Auger Electron Spectroscopy |
Auger
electron spectroscopy (AES) determines the elemental
composition of conductive and semiconductive surfaces.
This information can then be utilized to solve problems
associated with surface appearance, cleanliness and
bondability.
Principles
of Operation
An electron beam bombarding a solid surface excites
electrons from core electronic energy levels of atoms.
A deep core electron is knocked out of an atom, a shallower
level electron drops into the deep core level hole,
and its energy loss is transferred to another shallower-lying
electron which can be ejected (the Auger electron).
The kinetic energy spectrum is used to identify the
atom of origin and its concentration. Small spot size
electron beams used to excite Auger electrons can be
used to produce
secondary electron images and, by tuning to a particular
Auger transition energy, produce elemental surface maps
of high lateral resolution.
Information
Obtained
° Surface composition analysis for metals, powders,
semiconductors, many
insulators, single crystal surfaces, fracture
surfaces
° Identification of particulates, localized dopants
or contaminants, visual defects
° Investigation of submicrometer dimension structures
° Grain boundary investigations, e.g. intergranular
corrosion
° Analysis of surface coatings and thin films
° When combined with ion sputtering, elemental depth
profiling of surface
and/or interfacial layers
Advantages
° Monolayer-sensitive surface analysis with high
spatial resolution
° Elemental mapping across surface
° Elemental depth profiling with uniform sensitivity
Sensitivity
and Resolution
° Surface Sensitivity: < 1 nm
° Lateral Resolution: < 50 nm
° Analytical Volume: 10-18 cm3
° Sensitive to all elements except hydrogen and
helium with detection limits
of 0.1-1% atomic or 0.1 monolayer
Instrumentation
° VG Microlab 310 Series D High Resolution Scanning
Auger Microprobe
equipped with a liquid metal ion gun, VG
SIMS MM12-12 SIMS with
positive and negative ion detection
and a VG 5250 Data System
° PHI 590 High Resolution Scanning Auger Electron
Microprobe equipped with
an ion sputter gun, PC based elemental
mapping and digital imaging
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