ASTM F43-99
(Test Method)Standard Test Methods for Resistivity of Semiconductor Materials (Withdrawn 2003)
Standard Test Methods for Resistivity of Semiconductor Materials (Withdrawn 2003)
SCOPE
This standard was transferred to SEMI (www.semi.org) May 2003
1.1 The resistivity of a semiconductor material is an important materials acceptance requirement. Resistivity determinations made during device fabrication are also widely used for quality control purposes.
1.2 These test methods cover two procedures which are widely used for making routine measurements. These procedures apply directly to both silicon and germanium. Application of these procedures to other semiconductor materials may require the use of different probe material and probe attachment.
1.2.1 Method A, Two-Probe -This test method requires a bar specimen of measurable cross section and with cross-sectional dimensions small in comparison with the length of the bar. For materials for which no specific ASTM referee method has been developed, this test method is recommended for materials acceptance purposes.
1.2.2 Method B, Four-Probe -This test method is rapid and does not require a specimen of regular cross section. This test method may be used on irregularly shaped specimens, provided a flat region is available for the contacting probes. As described in this standard, this test method is applicable only to specimens such that the thickness of the specimen and the distance from any probe point to the nearest edge are both at least four times the probe spacing (Note 1). For the special case of specimens of circular cross section with thickness more than one, but less than four, times the probe spacing, measurements by this test method are possible; the required application of approximate geometric corrections will result in improved accuracy (see 9.1.3).
1.2.3 In general, resistivity measurements are most reliable when made on single crystals, since with such material local variations in impurity which affect the resistivity are less severe. Localized impurity segregation at grain boundaries in polycrystalline material may result in large resistivity variations. Such effects are common to either of the measurement test methods but are more severe with the four-probe test method, and its use, therefore, is not recommended for polycrystalline material.
1.3 The values stated in SI units are to be regarded as the standard. The values given in parentheses are for information only.
1.4 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.
General Information
Relations
Standards Content (Sample)
NOTICE: This standard has either been superceded and replaced by a new version or discontinued.
Contact ASTM International (www.astm.org) for the latest information.
Designation: F 43 – 99 DIN 50431
Standard Test Methods for
Resistivity of Semiconductor Materials
This standard is issued under the fixed designation F 43; 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.
1. Scope severe. Localized impurity segregation at grain boundaries in
polycrystalline material may result in large resistivity varia-
1.1 The resistivity of a semiconductor material is an
tions. Such effects are common to either of the measurement
important materials acceptance requirement. Resistivity deter-
test methods but are more severe with the four-probe test
minations made during device fabrication are also widely used
method, and its use, therefore, is not recommended for poly-
for quality control purposes.
crystalline material.
1.2 These test methods cover two procedures which are
1.3 The values stated in SI units are to be regarded as the
widely used for making routine measurements. These proce-
standard. The values given in parentheses are for information
dures apply directly to both silicon and germanium. Applica-
only.
tion of these procedures to other semiconductor materials may
1.4 This standard does not purport to address all of the
require the use of different probe material and probe attach-
safety concerns, if any, associated with its use. It is the
ment.
responsibility of the user of this standard to establish appro-
1.2.1 Method A, Two-Probe— This test method requires a
priate safety and health practices and determine the applica-
bar specimen of measurable cross section and with cross-
bility of regulatory limitations prior to use.
sectional dimensions small in comparison with the length of
the bar. For materials for which no specific ASTM referee
2. Referenced Documents
method has been developed, this test method is recommended
2.1 ASTM Standards:
for materials acceptance purposes.
F 76 Test Methods for Measuring Resistivity and Hall
1.2.2 Method B, Four-Probe— This test method is rapid and
Coefficient and Determining Hall Mobility in Single-
does not require a specimen of regular cross section. This test
Crystal Semiconductors
method may be used on irregularly shaped specimens, pro-
F 84 Test Method for Measuring Resistivity of Silicon
vided a flat region is available for the contacting probes. As
Wafers with an In-Line Four-Point Probe
described in this standard, this test method is applicable only to
F 374 Test Method for Sheet Resistance of Silicon Epi-
specimens such that the thickness of the specimen and the
taxial, Diffused, Polysilicon, and Ion-Implanted Layers
distance from any probe point to the nearest edge are both at
Using an In-Line Four-Point Probe
least four times the probe spacing (Note 1). For the special case
F 397 Test Method for Resistivity of Silicon Bars Using a
of specimens of circular cross section with thickness more than
Two-Point Probe
one, but less than four, times the probe spacing, measurements
F 533 Test Method for Thickness and Thickness Variation
by this test method are possible; the required application of
of Silicon Slices
approximate geometric corrections will result in improved
F 613 Test Method for Measuring Diameter of Semiconduc-
accuracy (see 9.1.3).
tor Wafers
1.2.3 In general, resistivity measurements are most reliable
2.2 American National Standard:
when made on single crystals, since with such material local
B 74.10 Specification for Grading of Abrasive Microgrits
variations in impurity which affect the resistivity are less
NOTE 1—Other ASTM methods are preferred for use in various special
circumstances. For measurements on thin slices, use Test Method F 84;
These test methods are under the jurisdiction of ASTM Committee F-1 on
this method is preferred for referee measurements on silicon slices. For
Electronics and are the direct responsibility of Subcommittee F01.06 on Silicon
measurements on specimens for which point contacts are unsatisfactory,
Materials and Process Control.
use a procedure in Test Methods F 76. For two-probe referee measure-
Current edition approved Dec. 10, 1999. Published February 2000. Originally
ments on cylindrical single crystal bars, use Test Method F 397. For
published as F 43 – 64 T. Last previous edition F 43 – 93.
four-probe referee measurements of sheet resistance on epitaxial layers
DIN 50431 is an equivalent method. It is the responsibility of DIN Committee
NMP 221, with which Committee F-1 maintains close technical liaison. deposited on or diffused or implanted into opposite conductivity-type
DIN 50431, Testing of Inorganic Semiconductor Materials: Measurement of the
Specific Electrical Resistance of Monocrystals of Silicon or Germanium by the
Four-Point Direct-Current Technique with Linearly Arranged Probes, is available Annual Book of ASTM Standards, Vol 10.05.
from Beuth Verlag GmbH Burggrafenstrasse 4-10, D-1000 Berlin 30, Federal Available from American National Standards Institute, 11 West 42nd St., 13th
Republic of Germany. Floor, New York, NY 10036.
Copyright © ASTM, 100 Barr Harbor Drive, West Conshohocken, PA 19428-2959, United States.
NOTICE: This standard has either been superceded and replaced by a new version or discontinued.
Contact ASTM International (www.astm.org) for the latest information.
F43
substrates, use Test Method F 374.
possessing high minority carrier lifetime and high resistivity,
such injection can result in a lowering of the resistivity for
3. Terminology
distance of several centimetres. Carrier injection can be de-
3.1 Definitions of Terms Specific to This Standard:
tected by repeating the measurements at lower current. In the
3.1.1 resistivity, r[V·cm] of a semiconductor,— the ratio of
absence of injection no increase in resistivity should be
the potential gradient (electric field) parallel with the current to
observed. It is recommended that the current used in a
the current density.
resistivity measurement be as low as possible, consistent with
the required precision.
4. Summary of Test Methods
5.1.4 Semiconductors have a significant temperature coeffi-
4.1 Two-Probe Method—A direct current is passed through
cient of resistivity. Consequently, the temperature of the
ohmic contacts at the ends of a bar specimen and the potential
specimen should be known at the time of the measurement and
difference is determined between two probes placed along the
the current used should be small to avoid resistive heating. If
current direction (Fig. 1). The resistivity is calculated from the
resistive heating is suspected, it can be detected by a change in
current and potential values and factors appropriate to the
readings as a function of time starting immediately after the
geometry.
current is applied. Temperature correction factors for extrinsic
4.2 Four-Probe Method—An in-line four-point probe is
germanium are plotted in Fig. 2 and Fig. 3. For referee
placed on a flat surface of a solid specimen which can be
purposes, it is recommended that the test be performed at 23 6
approximated as semi-infinite. A direct current is passed
0.5°C . Temperature correction factors for silicon are plotted in
through the specimen between the outer probes and the
Fig. 4 and Fig. 5, and are given in tabular form in Test Method
resulting potential difference is measured between the inner
F 84 along with an equation for applying the correction.
probes (Fig. 1). The resistivity is calculated from the current
5.1.5 Vibration of the probes sometimes causes troublesome
and potential values and factors appropriate to the geometry.
changes in the contact resistance. If difficulty is encountered,
shock mount the apparatus.
5. Interferences
5.1 In making resistivity measurements, spurious results can
6. Apparatus
arise from a number of sources. The following must be guarded
6.1 Jigs suitable for mounting the specimens and contact-
against:
ing them with either two or four probes as required. The probes
5.1.1 Photoconductive and photovoltaic effects can seri-
shall be individually spring mounted and shall be loaded with
ously influence the observed resistivity, particularly with
a force of 1.5 6 0.5 N. The probe mountings shall be furnished
nearly intrinsic material. Therefore make all determinations in
with appropriate guides to ensure that the probes contact the
a dark chamber unless experience has shown that the material
specimen reproducibly with a probe spacing tolerance of
is insensitive to ambient illumination.
60.5 %. The probes may be made from hardened tool steel,
5.1.2 Spurious currents can be introduced in the testing
tungsten carbide, or other conducting metal and may be chisel
circuit when the equipment is located near high-frequency
shaped for measurement of curved surfaces or pointed for
generators. If equipment is located near such sources, adequate
measurement on flat sections. In the case of point probes, the
shielding must be provided.
nominal radius of the tips should be initially 25 to 50 μm. With
5.1.3 Minority carrier injection during the measurement can
all probing devices, frequent checking of the probe spacing
occur due to the electric field in the specimen. With material
with a calibrating microscope is desirable. Probes should be
replaced or resharpened when necessary to maintain the
required spacing tolerance. Isolation resistance between the
probes should be at least 10 V.
NOTE 2—Detailed procedures for in situ determination of the spacing
between adjacent probes of an in-line four-point probe are given in the
Probe Assembly paragraph of the Suitability of Test Equipment section, of
Test Method F 84. These procedures, for which equipment described in
the Probe Alignment and Separation paragraph of the Apparatus section,
of Test Method F 84 is required, can be used to establish probe spacings
and their repeatability for both two- and four-probe assemblies. The probe
spacing correction factor, F , in Equation 5 of the Suitability of Test
sp
Equipment section, of Test Method F 84 should be replaced by:
¯ ¯
F 5 1 1 1.25 @1 2 ~ S / S!#,
where:
¯
S 5 spacing between inner pair of probes, cm, and
¯
S 5 average probe spacing, cm,
when four-probe measurements are made on semi-infinite solids. In
general, however, the correction for unequal probe spacing is neglected.
6.2 The recommended electrical circuit, connected as
FIG. 1 Specimen and Probe Arrangement for Two-Probe and
Four-Probe Measurements on a Rectangular Bar shown in Fig. 6, consists of the following:
NOTICE: This standard has either been superceded and replaced by a new version or discontinued.
Contact ASTM International (www.astm.org) for the latest information.
F43
FIG. 2 Temperature Coefficient (C ) Versus Specimen Resistivity (r ) for N-Type Germanium
T av
FIG. 3 Temperature Coefficient (C ) Versus Specimen Resistivity (r ) for p-Type Germanium
T av
described in the Analog Test Circuit paragraph of the Apparatus section,
6.2.1 Constant Current Source capable of supplying cur-
−1 −5
of Test Method F 84 is required.
rents between 10 and 10 A. The current must be known
and maintained constant to 60.5 % during the measurement.
6.3 Lapping or Sandblasting Facilities to provide a flat,
6.2.2 Current Reversing Switch.
abraded surface on which the measurement is made.
6.2.3 Standard Resistor with a resistance within a factor of
6.4 Micrometer or Vernier Caliper to determine the cross-
100 of that of the specimen.
sectional area normal to the current in the two-probe method to
6.2.4 Double-Throw, Double-Pole Potential Selector
60.5 % or for measuring the dimensions of circular specimens
Switch.
with thickness more than one, but less than four, times the
6.2.5 Potentiometer-Galvanometer or Electronic Voltmeter
probe spacing in the four-probe method.
−4
—capable of measuring potential differences between 10
6.5 Thermometer or other temperature measuring instru-
and 1 V of either polarity to 60.5 %. The input impedance
ment to determine the ambient temperature to 60.5°C.
must exceed 1000 times the total contact plus bulk resistance of
7. Test Specimen
the specimen.
7.1 Two-Probe Method—The test specimen for the two-
NOTE 3—The electrical measuring circuit may also measure either
probe test method may be in the form of a strip, rod, or bar. The
resistance or current directly. Any electrical circuit that meets the
ratio of the length to the larger cross-sectional dimension of the
requirements of the Electrical Equipment part of the Suitability of Test
specimen shall be not less than 3 to 1. The cross section of the
Equipment section, of Test Method F 84 is acceptable for use in this test
specimen must be of measurable shape and should be as
method. If the procedures of Test Method F 84 are used to evaluate the
adequacy of the electrical equipment, an appropriate analog test circuit as uniform as possible. Prior to measurement, ohmic contact shall
NOTICE: This standard has either been superceded and replaced by a new version or discontinued.
Contact ASTM International (www.astm.org) for the latest information.
F43
FIG. 4 Temperature Coefficient (C ) as a Function of Specimen Resistivity (r ) for n-Type Silicon
T av
FIG. 5 Temperature Coefficient (C ) as a Function of Specimen Resistivity (r ) for p-Type Silicon
T av
be made to the ends of the specimen (for example, by
electroplating with copper or nickel or by ultrasonic soldering,
(see Note 4)). Connections to the ends may be made either with
soldered leads or pressure contacts.
NOTE 4—Alternative methods for forming ohmic contacts to germa-
nium, silicon, and gallium arsenide are given in Test Method F 76.
7.2 Four-Probe Method—One reasonably flat surface for
the contacting probes is required on the specimen which may
NOTE 1—The standard resistor and potential selector switch are not
be of any size or shape which approximates a semi-infinite
required for routine four-probe measurements if a calibrated current
solid. The conditions for a semi-infinite solid are approximated
source is used.
within 2 % when the thickness of the specimen and the FIG. 6 Recommended Electrical Circuit for Two-Probe and Four-
Probe Resistivity Measurements
distance from any probe to the nearest edge are both at least
four times the probe spacing.
7.2.1 If the specimen is of circular cross section and has
thickness more than one, but less than four, times the probe 7.2.1.1 Measure and record five values of thickness, w,at
i
spacing, measure the thickness and diameter as follows: various points near the ce
...
Questions, Comments and Discussion
Ask us and Technical Secretary will try to provide an answer. You can facilitate discussion about the standard in here.