ASTM E986-97

Standard Practice for Scanning Electron Microscope Beam Size Characterization

SCOPE
1.1 This practice provides a reproducible means by which the performance of a scanning electron microscope (SEM) may be characterized. This performance is a measure of the SEM-operator-material combination and is 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, -deflection waveform generation) for the suggested materials. The range of SEM magnification at which this practice is of utility is from 1000 to 200 000 X.  
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: 09-Oct-1997
• 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

• Replaced By: ASTM E986-04 - Standard Practice for Scanning Electron Microscope Beam Size Characterization
• Effective Date: 01-Jul-2004
• Referred By: ASTM F561-19 - Standard Practice for Retrieval and Analysis of Medical Devices, and Associated Tissues and Fluids
• Effective Date: 10-Oct-1997

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NOTICE: This standard has either been superseded and replaced by a new version or withdrawn.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: E 986 – 97
Standard Practice for
Scanning Electron Microscope Beam Size Characterization
This standard is issued under the fixed designation E 986; 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.
1. Scope 4. Significance and Use
1.1 This practice provides a reproducible means by which 4.1 The traditional resolution test of the SEM requires, as a
one aspect of the performance of a scanning electron micro- first step, a photomicrograph of a fine particulate sample taken
scope (SEM) may be characterized. The resolution of an SEM at a high magnification. The operator is required to measure a
depends on many factors, some of which are electron beam distance on the photomicrograph between two adjacent, but
voltage and current, lens aberrations, contrast in the specimen, separate edges. These edges are usually less than one millime-
and operator-instrument-material interaction. However, the tre apart. Their image quality is often less than optimum.
resolution for any set of conditions is limited by the size of the Operator judgment is dependent on the individual acuity of the
electron beam. This size can be quantified through the mea- person making the measurement and can vary significantly.
surement of an effective apparent edge sharpness for a number 4.2 Use of this practice results in SEM electron beam size
of materials, two of which are suggested. This practice requires characterization which is significantly more reproducible than
an SEM with the capability to perform line-scan traces, for the traditional resolution test using a fine particulate sample.
example, Y-deflection waveform generation, for the suggested
5. Suggested Materials
materials. The range of SEM magnification at which this
practice is of utility is from 1000 to 50 000 3 . Higher 5.1 SEM resolution performance as measured using the
procedure specified in this practice will depend on the material
magnifications may be attempted, but difficulty in making
precise measurements can be expected. used; hence, only comparisons using the same material have
meaning. There are a number of criteria for a suitable material
1.2 This standard does not purport to address all of the
safety concerns, if any, associated with its use. It is the to be used in this practice. Through an evaluation of these
criteria, two samples have been suggested. These samples are
responsibility of the user of this standard to establish appro-
priate safety and health practices and determine the applica- nonmagnetic; no surface preparation or coating is required;
thus, the samples have long-term structural stability. The
bility of regulatory limitations prior to use.
sample-electron beam interaction should produce a sharply
2. Referenced Documents
rising signal without inflections as the beam scans across the
2.1 ASTM Standards: edge. Two such samples are:
2 3
E 7 Terminology Relating to Metallography 5.1.1 Carbon fibers, NIST—SRM 2069B.
E 766 Practice for Calibrating the Magnification of a Scan- 5.1.2 Fracture edge of a thin silicon wafer, cleaved on a
ning Electron Microscope (111) plane.
3. Terminology 6. Procedure
3.1 Definitions: For definitions of terms used in this prac- 6.1 Inspect the specimen for cleanliness. If the specimen
tice, see Terminology E 7. appears contaminated, a new sample is recommended as any
3.2 Definitions of Terms Specific to This Standard: cleaning may adversely affect the quality of the specimen edge.
3.2.1 Y-deflection waveform—the trace on a CRT resulting 6.2 Ensure good electrical contact with the specimen by
from modulating the CRT with the output of the electron using a conductive cement to hold the specimen on a SEM
detector. Contrast in the electron signal is displayed as a stub, or by clamping the specimen on the stage of the SEM.
change in Y (vertical) rather than brightness on the screen. This Mount the specimen rigidly in the SEM to minimize any image
operating method is often called Y-modulation. degradation caused by vibration.
6.3 Verify magnification calibration for both X and Y direc-
tions. This can be accomplished by using Practice E 766.
This practice is under the jurisdiction of ASTM Committee E-4 on Metallog-
raphy and is the direct responsibility of Subcommittee E04.11 on X-Ray and
Electron Metallography.
Current edition approved Oct. 10, 1997. Published December 1997. Originally
published as E 986 – 84. Last previous edition E 986 – 92. Available from National National Institute of Standards and Technology,
Annual Book of ASTM Standards, Vol 03.01. Gaithersburg, MD 20899.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
E 986
−2 −4
6.4 Use a clean vacuum of 1.33 by 10 Pa (10 mm Hg) 6.12 Select the highest magnification that is sufficient to
or better to minimize specimen contamination resulting from allow critical focusing of the image and shows image-edge
electron beam and residual hydrocarbons interacting during transition from white to black contrast (for example, fuzziness)
examination. The presence of a contamination layer has a of at least 5-mm horizontal width in the photographed image.
deleterious effect on image-edge quality. 6.13 Rotate the specimen, not the scan, and shift the field of
6.5
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