ASTM E2444-05

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Designation: E 2444 – 05
Terminology Relating to
1
Measurements Taken on Thin, Reflecting Films
This standard is issued under the fixed designation E 2444; 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 (ε) indicates an editorial change since the last revision or reapproval.
1. Scope attached to its underlying layer (see Figs. 1-3). E 2244
anchor lip—in a surface-micromachining process, the free-
1.1 This standard consists of terms and definitions pertain-
standing extension of the structural layer of interest around
ing to measurements taken on thin, reflecting films, such as
the edges of the anchor to its underlying layer (see Fig. 2).
found in microelectromechanical systems (MEMS) materials.
In some processes, the width of the anchor lip may be zero.
In particular, the terms are related to the standards in Section 2,
E 2244
which were generated by Committee E08 on Fatigue and
bulk micromachining—a MEMS fabrication process where
Fracture.Terminology E 1823 Relating to Fatigue and Fracture
the substrate is removed at specified locations. E 2244
Testing is applicable to this standard.
cantilever—a test structure that consists of a freestanding
1.2 The terms are listed in alphabetical order.
beam that is fixed at one end (such as shown in Fig. 3).
2. Referenced Documents
E 2246
2
fixed-fixed beam —a test structure that consists of a freestand-
2.1 ASTM Standards:
E 1823 Terminology Relating to Fatigue and Fracture Test- ing beam that is fixed at both ends (such as shown in Figs.
1 and 2). E 2245
ing
E 2244 Test Method for In-Plane Length Measurements of in-plane length (or deflection) measurement, L (or D)
[L]—a length (or deflection) measurement made parallel to
Thin, Reflecting Films Using an Optical Interferometer
E 2245 Test Method for Residual Strain Measurements of the underlying layer (or the xy-plane). E 2244
interferometer—a non-contact optical instrument used to
Thin, Reflecting Films Using an Optical Interferometer
E 2246 Test Method for Strain Gradient Measurements of obtain topographical 3-D data sets. E 2244
MEMS—microelectromechanical systems. E 2244
Thin, Reflecting Films Using an Optical Interferometer
microelectromechanical systems, MEMS—in general, this
3. Terminology
term is used to describe micron-scale structures, sensors, and
3.1 Terms and Their Definitions:
actuators and/or the technologies used for their manufacture
(such as, silicon process technologies). E 2244
2-D data trace—a two-dimensional data trace that is extracted
out-of-plane measurements [L]—measurements taken on
from a topographical 3-D data set and that is parallel to the
structures that are curved out-of-plane in the z-direction (that
xz-or yz-plane of the interferometer.
is, perpendicular to the underlying layer). E 2444
DISCUSSION—The height of the sample is measured along the z-axis
residual strain, ε —in a surface-micromachining process, the
r
of the interferometer. The interferometer’s x-axis (as shown in Figs.
strain present in the structural layer of interest after fabrica-
1-3) is typically aligned parallel or perpendicular to the transitional
tion yet before the sacrificial layer is removed. In a bulk-
edges to be measured. E 2244
micromachining process, the strain present in the suspended
3-D data set—a three-dimensional data set with a topographi- layer after fabrication yet before the substrate is removed at
cal z-data value for each (x, y) pixel location within the specified locations. E 2245
interferometer’s field of view. E 2244 sacrificial layer—a layer that is intentionally deposited (or
anchor—in a surface-micromachining process, the portion of added) then removed, in whole or in part, during the
the test structure where a structural layer is intentionally micromachining process, to allow freestanding microstruc-
tures. E 2244
stiction—adhesion between the portion of a structural layer
1
This test method is under the jurisdiction ofASTM Committee E08 on Fatigue
that is intended to be freestanding and its underlying layer.
and Fracture and is the direct responsibility of Subcommittee E08.05 on Cyclic
E 2246
Deformation and Fatigue Crack Formation.
–1
Current edition approved May 1, 2005. Published May 2005.
(residual) strain gradient, s [L ]—a through-thickness lin-
g
2
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
ear gradient (of residual strain) in the structural layer of
contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
interest before it is released that is used to represent the
Standards volume information, refer to the standard’s Document Summary page on
the ASTM website.
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