ASTM F615M-95(2002)

Standard Practice for Determining Safe Current Pulse-Operating Regions for Metallization on Semiconductor Components [Metric]

SCOPE
1.1 This practice covers procedures for determining operating regions that are safe from metallization burnout induced by current pulses of less than 1-s duration.
Note 1—In this practice, "metallization" refers to metallic layers on semiconductor components such as interconnect patterns on integrated circuits. The principles of the practice may, however, be extended to nearly any current-carrying path. The term "burnout" refers to either fusing or vaporization.
1.2 This practice is based on the application of unipolar rectangular current test pulses. An extrapolation technique is specified for mapping safe operating regions in the pulse-amplitude versus pulse-duration plane. A procedure is provided in Appendix X2 to relate safe operating regions established from rectangular pulse data to safe operating regions for arbitrary pulse shapes.
1.3 This practice is not intended to apply to metallization damage mechanisms other than fusing or vaporization induced by current pulses and, in particular, is not intended to apply to long-term mechanisms, such as metal migration.
1.4 This practice is not intended to determine the nature of any defect causing failure.
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 and health practices and determine the applicability of regulatory limitations prior to use.

General Information

• Status: Historical
• Publication Date: 14-May-1995
• Technical Committee: F01 - Electronics
• Drafting Committee: F01.11 - Nuclear and Space Radiation Effects

Relations

• Replaces: ASTM F615M-95 - Standard Practice for Determining Safe Current Pulse-Operating Regions for Metallization on Semiconductor Components [Metric]
• Effective Date: 15-May-1995
• Replaced By: ASTM F615M-95(2008) - Standard Practice for Determining Safe Current Pulse-Operating Regions for Metallization on Semiconductor Components (Metric)
• Effective Date: 15-Jun-2008

Standards Content (Sample)

NOTICE: This standard has either been superseded and replaced by a new version or withdrawn.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:F 615M–95 (Reapproved 2002)
Standard Practice for
Determining Safe Current Pulse-Operating Regions for
Metallization on Semiconductor Components (Metric)
This standard is issued under the fixed designation F 615M; 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 (e) indicates an editorial change since the last revision or reapproval.
1. Scope 3.2 The d-c resistance of each specimen is measured.
3.3 Each specimen is subjected to stress from rectangular
1.1 This practice covers procedures for determining operat-
current pulses varying in amplitude and duration according to
ingregionsthataresafefrommetallizationburnoutinducedby
a predetermined schedule of pulse width and amplitudes.
current pulses of less than 1-s duration.
3.4 A second d-c resistance measurement is made on each
NOTE 1—In this practice, “metallization” refers to metallic layers on
specimen after each pulse, and it is characterized as having
semiconductor components such as interconnect patterns on integrated
failed or survived.
circuits. The principles of the practice may, however, be extended to
3.5 The number, x, of specimens surviving and the total
nearly any current-carrying path. The term “burnout” refers to either
number, n, of specimens tested at each pulse width and
fusing or vaporization.
amplitude are analyzed statistically to determine the burnout
1.2 This practice is based on the application of unipolar
level at each test pulse width for the desired burnout survival
rectangular current test pulses. An extrapolation technique is
probability and confidence level.
specified for mapping safe operating regions in the pulse-
3.6 A point corresponding to the burnout level (at the
amplitudeversuspulse-durationplane.Aprocedureisprovided
desired probability and confidence level) is plotted for each of
in Appendix X2 to relate safe operating regions established
the test pulse duration values in the pulse-amplitude, pulse-
from rectangular pulse data to safe operating regions for
duration plane. Based on these points, an extrapolation tech-
arbitrary pulse shapes.
nique is used to plot the boundary of the safe operating region.
1.3 This practice is not intended to apply to metallization
3.7 Thefollowingitemsarenotspecifiedbythepracticeand
damage mechanisms other than fusing or vaporization induced
are subject to agreement by the parties to the test:
by current pulses and, in particular, is not intended to apply to
3.7.1 The procedure by which the specimens are to be
long-term mechanisms, such as metal migration.
selected.
1.4 This practice is not intended to determine the nature of
3.7.2 Test patterns that will be representative of adjacent
any defect causing failure.
metallization on a die or wafer (5.3).
1.5 This standard does not purport to address all of the
3.7.3 The schedule of pulse amplitudes and durations to be
safety concerns, if any, associated with its use. It is the
applied to the test samples (9.8).
responsibility of the user of this standard to establish appro-
3.7.4 The level of probability and confidence to be used in
priate safety and health practices and determine the applica-
calculations to establish the boundary of the safe operating
bility of regulatory limitations prior to use.
region (10.1).
3.7.5 Theamountofchangeofresistancethatwilldefinethe
2. Terminology
criterion for failure.
2.1 Definitions of Terms Specific to This Standard:
3.7.6 The statistical model to be used to determine the
2.1.1 failure—a change in the measured resistance of
burnout probability at a desired stress level.
610% DR/R or as agreed upon by the parties to the test.
3.7.7 The form and content of the report.
3. Summary of Practice
4. Significance and Use
3.1 Specimensareselectedfromthepopulationbeingevalu-
4.1 Solid-state electronic devices subjected to stresses from
ated.
excessive current pulses sometimes fail because a portion of
the metallization fuses or vaporizes (suffers burnout). Burnout
This practice is under the jurisdiction ofASTM Committee F01 on Electronics
susceptibility can vary significantly from component to com-
and is the direct responsibility of Subcommittee F01.11 on Nuclear and Space
ponent on a given wafer, regardless of design. This practice
Radiation Effects.
Current edition approved Dec. 10, 2002. Published December 2002. Originally
approved in 1995. Last previous edition approved in 1995 as F615M-95.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
F 615M–95 (2002)
providesaprocedureforestablishingthelimitsofpulsecurrent 6.1.1 Risetimeandfalltimelessthan10%ofthepulsewidth
overstress within which the metallization of a given device (full width at half maximum amplitude (FWHM)),
should survive. 6.1.2 Impedance high enough with respect to the specimen
4.2 This practice can be used as a destructive test in a metallization so that the pulse amplitude remains constant to
lot-sampling program to determine the boundaries of the safe within 65% between the end of the rise and beginning of the
operating region having desired survival probabilities and fall,
statisticalconfidencelevelswhenappropriatesamplequantities 6.1.3 Jitterinthepulseamplitudeandwidthlessthan65%,
and statistical analyses are used. 6.1.4 Current amplitude and pulsewidth capability to pro-
vide pulses as agreed upon by the parties to the test, and
NOTE 2—The practice may be extended to infer the survivability of
6.1.5 Single-pulse capability.
untested metallization adjacent to the specimen metallization on a
semiconductor die or wafer if care is taken that appropriate similarities
NOTE 6—Refer to Appendix X2 for information relating a rectangular
exist in the design and fabrication variables.
pulse to an arbitrary pulse structure.
5. Interferences
6.2 Pulse-Monitoring Equipment, as follows:
6.2.1 Voltage-MonitoringKelvinProbe,foruseinthecircuit
5.1 The level at which failure of metallization subjected to
of Fig. 1, with risetime less than or equal to 5% of the
pulsed-current overstress occurs may be dependent on the
pulsewidth of the shortest pulse to be applied, and shunt
temperature experienced by the semiconductor device. If
capacitance sufficiently low so that the pulse shape is not
significant differences in ambient temperature or heat sinking,
distorted more than specified in 6.1:
orboth,existbetweenonetestsituationandanother,theresults
6.2.2 Voltage-Monitoring Resistor (R, Fig. 1), with suffi-
may not be representative.
ciently low inductance, resistance, and shunt capacitance so
NOTE 3—See Appendix X1 for a discussion of factors related to
that the generated pulse is not distorted more than specified in
metallization heat sinking.
6.1 and the value of the resistance is known within 61%.
5.2 Ifprobesareusedtocontactthemetallizationspecimen,
6.2.3 Current Probe, for use in the circuit of Fig. 2, with
suitable precautions must be taken or the results may be
risetime less than or equal to 5% of the pulsewidth of the
misleading. The probes must not be allowed to come into
shortest pulse to be applied, with an ampere-second product
contact with the area of metallization being characterized.
sufficient to ensure nonsaturation for the amplitudes and
5.2.1 The use of Kelvin probe connections to make the
durations of the pulses to be used and accurate within 65%.
resistance measurements is usually required to prevent contact
6.3 Pulse-Recording Equipment, transient digitizer, oscillo-
resistance (at the current injection point) from interfering with
scope with camera, storage oscilloscope, or other pulse record-
the measurement.
ing means having a risetime less than 5% of the width of the
5.2.2 Probe contacts with excessive contact resistance may
shortesttestpulseusedandcapableofrecordingindividualtest
cause damage at the point of contact. Such damage can
pulses.
interfere with the measurement.
6.4 Test Fixture,providingmeansforthecurrentpulsetobe
5.3 If the test is used to infer the survivability of metalliza-
transmitted through the metallization specimen as well as
tion on a wafer or die, the results could be misleading unless
through an equivalent resistance (see 9.5) without distortion of
such factors as the following are identical: (1) metallization
the pulse shape beyond that specified in 6.1. The test fixture
design geometry, (2) oxide step geometry, and (3) orientation
must also provide a means for connecting the metallization
of the metallization paths and oxide steps to the metallization
specimentotheresistance-measuringequipment(see6.5).The
source during deposition.
test fixture will contact the specimen through either standard
component package leads or wafer probes. More than one test
NOTE 4—The design and fabrication factors listed in 5.3 have been
fixture may be used.
shown to be important for systems of aluminum metallization deposited
on SiO /Si substrates.They are given as examples and are not intended to 6.5 Resistance-Measuring Equipment—A curve tracer,
be all inclusive or necessarily to apply to all metallization systems to
ohmmeter, or other means to be used for evaluating the d-c
which this practice may be applied.
resistance and continuity of the current path on the specimen.
NOTE 5—Variations in oxide step geometry must be expected (see
The current through the specimen during this measurement
X1.4.2).
should be minimized (less than 10% of the d-c current rating
5.4 A step-stress pulsing schedule is not recommended. If
of the specimen).
such a schedule is used so that each specimen is subjected to
successive pulses of increasing amplitude until failure occurs,
theresultscouldbemisleading.Itispossiblethatapulseofthe
proper level can cause melting at a defect site without causing
an open circuit; the molten metal may become redistributed so
that the defect appears cured and will lead to failure on
successive pulses.
6. Apparatus
6.1 Current-Pulse Generator—Asource of rectangular cur-
FIG. 1 Pulsing Circuit Using Resistor Voltage Drop to Monitor
rent pulses capable of meeting the following requirements: Current Through Specimen
F 615M–95 (2002)
9.9 Measureandrecordthespecimenresistance(see9.3and
9.4).
9.10 Compare the value recorded in 9.9 with that recorded
in 9.4. Characterize the specimen as failed if
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