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SEMI F73-1102 © SEMI 2002 4 collection effici ency. Any adhesives used to mount samples must not contam inate the surface to be analyzed. To remove loosely adhe red surface particles, the sample may be blown off immedia …

SEMI F73-1102 © SEMI 2002 3

Kβ peak with Fe Kα peak interferes with determination

of low levels of Manganese in Iron-Chromium matrix.

8 Apparatus

8.1 Instrumentation — Any SEM instrument used for

this method must be capable of a minimum point-to-

point resolution of 30 nm, as measured with a NIST

traceable standard. Any commercially available SEM

with image recording capabilities of at least 100 cm

image and an EDS analyzer capable of 170 eV or less

FWHM resolution for Mn Kα may be employed.

8.2 The SEM shall have a sample stage capable of

aligning the sample to provide multiple areas of view

with the orientation of the electron beam approximately

normal to the surface, and to optimize secondary

electron and X-ray signal collection efficiencies.

8.3 Grid Overlay — A transparent grid overlay of grid

size equal to 1.814 micrometers multiplied by the pre-

selected magnification in the range 3000 to 3600 (grid

size would be 6.35 mm [= ¼ inch] square for 3500×

magnification). The grid lines shall be as fine as

possible but clearly visible. The grid overlay shall be

designed to overlay the image of a photomicrograph

with 252 grids (18 by 14 grids for the 3.5 by 4.5 inch

image of a standard Polaroid photomicrograph) with

minimal interference from alphanumeric information

recorded with the photomicrograph, but without

reference to any features in the photomicrograph. The

rows and columns of the grid overlay may be indexed

with alphanumerics to identify and locate specific

features in the photomicrographs (see examples in

Appendices 1 and 2). It is suggested that a fixed

reference point for the edges of the photomicrograph be

established to be consistently used in all overlays.

9 Reagents and Materials

9.1 Sample Preparation Materials — Equipment

required to section the test specimen without damaging

or contaminating the surfaces to be analyzed. A clean,

dry hacksaw or dry bandsaw is recommended, using a

slow cutting speed to avoid excessive sample heating.

9.2 Sample Mounting Materials — Sample mounting

holders specific to the SEM instrument used.

Conductive paste or tape used to adhere the sample to

the holder must be vacuum stable and applied so that

the area of analytical interest is not contaminated.

10 Safety Precautions

4 National Institute of Standards and Technology, 100 Bureau Drive,

Stop 3460,Gaithersburg, MD 20899, (301) 975-NIST (6478) TTY (301)

975-8295, website: www.nist.gov.

10.1 This test method does not purport to address the

safety considerations associated with use of high

voltage, vacuum, electron and X-ray producing

equipment.

10.2 The method assumes a SEM and EDS analyst

with adequate skill level as well as knowledge of

instrumentation and associated safety precautions.

11 Test Specimen

11.1 Specimens are to be sectioned to appropriate size

for the particular SEM instrument. Any sample

preparation technique used shall avoid introducing

contamination onto the surface to be measured. In

addition, preparation must avoid heating of the sample

in excess of approximately 100°C to avoid oxide

growth or change in surface composition. Slow speed

dry cutting is recommended.

11.2 After preparation, samples shall be protected from

contamination by means such as sealing in

noncontaminating bags or wrapping in clean aluminum

foil. Appropriate cleaning of the analysis surface to

remove sample preparation residues is allowed but not

required. Any such cleaning procedures should be

stated in the report. After sectioning, samples should

be analyzed promptly.

11.3 The samples shall be analyzed in the uncoated

condition; ie, without sputtering with a conductive

coating.

12 Preparation of Apparatus

12.1 The SEM shall be in good condition to assure

proper performance in accordance with the

manufacturer’s specifications.

13 Calibration and Standardization

13.1 Instrument calibration for magnification and EDS

performance shall be performed in accordance with

ASTM E 766 and ANSI-IEEE 759 and/or the

instrument manufacturer’s recommendations. The

magnification should be calibrated at the working

distance selected. Calibration frequency shall be per

instrument manufacturer’s recommendations.

14 Procedure

14.1 The sample is to be mounted in accordance with

manufacturer' s recommendations and in a manner

consistent with high vacuum analytical procedures. The

sample shall be oriented such that the areas of interest

for SEM imaging can be viewed at 70 to 90° incidence

angle of the electron beam to the surface with optimum

secondary electron collection efficiency, and the ability

to re-orient the sample for optimization of X-ray

SEMI F73-1102 © SEMI 2002 4

collection efficiency. Any adhesives used to mount

samples must not contaminate the surface to be

analyzed. To remove loosely adhered surface particles,

the sample may be blown off immediately before

introduction into the SEM with clean, dry, 0.1

micrometer filtered gas.

14.2 Place the sample in the SEM chamber for

pumpdown. Activate the electron beam when vacuum

conditions meet manufacturer’s recommendations. The

instrument accelerating voltage should be a consistently

selected value within the range 15 to 25 Kev; 20 KeV is

suggested. The working distance should be within the

range recommended by the instrument manufacturer.

Sample position (tilt angle and orientation) may be

adjusted to optimize EDS detector collection efficiency

for EDS analysis.

14.3 Increase the magnification to ≥ 400× for initial

focus; adjust instrument parameters for astigmatism and

other anomalies. Decrease magnification to 200× and

move the sample while viewing until an area judged as

representative of the whole is in view. The area to be

analyzed should be as free of particles and defect

features produced by sample preparation as possible.

14.4 Refocus and record images of this area at 200×,

1000×, and a pre-selected, consistently used

magnification within the range 3000 to 3600×. Move

to another representative area and record an image at

the same 3000–3600× magnification. Move to a third

representative area and record another image at the

3000–3600× magnification.

14.5 Each area selected for recording should include a

defect or metallurgical feature to demonstrate proper

focusing, contrast adjustment and resolution capability.

Contrast adjustment should be performed per the

technique described in Section 4.7.2.1 of Scanning

Electron Microscopy and X-Ray Microanalysis.

All

defects and/or features for which the change in signal

∆S due to the contrast exceeds the noise N by a factor

of 5 minimum must be clearly distinguishable in the

image recorded (see Section 4.5 of reference 5).

14.6 If any inclusions or contamination are noted in the

3000–3600× images, EDS analysis of representative

defect(s) may be performed if requested by the

company for which the test method is performed.

Collect X-ray signals for a sufficient length of time to

obtain an integrated count of ≥ 250,000 within the

range of 0 to 10 keV.

5 Scanning Electron Microscopy and X-Ray Microanalysis: A Text

for Boilogists, Materials Scientists, and Geologists; Joseph I.

Goldstein, Dale E. Newbury, Patrick Echlin, David C. Joy, A. D.

Romig, Jr., Charles E. Lyman, Charles Fiori, Eric Lifshin; Second

Edition, Plenum Press, New York (1992).

15 Calculations or Interpretation of Results

15.1 The 3000–3600× recorded images shall be placed

under the transparent overlay grid. The number of grid

squares that contain all or part of a surface defect shall

be counted and summed for each photomicrograph.

Each such grid square shall only be counted once; it is

not the intent of this Test Method to count individual

defects. If a defect appears in more than one adjacent

grid square, each grid square occupied shall be counted.

NOTE 2: Examples of scanning electron micrographs

overlaid with an alphanumeric indexed grid showing specific

types of defects with comments on their locations and

whether they should be counted may be viewed at

http://www.semi.org/web/wstandards.nsf/url/SurfaceAnalysis

Examples.

15.2 Surface film residues resulting from improper

cleaning are generally diffuse and difficult to quantify.

These residues, if present, are counted as one per

image. Particles that loosely adhere to the surface must

be presumed to be artifacts of sample preparation or

exposure, and therefore shall be ignored.

15.3 Peaks appearing in the EDS spectra shall be

identified and the spectra labeled to indicate whether it

is a representative area, or identified as a defect from a

photomicrograph.

16 Reporting Results

16.1 A tabular summary of defects counted per 3000–

3600× photomicrograph shall be presented.

Additionally, the table should indicate an average of

defect counts and the maximum from the three 3000–

3600× images. An example of a table reporting defect

counting results and the photomicrographs from which

the defect counts were taken are shown in Appendix 1.

16.2 All photomicrographs are to be permanently

labeled with sample identification, magnification, a

magnification scale bar, date, and analyst identification.

The photomicrographs should be available for

inspection upon request.

16.3 EDS spectra are to be labeled with the same

information, plus peak identifications. If any

instrument parameters (e.g., tilt angle) were changed for

EDS analysis, these must be noted. If peak height

differences are such that adequate representation of all

peaks cannot be made from the same plot, two plots

having different scaling shall be included.

Identification of each defect analyzed, either by arrow

on photomicrograph or by notation of grid position,

shall be made.

17 Related Documents

17.1 ASTM Standards

ASTM F1372-93 — Standard Test Method for Scanning Electron Microscope (SEM) Analysis of Metallic Surface

Condition for Gas Distribution System Components

ASTM F1375-92 — Standard Test Method for Energy Dispersive X-Ray Spectrometer (EDX) Analysis of Metallic

Surface Condition for Gas Distribution System Components