ASTM E673-98E1
(Terminology)Standard Terminology Relating to Surface Analysis
Standard Terminology Relating to Surface Analysis
SCOPE
1.1 This terminology is related to the various disciplines involved in surface analysis.
1.2 The definitions listed apply to (a) Auger electron spectroscopy (AES), (b) X-ray photoelectron spectroscopy (XPS), (c) ion-scattering spectroscopy (ISS), (d) secondary ion mass spectrometry (SIMS), and (e) energetic ion analysis (EIA).
General Information
Relations
Standards Content (Sample)
NOTICE: This standard has either been superseded and replaced by a new version or discontinued.
Contact ASTM International (www.astm.org) for the latest information.
e1
Designation: E 673 – 98
Standard Terminology Relating to
Surface Analysis
This standard is issued under the fixed designation E 673; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (e) indicates an editorial change since the last revision or reapproval.
e NOTE—Old term “electron attenuation length” was deleted editorially in November 2000.
1. Scope generated. Also see information depth.
analyzer transmission— see spectrometer transmission.
1.1 This terminology is related to the various disciplines
angle:
involved in surface analysis.
collection—SIMS, the angle between the normal to the
1.2 The definitions listed apply to ( a) Auger electron
original specimen surface and the axis of the secondary ion
spectroscopy (AES), (b) X-ray photoelectron spectroscopy
collection optics.
(XPS), (c) ion-scattering spectroscopy (ISS), (d) secondary ion
of detector—EIA, SIMS, the angle between the incident
mass spectrometry (SIMS), and (e) energetic ion analysis
beam direction and the direction pointing from the beam spot
(EIA).
to the center of the detector.
2. Abbreviations of emission—AES, XPS, the angle of emission or ejection of
electrons from a solid measured relative to the normal to the
2.1 Abbreviations commonly used in surface analysis are as
surface.
follows:
of incidence— the angle between the incident beam and the
AES Auger electron spectroscopy
normal to the surface.
BS backscattering spectroscopy
CHA concentric hemispherical analyzer
of scattering—EIA, the angle between the incident beam
CMA cylindrical mirror analyzer
direction and the direction in which a particle is traveling
EIA energetic ion analysis
eV electron-volts after it is scattered. If the particle is incident on the detector,
ESCA electron spectroscopy for chemical analysis
this angle will be the same as angle of detector.
FABMS fast atom bombardment mass spectrometry
solid, of detector—EIA, the solid angle intercepted by the
FWHM full width at half maximum peak height
ISS ion scattering spectroscopy detector, with the radius originating at the beam spot.
pp peak-to-peak
takeoff—AES, XPS the angle at which particles leave a
RBS Rutherford backscattering spectroscopy
specimen measured relative to the plane of the specimen
RFA retarding field analyzer
SAM scanning Auger microprobe surface. (see angle of emission).
SIMS secondary ion mass spectrometry
angle lapping—a method of specimen preparation in which a
SNMS sputtered neutral mass spectrometry
specimen is mechanically polished at an angle so that
XPS X-ray photoelectron spectroscopy
changes in composition as a function of position, usually
3. Terminology Definitions
depth, can be more easily determined.
angle resolved AES—the recording of Auger electron spectra
adventitious carbon referencing— XPS, a method of deter-
as a function of angle emission.
mining the charging potential of a particular specimen by
angular distribution of secondary ions—see secondary ions.
comparing the experimentally determined binding energy of
attenuation coefficient—for a parallel beam of specified
the C 1s peak maximum from contaminating hydrocarbon or
particles or radiation, the quantity μ in the expression μDx
hydrocarbon groups on the specimen to a standard binding
for the fraction removed in passing through a thin layer Dx
energy value.
of a substance in the limit as D x approaches zero, where Dx
analysis:
is measured in the direction of the beam.
area—a two-dimensional region of a specimen surface,
Auger:
usually measured in the plane of the specimen surface, from
analysis volume—see volume under analysis.
which a specified percentage of the signal is detected.
chemical effects—AES, see chemical.
volume—a three dimensional region of a specimen from
chemical shift—AES, see chemical.
which a specified percentage of the measured signal is
current—the electron current due to the emission of Auger
electrons.
This terminology is under the jurisdiction of ASTM Committee E42 on Surface
electron—an electron emitted as the result of an Auger
Analysis and is the direct responsibility of Subcommittee E42.02 on Terminology.
process.
Current edition approved Nov. 10, 1998. Published March 1999. Originally
published as E 673 – 79a. Last previous edition E 673 – 97. electron yield— the probability that an atom with a vacancy
Copyright © ASTM, 100 Barr Harbor Drive, West Conshohocken, PA 19428-2959, United States.
E 673
in a particular inner shell will relax by an Auger process. (for example, L L M) it is referred to as a Coster-Kronig
1 2
line scan—a plot of Auger signal strength as a function of transition. If both electrons are from the same principal shell
displacement along a designated line on the specimen as the initial vacancy (for example, M M M ) it is called a
1 2 3
surface. Normally, the abscissa is the line along which the super Coster-Kronig transition.
signal is measured and the ordinate is directly proportional to transition rate— the probability per unit time for two bound
signal strength. electrons to undergo energy state transitions such that one
line shape—the energy distribution in an Auger spectrum for will fill an initial core hole vacancy and the other will go to
a particular Auger transition. a final state in the positive energy continuum.
map—two dimensional image of the specimen surface Auger electron spectroscopy—the measurement of Auger
showing the location of emission of Auger electrons from a signal strength as a function of electron energy.
particular element. A map is normally produced by rastering average emission function decay length— the negative
the incident electron beam over the specimen surface and reciprocal slope of the logarithm of a specified exponential
simultaneously recording the Auger signal strength for a approximation to the emission depth distribution function
particular transition as a function of position. over a specified range of depths, as determined by a
matrix effects—see matrix effects, Auger. straightline fit to the emission depth distribution function
parameter—XPS, the kinetic energy of the sharpest Auger plotted on a logarithmic scale versus depth on a linear scale.
peak in the spectrum minus the kinetic energy of the most background:
intense photoelectron peak from the same element; the inelastic—ISS, the response of the energy filtering and
energy of the ionizing photons must be specified. detection system to probe ions that have undergone inelastic
peak energy for dN(E)/dE, N(E)—the designation of the scattering events at the specimen surface.
energy of the Auger electron distribution. In dN/dE spectra, instrumental—ISS, the response of the energy filtering and
peak energies should be measured at the most negative detection system to events other than those induced by
excursions of the Auger features. In N(E) spectra, peak bombardment of the specimen surface by a beam of probe
energies are measured at peak maxima. (Peak energies in ions.
dN/dE spectra are not the same as those in N(E) spectra.) secondary ion—ISS, the response of the energy filtering and
process—the relaxation, by electron emission, of an atom detection system to secondary ions produced by bombard-
with a vacancy in an inner electron shell. ment of the target material with probe ions.
signal strengths—AES, XPS, in dN/dE spectra, signal signal— for a specific measurement, any signal present at a
strengths are measured as the peak-to-peak heights of the particular position due to processes or sources other than
Auger features. In N(E) spectra, signal strengths are mea- those of primary interest.
sured as the heights of the Auger peaks above background. backscattered electrons— AES, electrons originating in the
In I(E), signal strengths are measured as the areas under the incident beam which are emitted after interaction with the
electron energy distribution, N(E). target. By convention, electrons with energies greater than
spectrum, dN(E)/dE, N(E), I(E)—AES, the display of Auger 50 eV are considered as backscattered electrons.
signal strength as a function of electron energy. Auger backscattering:
spectra from solids may be measured as the first derivative of energy— EIA, energy of a particle from the analyzing beam
the electron energy distribution and may be designated by after it has undergone a backscattering collision and escaped
dN/dE. The Auger electron energy distribution may be the specimen.
designated as N(E). With certain type analyzers (for ex- factor— AES, the fractional increase in the Auger current
ample, the CMA) the displays are dEN(E)/dE and EN(E). due to backscattered electrons.
The area under Auger peaks may be designated as I(E) with spectrum—EIA, a plot of backscattering yield (ordinate)
background subtraction method, and integration limits speci- versus backscattering energy (abscissa).
fied. yield— EIA, the number of particles detected (counts) per
transition—transitions involved in electron emission by an unit backscattering energy per incident ion.
Auger process are designated by indicating the electron ball cratering—a method of specimen preparation in which a
shells. The first letter designates the shell containing the specimen is polished by a sphere in order to expose
initial vacancy and the last two letters designate the shells compositional changes below the original surface of a
containing electron vacancies created by Auger emission specimen with the intent that the depth of these layers can be
(for example, KLL, and LMN). When a bonding electron is related to the position on the surface created by the ball.
involved the letter V is used (for example, LMV and KVV). beam:
When a particular subshell involved is known this can also analyzing—same as incident.
be indicated (for example, KL L ). Coupling terms may also current—the total current incident on the specimen by the
1 2
be added where known (L M M ; D). More complicated primary particle source.
3 4,5 4,5
Auger processes (such as, multiple initial ionizations and current density— the current incident on the specimen per
additional electronic excitations) can be designated by sepa- unit area.
rating the initial and final states by a dash (for example, diameter—in surface analysis, the full width of the incident
LL-VV and K-VVV). When an Auger process involves an beam at half maximum intensity measured in a plane normal
electron from the same principal shell as the initial vacancy to the beam direction. This plane must be specified and is
E 673
often taken at the intersection of the beam center with the the analog-to-digital converter used for spectrum production.
specimen. channeling—motion of energetic particles along certain axial
divergence, convergence—angles spanned by the directions
or planar directions of a crystalline solid as the particles
of all particles of the incident beam. penetrate the specimen. The potentials of the individual
energy—the energy of the particles incident on the specimen
atoms of the solid combine to reduce scattering with those
surface, expressed in electron volts (eV). atoms.
energy, primary— the kinetic energy of the primary beam,
channeling—SIMS, the process by which particles preferen-
usually expressed in kiloelectronvolts (keV).
tially penetrate crystalline specimens in certain crystallo-
incident—the energetic particles incident on the specimen.
graphic directions because of the relatively open arrange-
particle—atomic or molecular species contained in the
ment of atoms presented to the impinging particle beam.
incident beam, regardless of state of ionization.
characteristic electron loss phenomena—AES, the inelastic
primary—a directed flux of particles (ions or neutrals)
scattering of electrons in solids that produces a discrete
incident on the specimen.
energy loss determined by the characteristics of the material.
profile, primary ion—the spatial distribution of the primary
The most probable form is due to excitation of valence
ion current in a plane perpendicular to the primary ion beam
electrons. For some solids (for example, nontransition met-
axis.
als), inelastic scattering is dominated by plasmon excitations
size—the full width at half-maximum of the beam at a given
(a collective excitation of valence electrons). For other
point in space that must be defined.
solids, the inelastic scattering may be due to a combination
spot—the area on the specimen surface illuminated by the
of plasmon excitation and single valence electron excita-
incident beam.
tions. Inelastic scattering can also occur through the excita-
binary elastic scattering event— ISS, the collision between
tion of core level electrons when this is energetically
an incident probe ion and a single surface atom in which the
possible.
total kinetic energy and momentum are conserved.
characteristic X-rays—photons emitted by ionized atoms and
binary elastic scattering peak— ISS, an increase in the
having a particular distribution in energy and intensity
spectrometer detection system response above the back-
characteristic of the atomic number and chemical environ-
ground level which can be attributed to binary elastic
ment of the atom; in XPS, the term is ordinarily used in
scattering of the probe ion from a surface atom of a
reference to the X-ray source of the spectrometer.
particular mass.
charge:
binding energy—the work that must be expended in removing
charge modification—any method used to alter the amount
an electron from a given electronic level to a reference level,
or the distribution of charge on a specimen surface.
such as the vacuum level or the Fermi level.
charge neutralization—ISS, SIMS, a technique in which a
blocking geometry—EIA, experimental situation wherein the
surface under ion bombardment is maintained at a known
atom rows or planes of a single crystal target are aligned
potential by compensating for the accumulated charge.
parallel to a vector from the specimen to the detector.
charge referencing—any method used to adjust the energy
Bragg’s rule—an empirical rule formulated by W. H. Bragg
scale calibration of a spectrometer to accommodate the
and R. Kleeman that states that the stopping cross section of
effects of steady-state charging of a specimen surface.
a compound specimen is equal to the sum of the products of
charging potential—in surface analysis, the electrical poten-
the elemental stopping cross sections for each constituent
tial of the surface of an insulating specimen caused by
and its atomic fraction, that is,
irradiation. If the specimen is heterogeneous, there may be
e~A B ! 5 xe 1 ye (1)
x y A B different charging potentials on
...
Questions, Comments and Discussion
Ask us and Technical Secretary will try to provide an answer. You can facilitate discussion about the standard in here.