Standard Test Method for Scanning Electron Microscope (SEM) Analysis of Metallic Surface Condition for Gas Distribution System Components

SCOPE
1.1 This test method covers the testing of interior surfaces of components such as tubing, fittings, and valves for surface morphology.
1.2 This test method applies to all surfaces of tubing, connectors, regulators, valves, and any metal component, regardless of size.
1.3 Limitations:  
1.3.1 This methodology assumes a SEM operator skill level typically achieved over a 12-month period.
1.3.2 This test method shall be limited to the assessment of pits, stringer, tears, grooves, scratches, inclusions, stepped grain boundaries, and other surface anomalies. However, stains and particles that may be produced during specimen preparation should be excluded in the assessment of anomalies.
1.4 The values stated in SI units are to be regarded as the standard. The inch-pound units given in parentheses are for information only.
1.5 This standard does not purport to address all of the safety problems, 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. Specific hazard statements are given in Section 6.

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09-Jun-1999
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ASTM F1372-93(1999) - Standard Test Method for Scanning Electron Microscope (SEM) Analysis of Metallic Surface Condition for Gas Distribution System Components
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NOTICE: This standard has either been superseded and replaced by a new version or withdrawn.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: F 1372 – 93 (Reapproved 1999)
Standard Test Method for
Scanning Electron Microscope (SEM) Analysis of Metallic
Surface Condition for Gas Distribution System
Components
This standard is issued under the fixed designation F 1372; 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.
INTRODUCTION
Semiconductor clean rooms are serviced by high-purity gas distribution systems. This test method
presents a procedure that may be applied for the evaluation of one or more components considered for
use in such systems.
1. Scope SRM 20690 SEM Performance Standard
1.1 This test method covers the testing of interior surfaces
3. Terminology
of components such as tubing, fittings, and valves for surface
3.1 Definitions:
morphology.
3.1.1 defect—a pit, scratch, groove, inclusion, stringer,
1.2 This test method applies to all surfaces of tubing,
stepped grain boundary, crack, or other surface feature that is
connectors, regulators, valves, and any metal component,
either characteristic of the material or a result of its processing
regardless of size.
that is not a result of the sample preparation.
1.3 Limitations:
3.1.2 grid size—the grid size (length of the x- and y-axis
1.3.1 This methodology assumes a SEM operator skill level
grid dimension) will be 1.814 µm multiplied by the magnifi-
typically achieved over a 12-month period.
cation of the photomicrograph. For example, for a standard 4
1.3.2 This test method shall be limited to the assessment of
by 5-in. photographic image at 3500 3 magnification, the grid
pits, stringer, tears, grooves, scratches, inclusions, stepped
would be 0.635 by 0.635 cm (0.25 by 0.25 in.).
grain boundaries, and other surface anomalies. However, stains
3.1.3 groove—a two-dimensional defect on the surface that
and particles that may be produced during specimen prepara-
has depth and width.
tion should be excluded in the assessment of anomalies.
3.1.3.1 Discussion—For this kind of defect, the depth is
1.4 The values stated in SI units are to be regarded as the
greater than the width, or, conversely, the width is greater than
standard. The inch-pound units given in parentheses are for
the depth.
information only.
3.1.4 inclusion—particlesofaforeignmaterialinametallic
1.5 This standard does not purport to address all of the
matrix (see Fig. 1).
safety concerns, if any, associated with its use. It is the
3.1.4.1 Discussion—These particles are usually compounds
responsibility of the user of this standard to establish appro-
(such as oxides, nitrides, carbo-nitrides, sulfides, or silicates),
priate safety and health practices and determine the applica-
but may be of any substance (and is essentially insoluble in the
bility of regulatory limitations prior to use. Specific hazard
metal matrix).
statements are given in Section 6.
3.1.5 number of anomalies—the total number of defects per
2. Referenced Documents photomicrograph (see 10.1.1).
3.1.6 particles that loosely adhere—particles in which over
2.1 NIST Standards:
2 ⁄4 of the bulk of the particle is above the plane of the surface.
SRM 484 F SEM Magnification Standard
3.1.6.1 Discussion—These particles generally appear very
bright, and little detail of the surface of the particle is seen
This test method is under the jurisdiction of ASTM Committee F-1 on
when the contrast and brightness are adjusted to image the
Electronics and is the direct responsibility of Subcommittee F01.10 on Processing
sample surface.
Environments.
3.1.7 pit—a small, sharp, roughly circular cavity in the
Current edition published Apr. 15, 1993. Approved June 1993. Originally
metal surface (see Fig. 2).
published as F 1372 – 92. Last previous edition F 1372 – 92.
Available from National Institute of Standards and Technology, Gaithersburg,
MD 20899.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
F 1372 – 93 (1999)
FIG. 1 Example of Inclusion (3600 3 magnification)
FIG. 3 Example of Stringer (3600 3 magnification)
3.1.13 working distance—the distance between the bottom
of the objective lens and the sample.
4. Significance and Use
4.1 The purpose of this test method is to define a procedure
for testing components being considered for installation into a
high-purity gas distribution system. Application of this test
method is expected to yield comparable data among compo-
nents tested for purposes of qualification for this installation.
5. Apparatus
5.1 Materials:
5.1.1 Mounting Stubs, specific to the instrument used are
required.
5.1.2 Adhesives, must be vacuum stable, to attach samples
to sample stubs. Any adhesive that provides a conductive path
is acceptable.
5.1.3 Photomicrosamples, must include the following infor-
FIG. 2 Example of Pit Defect (3600 3 magnification)
mation through the use of electronic notation on the SEM
screen or ink on the back of the photomicrograph: sample
3.1.8 sample angle—that angle measured normal to the identification, magnification, and date.
5.1.4 Scale Marker, (calibration bar) must be present and
incoming electron beam.
3.1.9 scratch— a one-dimensional defect on the surface clearly visible on all photographs.
such as a line on the surface. 5.2 Instrumentation:
3.1.9.1 Discussion—For this type of defect, the depth of the 5.2.1 Scanning Electron Microscope (SEM)— The SEM
defect is no deeper than the width of the defect. used for this study should have a minimum point-to-point
3.1.10 standard conditions—101.3 kPa, 0.0°C (14.73 psia, resolution of 30 nm as measured with NIST Standard SRM
32.0°F). 20696 or equivalent.Ahigh resolution commercially available
3.1.11 stepped grain boundary—a grain boundary that has SEM with photographic capabilities is recommended.The hard
been etched to form a sudden change in height between copy photomicrographic medium from which the defect count
adjacent grains. is taken must have an area of 100 cm .
3.1.12 stringer—in wrought materials, an elongated con- 5.2.2 Instrument Operating Parameters, shall be as follows:
figuration of microconstituents or inclusions aligned in the accelerating voltage, 20 KeV; working distance, 10 to 30 mm;
direction of working (see Fig. 3). sample tilt, 0°; and, final aperture size, 150 µm or
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