Scanning Electron Microscopy

Scanning Electron Microscopy (SEM)

Scanning Electron Microscopy (SEM) encompasses a broad range of techniques which use an electron beam to generate images of a material surface. SEM is used both in independent material characterization and in preparation of samples for analysis via other techniques.

Covalent provides a wide array of capabilities in SEM applications. For a surface-level summary of our SEM services, please refer to the table below, and feel free to contact us with any questions.

SEM Technique Typical Applications
SEM Imaging ServicesSEM HR-SEM (High-resolution-SEM) CD-SEM (Critical Dimension-SEM) E-SEM (Environmental-SEM) Imaging of sample surfaces with resolution of ~10nm (SEM) to <1nm (HR-SEM) Measurements of surface and topographical features Bulk processing of particulate samplesAscertain particle size, feature dimensions, surface characteristics, structuresIncludes top-down and cross-sectional variants Defect characterization: measurements at specific sites of defect size, layer thickness, surface roughness, etc. Characterization of materials in near-environmental conditions (e.g. at non-ambient temperatures, and/or UHV-atmospheric pressure conditions).
FIB-SEM (Focused Ion Beam-SEM) All the imaging capabilities of the HR/SEM techniques maintained System includes additional focused-ion-beam column which enables:Cross sectioning; andBulk material evacuation / milling; andSample manipulation at site-specific locations Used to prepare electron-transparent cross sections for TEM analysis.
pFIB-SEM (Plasma Focused Ion Beam-SEM) Delivers the full faculties of the FIB-SEM with absolutely unrivaled efficiency and with customizable beam chemistries never previously available Used to prepare samples which could not previously have been treated with the Ga ion beam in standard FIB-SEM; multiple ion species enable new uses for the technique in bio/life sciences and other industries
SEM-EDS (SEM-Electron Dispersive Spectroscopy) All the imaging capabilities of the HR/SEM techniques maintained System includes additional x-ray detector(s) which enable:Chemical composition measurements; andCompositional mapping of elemental distribution in materials

Scanning Electron Microscopy (SEM & FE-SEM)

Scanning electron microscopy (SEM) is an essential tool for virtually all materials sciences projects, including advanced materials and thin films. SEM measurement techniques are used for high magnification and high-resolution observation of sample surfaces. Scanning electron microscopy uses an electron beam to explore the surface of a sample. The interaction of these electrons with the specimen causes various signals to be emitted, such as secondary electrons, backscattered electrons, Auger electrons, cathodoluminescence, and X-rays. Capturing and analyzing these signals yields a wealth of information about the sample’s morphology and texture, chemical composition, and crystalline structure.

Industries:

All materials development, thin films development, semiconductors, optical components, and coatings are common uses of scanning electron microscopy.

Measurements:

  • Surface imaging
  • Particle sizes and features dimensions (including film thickness, features height) with calibrated instruments
  • Top-Down SEM: used to image the top surface of the sample to look for defects
  • Cross-sectional SEM (X-SEM): used to look at the sample structure
  • CD-SEM: used to produce dimensional information such as defect size, layer thickness, surface roughness
  • Defect Review SEM: used to navigate to a particular location on a sample normally supplied by another inspection tool and image the defect or help in particle identification

Uses & Limitations:

  • What Covalent Metrology’s scanning electron microscopy services are great for:
    • Combining surface topography and elemental mapping
    • Rapid-high resolution imaging technique
  • Limitations:
    • Sample preparation can be required and destructive (limits on sample size, non-conductive samples need to be coated)
    • Functional properties mapping limited
    • Surface topography quantification impossible in 3 dimensions
    • Samples must be vacuum compatible
    • Electrostatically focused SEM required for magnetic samples since magnetic sample’s resolution degraded when magnetically focused systems (the most common type of SEM) are used

Contact us for more information regarding our SEM measurement and imaging services.

Example Outputs

Cross section of a defect (high resolution FIB-SEM): solvent contamination has created a bubble during processing of this sample. A targeted FIB cut reveals the void, then imaged with high resolution FE-SEM.

Focused Ion Beam SEM (FIB-SEM)

A FIB/SEM tool combines a FIB (focused ion beam) column along with the capabilities of an SEM. The FIB column is typically used for ion-milling of materials (i.e. removal), to enable site-specific investigation of sub-surface features by SEM (i.e. X-SEM). The FIB column can also be used for imaging samples, when electron beam contrast mechanisms fail to produce adequate signal for imaging.

A typical use for FIB-SEM is site-specific TEM sample preparation. Material around a region of interest is milled/removed, and then the sample (lamella, or region of interest) is removed using a nano-manipulated probe and placed on a TEM grid. The lamella is further thinned by the FIB to a final thickness between 20-70nm thick. The FIB also allows users to site specifically deposit Pt or C bands (in situ deposition), which help hold structures together during manipulation. In situ deposition is also particularly important for device editing, generation of ohmic contacts, protecting bean sensitive areas, and other sample-modification applications.

Applications:

TechniqueDescription
Top-Down SEMUses the electron beam to image the top surface of the sample to look for defects
Cross-sectional SEM (X-SEM)Uses the electron beam to look at the sample structure, layer thickness, layer roughness, voids….
Top-down FIBUses the ion beam to image the top surface of the sample to look for defects and structure
Cross-section FIBUses the ion beam to look at the sample structure, layer thickness, layer roughness, voids….

Example Outputs

Cross section of display (FIB-SEM): this cross section reveals the structure of pixels in fine detail.