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ASTM E1636-04

(Practice)

Standard Practice for Analytically Describing Sputter-Depth-Profile Interface Data by an Extended Logistic Function

Standard Practice for Analytically Describing Sputter-Depth-Profile Interface Data by an Extended Logistic Function

SIGNIFICANCE AND USE
Information on interface composition is frequently obtained by measuring surface composition while the specimen material is gradually removed by ion bombardment (see Guide E 1127 and Practice E 1162). In this way, interfaces are revealed and characterized by the measurement of composition versus depth to obtain a sputter-depth profile. The shape of such interface profiles contains information about the physical and chemical properties of the interface region. In order to accurately and unambiguously describe this interface region and to determine its width (see Guide E 1438), it is necessary to define the shape of the entire interface profile with a single analytic function.
Although no general physical model currently exists for describing the shape of interface sputter-depth profiles, interface profiles do have a sigmoidal shape characteristic of the cumulative logistic distribution. Use of such a logistic function is physically plausible and is superior to other functions (for example, polynomials) that have heretofore been used for interface profile analysis in that it contains the minimum number of parameters for describing interface shapes.
Many attempts have been made to characterize interface profiles with general functions (such as polynomials or error functions) but these have suffered from instabilities and an inability to handle poorly structured data. Choice of the logistic function along with a specifically written least-squares procedure (described in Appendix X1) can provide statistically evaluated parameters that describe the width, asymmetry, and depth of interface profiles in a reproducible and unambiguous way.
SCOPE
1.1 This practice covers a systematic method for analyzing sputter-depth-profile interface data and for accurately characterizing the shape of the interface region. Interface profile data are described with an appropriate analytic function; the parameters of this function define the interface width, its asymmetry, and its depth from the original surface. The use of this practice is recommended in order that the shapes of composition profiles of interfaces acquired with different instruments and techniques on different materials can be unambiguously compared and interpreted.  
1.2 This practice is intended to be used to describe the shape of depth profile data obtained at an interface between two dissimilar materials for that case in which the measured concentration of the outer material goes from 100 to 0% and the inner material goes from 0 to 100%.  
1.3 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
31-Oct-2004
ICS
71.040.50 - Physicochemical methods of analysis
Technical Committee
E42 - Surface Analysis
Drafting Committee
E42.08 - Ion Beam Sputtering
Current Stage
Ref Project

Relations

Replaces
ASTM E1636-94(1999) - Standard Practice for Analytically Describing Sputter-Depth-Profile Interface Data by an Extended Logistic Function
Effective Date
01-Nov-2004
Replaced By
ASTM E1636-10 - Standard Practice for Analytically Describing Depth-Profile and Linescan-Profile Data by an Extended Logistic Function (Withdrawn 2019)
Effective Date
01-Jan-2010
Referred By
ASTM E1127-08(2015) - Standard Guide for Depth Profiling in Auger Electron Spectroscopy
Effective Date
01-Nov-2004
Referred By
ASTM E2735-14(2020) - Standard Guide for Selection of Calibrations Needed for X-ray Photoelectron Spectroscopy (XPS) Experiments
Effective Date
01-Nov-2004

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ASTM E1636-04 - Standard Practice for Analytically Describing Sputter-Depth-Profile Interface Data by an Extended Logistic FunctionASTM E1636-04 - Standard Practice for Analytically Describing Sputter-Depth-Profile Interface Data by an Extended Logistic Function
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ASTM E1636-04 - Standard Practice for Analytically Describing Sputter-Depth-Profile Interface Data by an Extended Logistic Function
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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: E1636 – 04
Standard Practice for
Analytically Describing Sputter-Depth-Profile Interface Data
1
by an Extended Logistic Function
This standard is issued under the fixed designation E1636; 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 3. Terminology
1.1 This practice covers a systematic method for analyzing 3.1 Definitions—For definitions of terms used in this prac-
sputter-depth-profile interface data and for accurately charac- tice, see Terminology E673.
terizing the shape of the interface region. Interface profile data 3.2 Definitions of Terms Specific to This Standard:
aredescribedwithanappropriateanalyticfunction;theparam- 3.2.1 Throughout this practice, the regions of the sigmoidal
eters of this function define the interface width, its asymmetry, profile will be referred to as the pre-interface, interface, and
anditsdepthfromtheoriginalsurface.Theuseofthispractice post-interface regions. These terms are not dependent on
is recommended in order that the shapes of composition whether a particular interface profile is a growth or a decay
profiles of interfaces acquired with different instruments and curve. The terms pre- and post- are taken in the sense of
techniques on different materials can be unambiguously com- increasing values of the independent variable X, the sputtered
pared and interpreted. depth.
1.2 Thispracticeisintendedtobeusedtodescribetheshape
4. Summary of Practice
of depth profile data obtained at an interface between two
dissimilar materials for that case in which the measured 4.1 Sputter depth profile interface data (composition versus
depth) is fitted to an analytic function, an extended form of the
concentration of the outer material goes from 100 to 0% and
the inner material goes from 0 to 100%. logistic function, in order to describe the shape of such
3
interface profiles. Least-squares fitting techniques are em-
1.3 This standard does not purport to address all of the
safety concerns, if any, associated with its use. It is the ployed to determine the values of the parameters of this
extended logistic function which characterize the shape of the
responsibility of the user of this standard to establish appro-
interface. Interface width, depth, and asymmetry are deter-
priate safety and health practices and determine the applica-
bility of regulatory limitations prior to use. mined by these parameters.
5. Significance and Use
2. Referenced Documents
2
2.1 ASTM Standards: 5.1 Information on interface composition is frequently ob-
tained by measuring surface composition while the specimen
E673 Terminology Relating to Surface Analysis
E1127 Guide for Depth Profiling in Auger Electron Spec- materialisgraduallyremovedbyionbombardment(seeGuide
E1127andPracticeE1162).Inthisway,interfacesarerevealed
troscopy
E1162 Practice for Reporting Sputter Depth Profile Data in and characterized by the measurement of composition versus
depth to obtain a sputter-depth profile. The shape of such
Secondary Ion Mass Spectrometry (SIMS)
E1438 Guide for MeasuringWidths of Interfaces in Sputter interface profiles contains information about the physical and
chemical properties of the interface region. In order to accu-
Depth Profiling Using SIMS
rately and unambiguously describe this interface region and to
determineitswidth(seeGuideE1438),itisnecessarytodefine
1
This practice is under the jurisdiction of ASTM Committee E42 on Surface
the shape of the entire interface profile with a single analytic
Analysis and is the direct responsibility of Subcommittee E42.08 on Ion Beam
function.
Sputtering.
Current edition approved Nov. 1, 2004. Published December 2004. Originally
approved in 1999. Last previous version approved in 1999 as E1636–94 (1999).
DOI: 10.1520/E1636-04.
2
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
3
contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM Kirchhoff,W. H., Chambers, G. P., and Fine, J., “AnAnalytical Expression for
Standards volume information, refer to the standard’s Document Summary page on Describing Auger Sputter Depth Profile Shapes of Interfaces,” Journal of Vacuum
the ASTM website. Science and Technology, E1438, p. 1666, 1986.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
1

---------------------- Page: 1 ----------------------
E1636 – 04
5.2 Although no general physical model currently exists for interface region; Q, an asymmetry parameter, is a measure of
describing the shape of interface sputter-depth profiles, inter- thedifferenceincurvatureinthepr
...

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5.1 Auger electron spectroscopy and X-ray photoelectron spectroscopy are used extensively for the surface analysis of materials. This practice summarizes methods for determining the specimen area contributing to the detected signal (a) for instruments in which a focused electron beam can be scanned over a region with dimensions greater than the dimensions of the specimen area viewed by the analyzer, and (b) by employing a sample with a sharp edge.  
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1.1 This practice describes methods for determining the specimen area contributing to the detected signal in Auger electron spectrometers and some types of X-ray photoelectron spectrometers (spectrometer analysis area) when this area is defined by the electron collection lens and aperture system of the electron energy analyzer. The practice is applicable only to those X-ray photoelectron spectrometers in which the specimen area excited by the incident X-ray beam is larger than the specimen area viewed by the analyzer, in which the photoelectrons travel in a field-free region from the specimen to the analyzer entrance. Some of the methods described here require an auxiliary electron gun mounted to produce an electron beam of variable energy on the specimen (“electron-gun method”). Other experiments require a sample with a sharp edge, such as a wafer covered with a uniform clean layer (for example, gold (Au) or silver (Ag)) and cleaved to obtain a long side (“sharp-edge method”).  
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5.1 Electron multipliers are commonly used in pulse-counting mode to detect ions from magnetic sector mass spectrometers. The electronics used to amplify, detect and count pulses from the electron multipliers always have a characteristic time interval after the detection of a pulse, during which no other pulses can be counted. This characteristic time interval is known as the “dead time.” The dead time has the effect of reducing the measured count rate compared with the “true” count rate.  
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SCOPE
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1.5 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, health, and environmental practices and determine the applicability of regulatory limitations prior to use.  
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