ASTM E986-04

Standard Practice for Scanning Electron Microscope Beam Size Characterization

SIGNIFICANCE AND USE
The traditional resolution test of the SEM requires, as a first step, a photomicrograph of a fine particulate sample taken at a high magnification. The operator is required to measure a distance on the photomicrograph between two adjacent, but separate edges. These edges are usually less than one millimetre apart. Their image quality is often less than optimum limited by the S/N ratio of a beam with such a small diameter and low current. Operator judgment is dependent on the individual acuity of the person making the measurement and can vary significantly.
Use of this practice results in SEM electron beam size characterization which is significantly more reproducible than the traditional resolution test using a fine particulate sample.
SCOPE
1.1 This practice provides a reproducible means by which one aspect of the performance of a scanning electron microscope (SEM) may be characterized. The resolution of an SEM depends on many factors, some of which are electron beam voltage and current, lens aberrations, contrast in the specimen, and operator-instrument-material interaction. However, the resolution for any set of conditions is limited by the size of the electron beam. This size can be quantified through the measurement of an effective apparent edge sharpness for a number of materials, two of which are suggested. This practice requires an SEM with the capability to perform line-scan traces, for example, Y-deflection waveform generation, for the suggested materials. The range of SEM magnification at which this practice is of utility is from 1000 to 50 000 x. Higher magnifications may be attempted, but difficulty in making precise measurements can be expected.
1.2 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.

General Information

• Status: Historical
• Publication Date: 30-Jun-2004
• ICS: 31.120 - Electronic display devices
• ICS: 37.020 - Optical equipment
• Technical Committee: E04 - Metallography
• Drafting Committee: E04.11 - X-Ray and Electron Metallography

Relations

• Replaces: ASTM E986-97 - Standard Practice for Scanning Electron Microscope Beam Size Characterization
• Effective Date: 01-Jul-2004
• Replaced By: ASTM E986-04(2010) - Standard Practice for Scanning Electron Microscope Beam Size Characterization
• Effective Date: 01-Apr-2010
• Referred By: ASTM F561-19 - Standard Practice for Retrieval and Analysis of Medical Devices, and Associated Tissues and Fluids
• Effective Date: 01-Jul-2004

Standards Content (Sample)

NOTICE: This standard has either been superseded and replaced by a new version or withdrawn.
Contact ASTM International (www.astm.org) for the latest information.
Designation:E986–04
Standard Practice for
1
Scanning Electron Microscope Beam Size Characterization
This standard is issued under the fixed designation E986; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision.Anumber in parentheses indicates the year of last reapproval.A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
1. Scope detector. Contrast in the electron signal is displayed as a
changein Y(vertical)ratherthanbrightnessonthescreen.This
1.1 This practice provides a reproducible means by which
operating method is often called Y-modulation.
one aspect of the performance of a scanning electron micro-
scope (SEM) may be characterized. The resolution of an SEM
4. Significance and Use
depends on many factors, some of which are electron beam
4.1 The traditional resolution test of the SEM requires, as a
voltage and current, lens aberrations, contrast in the specimen,
first step, a photomicrograph of a fine particulate sample taken
and operator-instrument-material interaction. However, the
at a high magnification. The operator is required to measure a
resolution for any set of conditions is limited by the size of the
distance on the photomicrograph between two adjacent, but
electron beam. This size can be quantified through the mea-
separate edges. These edges are usually less than one millime-
surement of an effective apparent edge sharpness for a number
tre apart. Their image quality is often less than optimum
ofmaterials,twoofwhicharesuggested.Thispracticerequires
limited by the S/N ratio of a beam with such a small diameter
an SEM with the capability to perform line-scan traces, for
and low current. Operator judgment is dependent on the
example, Y-deflection waveform generation, for the suggested
individual acuity of the person making the measurement and
materials. The range of SEM magnification at which this
can vary significantly.
practice is of utility is from 1000 to 50000 3. Higher
4.2 Use of this practice results in SEM electron beam size
magnifications may be attempted, but difficulty in making
characterization which is significantly more reproducible than
precise measurements can be expected.
the traditional resolution test using a fine particulate sample.
1.2 This standard does not purport to address all of the
safety concerns, if any, associated with its use. It is the
5. Suggested Materials
responsibility of the user of this standard to establish appro-
5.1 SEM resolution performance as measured using the
priate safety and health practices and determine the applica-
procedurespecifiedinthispracticewilldependonthematerial
bility of regulatory limitations prior to use.
used; hence, only comparisons using the same material have
2. Referenced Documents meaning. There are a number of criteria for a suitable material
2 to be used in this practice. Through an evaluation of these
2.1 ASTM Standards:
criteria, two samples have been suggested. These samples are
E7 Terminology Relating to Metallography
nonmagnetic; no surface preparation or coating is required;
E766 Practice for Calibrating the Magnification of a Scan-
thus, the samples have long-term structural stability. The
ning Electron Microscope
sample-electron beam interaction should produce a sharply
3. Terminology rising signal without inflections as the beam scans across the
edge. Two such samples are:
3.1 Definitions: For definitions of terms used in this prac-
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5.1.1 Carbon fibers, NIST—SRM 2069B.
tice, see Terminology E7.
5.1.2 Fracture edge of a thin silicon wafer, cleaved on a
3.2 Definitions of Terms Specific to This Standard:
(111) plane.
3.2.1 Y-deflection waveform—the trace on a CRT resulting
from modulating the CRT with the output of the electron
6. Procedure
6.1 Inspect the specimen for cleanliness. If the specimen
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This practice is under the jurisdiction of ASTM Committee E04 on Metallog- appears contaminated, a new sample is recommended as any
raphy and is the direct responsibility of Subcommittee E04.11 on X-Ray and
cleaningmayadverselyaffectthequalityofthespecimenedge.
Electron Metallography.
6.2 Ensure good electrical contact with the specimen by
CurrenteditionapprovedJuly1,2004.PublishedJuly2004.Originallyapproved
using a conductive cement to hold the specimen on a SEM
in 1984. Last previous edition approved in 1997 as E986–97. DOI: 10.1520/
E0986-04.
2
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM
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the ASTM website. Gaithersburg, MD 20899.
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