JEDEC
PUBLICATION
Guideline for Characterizing
Solder Bump Electromigration
under Constant Current and
Temperature Stress
JEP154
JANUARY 2008
(Reaffirmed: JUNE 2011)
JEDEC SOLID STATE TECHNOLOGY ASSOCIATION
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JEDEC Publication No. 154
-i-
Guideline for Characterizing Solder Bump Electromigration under Constant Current and Temperature
Stress
Contents
1 Scope ...............................................................................................................................................................1
2 Introduction ......................................................................................................................................................1
2.1 Bump electromigration failure mechanism ..............................................................................................................1
2.2 Model for solder bump electromigration..................................................................................................................1
2.3 Overview of the test .................................................................................................................................................2
3
Terms and Definitions.......................................................................................................................................2
4 Test structures...................................................................................................................................................3
4.1 Materials and process factors ...................................................................................................................................3
4.2 Bump geometry and structures.................................................................................................................................3
4.3 Distribution of current to the bump(s)......................................................................................................................3
4.4 Resistance of the test structure .................................................................................................................................4
4.5 Types of test structures.............................................................................................................................................4
4.5.1 Single-bump structures.............................................................................................................................................4
4.5.2 Daisy Chains ............................................................................................................................................................5
4.6 Electromigration of the interconnect ........................................................................................................................7
4.7 Bump polarity...........................................................................................................................................................7
4.8 Joule heating and temperature measurement............................................................................................................7
5
Stress conditions ...............................................................................................................................................8
5.1 Current density .........................................................................................................................................................8
5.2 Temperature .............................................................................................................................................................9
6
Temperature calibration and measurement .........................................................................................................9
6.1 Calibrating the oven .................................................................................................................................................9
6.2 Calibrating the temperature sensing devices (temperature sensors) .........................................................................9
6.2.1 Resistors ...................................................................................................................................................................9
6.2.2 Diodes ....................................................................................................................................................................10
6.2.3 EM devices as temperature sensors........................................................................................................................10
6.3 Determining the temperature rise of the EM devices .............................................................................................10
6.3.1 Temperature variation across the die......................................................................................................................11
6.4 Setting the oven temperature..................................................................................................................................11
7
Performing the test..........................................................................................................................................11
7.1 Sample size ............................................................................................................................................................11
7.2 Preconditioning ......................................................................................................................................................11
7.3 Arranging the samples in the oven .........................................................................................................................12
7.4 Resistance measurement.........................................................................................................................................12
7.5 Test duration and resistance monitoring.................................................................................................................12
7.6 Setting the failure criterion.....................................................................................................................................13
7.6.1 Percentage increase in resistance............................................................................................................................13
7.6.2 Actual increase in resistance ..................................................................................................................................13
7.6.3 Absolute resistance.................................................................................................................................................14
7.7 Test details to be included in report .......................................................................................................................14
8
Data analysis ..................................................................................................................................................15
8.1 Choosing the failure distribution............................................................................................................................15
8.1.1 Lognormal distribution...........................................................................................................................................15
8.1.2 Weibull distribution................................................................................................................................................15
8.1.3 Cautions in choosing the failure distribution..........................................................................................................16
8.1.4 Cautions for 3-parameter distributions...................................................................................................................16
8.2 Special considerations for analysis of chain data ...................................................................................................16
8.3 Assigning cumulative distribution function (CDF) values to the failure data ........................................................17
8.4 Plotting the data......................................................................................................................................................18
8.5 Dealing with bimodal distributions ........................................................................................................................19
8.6 Extracting model parameters..................................................................................................................................19
9
Failure Analysis / Physical Analysis ................................................................................................................20
10 References......................................................................................................................................................22
Annex A .......................................................................................................................................................................24
JEDEC Publication No. 154
-ii-
JEDEC Publication No. 154
Page 1
GUIDELINE FOR CHARACTERIZING SOLDER BUMP ELECTROMIGRATION UNDER
CONSTANT CURRENT AND TEMPERATURE STRESS
(From JEDEC Board Ballot JCB-07-109, formulated under the cognizance of the JC-14.1 Subcommittee
on Reliability Test Methods for Packaged Devices.)
1 Scope
This document describes a method to test the electromigration (EM) susceptibility of solder bumps,
including other types of bumps, such as solder capped copper pillars, used in flip-chip packages. The
method is valid for Sn/Pb eutectic, high Pb, and Pb-free solder bumps. The document discusses the
advantages and concerns associated with EM testing, as well as options for data analysis. The tests are
performed on packaged bump electromigration test devices. The bump electromigration test techniques
described in this document can be used to assess the electromigration reliability of different types of
solder bumps and metallizations, to make materials decisions, and to establish maximum bump current
specifications. Thermal migration is also known to exist, but is outside the scope of this document.
2 Introduction
2.1 Bump electromigration failure mechanism
Electromigration of solder bumps is a failure mechanism that leads to increased resistance sometimes
accompanied by events such as formation of intermetallic compounds (IMC), voids and cracks that can
disrupt the solder joint and silicon and/ or package metallization leading into the bump. The resistance
increase can ultimately lead to an open circuit. The stress drivers for this failure mechanism are current
density and elevated temperature. The failure mechanisms for bump electromigration can be varied and
depend on the metals present both on the silicon side and the substrate side.
2.2 Model for solder bump electromigration
Black’s model (equation 1), which has been applied for many years to semiconductor die metallization,
has also been applied to solder bump electromigration [1].
(1)
This equation contains a model parameter relating to temperature (T): the thermal activation energy, E
a
. It
also contains a model parameter relating to current density (J): the current density exponent, n. In order
to verify that Black’s model applies to the type of bump structures being tested, or to derive a new model,
testing at multiple stress temperatures and current densities is needed. Extraction of these model
parameters from the test results is addressed later in this publication.
⎟
⎠
⎞
⎜
⎝
⎛
∝
−
kT
E
JTTF
a
n
exp
