, semiconductors, MEMS, optical components, coatings, piezoelectric materials, and magnetic materials are common uses of AFM services.

Read White Paper

Atomic Force Microscopy for Advanced Optical Components

MEASUREMENTS GROUPED BY AFM MODE

AFM Modes Sample Typical data Typical Turnaround Time
Contact AFM All types Surface topography, 3D mapping, roughness < 48h
Tapping Mode AFM All types Surface topography, 3D mapping, roughness, phase imaging < 48h
Electrostatic (EFM) Composite Metal, Semiconductor films Local charge distribution < 48h
Magnetic (MFM) Magnetic films Magnetic domain structure, magnetization hysteresis, magnetic coercive field < 48h
Piezoresponse (PFM) Piezo materials, MEMS Piezo domain structure, polarization vector and switching, ferroelectric coercive field < 48h
Peak Force AFM Thin-film Roughness, Surface topography < 48h
Peak Force Quantitative Nanomechanical (QNM) Polymer Coating Mechanical properties (adhesion, modulus and dissipation), Phase imaging, Polymer domains < 48h
Kelvin Probe (AM-KPFM) Thin films, Semiconductors Surface potential, work function < 48h

MEASUREMENTS MADE VIA AFM:

  • Topography and surface quality: Complete 3D model of a sample’s surface with sub-Å vertical resolution and lateral resolution on the nanometer to sub-nanometer scale.
    • Full 3D/2D topography
    • Roughness (Ra, Rq)
    • Step height
    • Profile slices
    • Cross-sections
    • Particle counts
    • Defect Analysis
  • Mechanical characterization and phase mapping: adhesion, modulus and dissipation
  • Magnetic domains, magnetization hysteresis, and magnetic coercive field.
  • Surface potential and work function.
  • Piezoelectric domains, polarization vector and switching, and ferroelectric coercive field.
  • Electrostatic gradients and capacitance variations.

Uses & Limitations of AFM:

  • What our AFM services are great for:
    • Quantified topography/ roughness of very smooth samples
    • Best z resolution
    • Surface imaging of insulating samples with no extra sample prep
    • High definition functional properties mapping (mechanical, electric, magnetic, piezo)
    • Imaging topography of samples in liquid
    • Defect Analysis
  • Limitations:
    • Requires expertise for reliable results, even on seemingly easy samples
    • No compositional mapping available

Related Techniques:

Depending on the exact problem you are trying to solve and data desired, potential related techniques are:

Our technical team is happy to clarify on what technique will provide you with the best data.

EXAMPLE OUTPUTS OF AFM

Atomic Steps of Epitaxial Silicon: Tapping Mode AFM, 3D render

AFM Output

Tapping Mode Topography (left) and KPFM (right) on ITO showing variations in surface potential.

KPFM can measure the work function of thin film surfaces as well as resolve minute differences in the surface potential using lift mode to remove topographic contributions.

Quantitative Nano-mechanical Microscopy of Carbon Fiber Encapsulated in Epoxy

  • Carbon fibers are apparently softer than the surrounding epoxy matrix.
  • Log DMT Modulus shows the fibers brighter (more resilient) than the more firm surroundings.
  • The deformation channel shows the tip compressing the fiber ends on the order of 2 nm.

Electrostatic Force Microscopy of Titanium Carbide- Alumina Surface

  • Topography image on the left shows the higher TiC grains suspended in the Al2O3 matrix.
  • The EFM or phase image shows differences in the electrical attraction of the tip to the TiC grains and the alumina.

INSTRUMENTS USED FOR AFM

Bruker Nano Dimension (Icon and FastScan heads)