ASTM E2245-11
(Test Method)Standard Test Method for Residual Strain Measurements of Thin, Reflecting Films Using an Optical Interferometer
Standard Test Method for Residual Strain Measurements of Thin, Reflecting Films Using an Optical Interferometer
SIGNIFICANCE AND USE
Residual strain measurements are an aid in the design and fabrication of MEMS devices. The value for residual strain is used in Young’modulus calculations.
SCOPE
1.1 This test method covers a procedure for measuring the compressive residual strain in thin films. It applies only to films, such as found in microelectromechanical systems (MEMS) materials, which can be imaged using an interferometer. Measurements from fixed-fixed beams that are touching the underlying layer are not accepted.
1.2 This test method uses a non-contact optical interferometer with the capability of obtaining topographical 3-D data sets. It is performed in the laboratory.
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.
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Designation:E2245 −11
StandardTest Method for
Residual Strain Measurements of Thin, Reflecting Films
1
Using an Optical Interferometer
This standard is issued under the fixed designation E2245; 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 test method covers a procedure for measuring the 3.1 Definitions:
compressive residual strain in thin films. It applies only to
3.1.1 The following terms can be found in Terminology
films, such as found in microelectromechanical systems
E2444.
(MEMS) materials, which can be imaged using an optical
3.1.2 2-D data trace, n—a two-dimensional group of points
interferometer,alsocalledaninterferometricmicroscope.Mea-
that is extracted from a topographical 3-D data set and that is
surements from fixed-fixed beams that are touching the under-
parallel to the xz-or yz-plane of the interferometric micro-
lying layer are not accepted.
scope.
1.2 This test method uses a non-contact optical interfero-
3.1.3 3-D data set, n—a three-dimensional group of points
metricmicroscopewiththecapabilityofobtainingtopographi-
with a topographical z-value for each (x, y) pixel location
cal 3-D data sets. It is performed in the laboratory.
within the interferometric microscope’s field of view.
1.3 This standard does not purport to address all of the
3.1.4 anchor, n—in a surface-micromachining process, the
safety concerns, if any, associated with its use. It is the
portion of the test structure where a structural layer is inten-
responsibility of the user of this standard to establish appro-
tionally attached to its underlying layer.
priate safety and health practices and determine the applica-
bility of regulatory limitations prior to use. 3.1.5 anchor lip, n—in a surface-micromachining process,
the freestanding extension of the structural layer of interest
2. Referenced Documents
around the edges of the anchor to its underlying layer.
2
3.1.5.1 Discussion—In some processes, the width of the
2.1 ASTM Standards:
anchor lip may be zero.
E2244Test Method for In-Plane Length Measurements of
Thin, Reflecting Films Using an Optical Interferometer
3.1.6 bulk micromachining, adj—a MEMS fabrication pro-
E2246Test Method for Strain Gradient Measurements of
cess where the substrate is removed at specified locations.
Thin, Reflecting Films Using an Optical Interferometer
3.1.7 cantilever, n—a test structure that consists of a free-
E2444Terminology Relating to Measurements Taken on
standing beam that is fixed at one end.
Thin, Reflecting Films
E2530Practice for Calibrating the Z-Magnification of an
3.1.8 fixed-fixed beam, n—a test structure that consists of a
Atomic Force Microscope at Subnanometer Displacement
freestanding beam that is fixed at both ends.
Levels Using Si(111) Monatomic Steps
3.1.9 in-plane length (or deflection) measurement, n—the
3
2.2 SEMI Standard:
experimental determination of the straight-line distance be-
MS2Test Method for Step Height Measurements of Thin
tween two transitional edges in a MEMS device.
Films
3.1.9.1 Discussion—This length (or deflection) measure-
ment is made parallel to the underlying layer (or the xy-plane
1 of the interferometric microscope).
This test method is under the jurisdiction ofASTM Committee E08 on Fatigue
and Fracture and is the direct responsibility of Subcommittee E08.05 on Cyclic
3.1.10 interferometer, n—a non-contact optical instrument
Deformation and Fatigue Crack Formation.
used to obtain topographical 3-D data sets.
Current edition approved Nov. 1, 2011. Published December 2011. Originally
approved in 2002. Last previous edition approved in 2005 as E2245–05.
3.1.10.1 Discussion—The height of the sample is measured
2
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
along the z-axis of the interferometer. The x-axis is typically
contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
aligned parallel or perpendicular to the transitional edges to be
Standards volume information, refer to the standard’s Document Summary page on
the ASTM website.
measured.
3
For referenced Semiconductor Equipment and Materials International (SEMI)
standards, visit the SEMI website, www.semi.org. 3.1.11 MEMS, adj—microelectromechanical systems.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
1
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E2245−11
3.1.12 microelectromechanical systems, adj—in general, σ =the standard deviation of the noise measurement,
noise
this term is used to describe micron-scale structures, sensors, calculate
...
This document is not anASTM standard and is intended only to provide the user of anASTM standard an indication of what changes have been made to the previous version. Because
it may not be technically possible to adequately depict all changes accurately, ASTM recommends that users consult prior editions as appropriate. In all cases only the current version
of the standard as published by ASTM is to be considered the official document.
Designation:E2245–05 Designation: E2245 – 11
Standard Test Method for
Residual Strain Measurements of Thin, Reflecting Films
1
Using an Optical Interferometer
This standard is issued under the fixed designation E2245; 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
1.1 Thistestmethodcoversaprocedureformeasuringthecompressiveresidualstraininthinfilms.Itappliesonlytofilms,such
as found in microelectromechanical systems (MEMS) materials, which can be imaged using an optical interferometer, also called
an interferometric microscope. Measurements from fixed-fixed beams that are touching the underlying layer are not accepted.
1.2 This test method uses a non-contact optical interferometeric microscope with the capability of obtaining topographical 3-D
data sets. It is performed in the laboratory.
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.
2. Referenced Documents
2
2.1 ASTM Standards:
E2244 Test Method for In-Plane Length Measurements of Thin, Reflecting Films Using an Optical Interferometer
E2246 Test Method for Strain Gradient Measurements of Thin, Reflecting Films Using an Optical Interferometer Test Method
for Strain Gradient Measurements of Thin, Reflecting Films Using an Optical Interferometer
E2444 Terminology Relating to Measurements Taken on Thin, Reflecting Films
E2530 Practice for Calibrating the Z-Magnification of an Atomic Force Microscope at Subnanometer Displacement Levels
Using Si(111) Monatomic Steps
3
2.2 SEMI Standard:
MS2 Test Method for Step Height Measurements of Thin Films
3. Terminology
3.1 Definitions:
3.1.1
3.1.1 The following terms can be found in Terminology E2444.
3.1.2 2-D data trace, n—a two-dimensional group of points that is extracted from a topographical 3-D data set and that is
parallel to the xz-or yz-plane of the interferometeric microscope.
3.1.23.1.3 3-Ddataset,n—athree-dimensionalgroupofpointswithatopographicalz-valueforeach(x,y)pixellocationwithin
the interferometer’s interferometric microscope’s field of view.
3.1.33.1.4 anchor, n—in a surface-micromachining process, the portion of the test structure where a structural layer is
intentionally attached to its underlying layer.
3.1.4
3.1.5 anchor lip, n—in a surface-micromachining process, the freestanding extension of the structural layer of interest around
the edges of the anchor to its underlying layer.
3.1.4.1
3.1.5.1 Discussion—In some processes, the width of the anchor lip may be zero.
3.1.5
1
This test method is under the jurisdiction of ASTM Committee E08 on Fatigue and Fracture and is the direct responsibility of Subcommittee E08.05 on Cyclic
Deformation and Fatigue Crack Formation.
Current edition approved Nov. 1, 2005.2011. Published December 2005.2011. Originally approved in 2002. Last previous edition approved in 20022005 as E2245–02.
DOI: 10.1520/E2245-05.E2245–05.
2
ForreferencedASTMstandards,visittheASTMwebsite,www.astm.org,orcontactASTMCustomerServiceatservice@astm.org.ForAnnualBookofASTMStandards
volume information, refer to the standard’s Document Summary page on the ASTM website.
3
The boldface numbers in parentheses refer to the list of references at the end of this standard.
3
For referenced Semiconductor Equipment and Materials International (SEMI) standards, visit the SEMI website, www.semi.org.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
1
---------------------- Page: 1 ----------------------
E2245 – 11
3.1.6 bulk micromachining, adj—a MEMS fabrication process where the substrate is removed at specified locations.
3.1.6
3.1.7 cantilever, n—a test structure that consists of a freestanding beam that is fixed at one end.
3.1.7
3.1.8 fixed-fixed beam, n—a test structure that consists of a freestanding beam that is fixed at both ends.
3.1.8
3.1.9 in-plane length (or deflection) measurement, n—the experimental determination of the straight-line distance between two
transitional edges in a MEMS device.
3.1.8.1
3.1.9.1 Discussion—This length (or deflection) measurement is made parallel to the underlying layer (or the xy-plane of
...
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