4 Failure Analysis of Semiconductor
Devices
Contents
i
4.1
Importance of Failure Analysis
4- 1
4.2
Procedures for Failure Analysis
4- 1
4.2.1
Confirmation of information on failure
4- 4
4.2.2
External observation
4- 4
4.2.3
Confirmation of characteristic analysis/
failure mode
4- 4
4.2.4
Nondestructive analysis
4- 5
4.2.5
Unsealing
4- 7
4.2.6
Internal observation and measurement
4- 8
4.2.7
Search for failure locations
4-11
4.2.8
Processing technology for analyses
4-15
4.2.9
Surface microanalysis
4-17
4
4.
Failure Analysis of Semiconductor Devices
Failure Analysis of Semiconductor Devices
4.1
Importance of Failure Analysis
Failure analysis is the process of investigating semiconductor devices after failure by electric measurement,
and by physical and chemical analysis techniques if necessary, to confirm the reported failure and clarify the
failure mode or mechanism.
Progress of semiconductor devices has rapidly accelerated toward high integration, high density and high
functionality. In addition, use applications are widely penetrated into various civil and industrial fields.
Our company tries to consider high reliability through the design, development and manufacturing processes
of semiconductor devices with the goal of “zero failures” and to provide those products to customers.
However, it is impossible to eliminate all failures.
So, our company analyzes failures occurring during the manufacturing process, reliability test, mounting
process at the customer’s site and in the market (field), investigates the failure mechanism and cause thoroughly,
and feeds them back to each department in charge to prevent a failure from recurring.
4.2
Procedures for Failure Analysis
Figure 4.1 and Table 4.1 respectively show the procedures for failure analysis and an example of devices
to be used. When conducting failure analysis, it is recommended to adopt unified procedures, and it is
important to promote failure analysis so as to obtain information required to determine the failure mechanism.
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Failure Analysis of Semiconductor Devices
Arising failure
Source
origin
Confirmation of
failure information
Product class name
Manufacturing code
Status of use
Symptom of failure
Discoloration/deformation
Attachment of foreign substances
Crack
External observation
Check according to product specifications
Operation according to application circuits
V-I between terminals
Vibration
Heating
Cooling
Condition change of characteristic operation
Damaged circuit analysis
Characteristic analysis
Baking
X-ray fluoroscopy
Ultrasonic flaw detection analysis
Nondestructive
analysis
Mechanical unsealing
Chemical solution
Plasma etching
Unsealing
Probe static characteristic measurement
Probe dynamic characteristic measurement
Confirmation of
symptoms
Microscopic observation
Photomicrography
Cross-section photograph
Video monitor
Liquid crystal analysis
Microscopic
observation
SEM
analysis
Probe determination
Secondary electron image
Reflection electron image
Voltage contrast image
Electromotive force image
EB tester
Etching/lapping
Detailed chemical
physical analysis
EPMA
SIMS
AES
Analysis result
Feedback
Figure 4.1
T04007BE-4 2009.4 4-2
Reliability test
Process
Burn-in
Market
Procedures of failure analysis
4
Table 4.1
Failure Analysis of Semiconductor Devices
Examples of main equipment used for failure analysis
Purpose
Observation
Electrical
characteristic
measurement
Elemental
analysis
Equipment
Stereoscopic microscope
Metallographic microscope
Infrared microscope
Ultrasonic microscope
X-ray fluoroscope
Ultrasonic flaw detection equipment
Liquid crystal analysis equipment
Emission microscopic analysis equipment
Photographic projection equipment
Scanning electron microscope (SEM)
Transmission electron microscope (TEM)
OBIC/OBIRCH equipment
Curve tracer
Transistor tester/IC tester
LSI tester/memory tester
EB tester
Oscilloscope
Pulse oscillator
Ammeter/voltmeter
Noise meter
Laser tester
CV meter
LCR meter
Manipulator
SR tester
Electron probe micro analyzer (EPMA)
X-ray fluorescence spectrometer
Auger electron spectroscopy (AES)
Ion micro analyzer (IMA)
Electron beam diffraction analyzer
X-ray diffraction analyzer
Electron spectroscopy analyzer (ESCA)
Infrared absorption spectrometer
Emission spectrophotometer
Atomic absorption spectrometer
Ion chromatography equipment
Gas chromatography equipment
Mass spectrometer
Sample
preparation
Cutting machine/Grinding equipment
Sample packing device
Package unsealing equipment
Plasma etcher
Deposition equipment
Draft (discharge air/wastewater)
Etching liquid
Clean bench
Ultrasonic disc cutter
Laser cutter
FIB
Thickness/shape
measurement
NanoSpec (trade name)
Ellipsometer
Talystep (trade name)
Tunneling microscope
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Failure Analysis of Semiconductor Devices
4.2.1
Confirmation of information on failure
When obtaining the device to be analyzed and to analyze the failure, it is necessary to confirm the following
items.
Product class name, manufacturer name, product specification, serial number (manufacturing time)
Delivery time, contents of receiving inspection, implementation time
Implemented device, implementation condition, circuit, device position in the circuit
Failure occurrence status (use environment, use conditions, period of use, failure occurrence time)
Failure mode (any of complete failure, gradual failure and intermittent failure; electric characteristic,
failure rate)
Route and period from failure occurrence to obtainment of failed products
By studying the above information well, the contents of failure and the failure mechanism can be estimated
to some extent and concrete procedures of later failure analyses can be determined.
The number of the failed devices is usually small and there are many cases with only one. Mistakes in
analysis procedures may lead to not only the destruction of samples but also an unknown cause of failure.
Before starting failure analyses, it is vital to gather and confirm information well. During analyses, it is
important to prepare non-defective products and carry on the analysis while comparing with them.
4.2.2
External observation
The failure analysis begins with observing the failed devices well and confirming the failure mode.
Stereoscopic microscopes (with 5 to 100 times power) are the most suitable for the external observation. Pay
attention to the appearance of encapsulation resin (discoloration, attachment of foreign substances, crack)
and the appearance of leads (plating, soldering, migration, whisker, fracture). If necessary, observe with
higher-power optical microscopes or scanning electron microscopes. If there is a foreign substance, identify
the element using the surface micro-analyzer described later. If the existence of a crack is suspected, detect the
position and the size using ultrasonic flaw detection equipment (SAT analysis).
4.2.3
Confirmation of characteristic analysis/failure mode
After the external observation, confirm the failure mode. Check the operating conditions of circuits using
curve tracers, oscilloscopes or LSI testers or the like, and compare them with the characteristics of product
specifications and non-defective products. If the failure does not reappear, measure at high temperature or
after vibration tests. If the failure is not found, it may not be caused by the device itself, so it is necessary to
study the occurrence status again.
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4.2.4
Failure Analysis of Semiconductor Devices
Nondestructive analysis
a) X-ray fluoroscopy
This is the method to observe the internal state nondestructively without unsealing the package of the device.
As the transmission rate of X-rays differs according to the quality of materials or the thickness, the internal
structure is obtained as a contrast image of the X-ray. Aluminum (Al), silicon (Si) and the like with light
atomic weight have a high transmission rate and are difficult to identify, but gold (Au), cupper (Cu), iron (Fe),
solder (Sn, Bi, Ag, Pd) and the like have a low transmission rate, so the state can be identified easily. The state
of bonding wires (wire breakage, short-circuit, wire flow), the state of die bond (spread/void), voids and the
like in the encapsulation resin can be confirmed (Figure 4.2 and Figure 4.3). Recently there is equipment
with small X-ray focus (1 μm to 10 μm) and it is applied to the analysis of compact packages such as CSP (chip
size package) or TCP (tape carrier package).
Au bump
Places short-circuited
by the attachment of
foreign
Figure 4.2
Case example of
X-ray analysis of wire flow
Figure 4.3
Case example of X-ray analysis of
short-circuit between CSP bumps
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4
Failure Analysis of Semiconductor Devices
b) Ultrasonic flaw detection analysis (SAT analysis)
Formerly, when analyzing the interfacial delamination between a package crack or Si chip or a die pad (lead
frame) and encapsulation resin, the method of cutting the package and grinding the cross section (destructive
analysis) was employed.
There are some problems in this method, such as inefficiency (working hours, number of processed
pieces), difficulty in positioning analysis places and the occurrence of troubles (delamination, crack). These
arise from the analysis being made by destroying the package.
On the other hand, SAT (scanning acoustic tomograph) is a method of analyzing using ultrasonic waves
without destroying the package.
The ultrasonic wave transmitting medium is partially reflected and partially transmissive if there is any
interface with a different medium (Snell’s law). If ultrasonic waves are projected from the surface of the package,
the ultrasonic waves transmit resin, reach the surface of Si chip and at the interface reflected waves and
transparent waves are generated (Figure 4.4).
Therefore, the defects and the structure inside the package can be analyzed two-dimensionally by receiving
the reflected waves moving (scanning) a lens tube (transducer) discharging ultrasonic waves and by performing
image processing (tone indication) of the characteristics (mainly the intensity of reflected wave) (Figure 4.5).
For example, if the delamination is generated at the interface between the resin and the silicon chip, almost
all the incident ultrasonic waves in the delamination (air layer) are reflected, so the reflected waves with high
intensity are received and the delamination can be detected. As the delamination and cracks generated in the
package are in a minute air layer, they can be also detected.
However, if the package surface is uneven, a black shadow may appear in a marking part as the ultrasonic
waves reflect diffusely on the uneven part.
SAT analyses are positioned as an analysis technology essential for semiconductor packages which will
become more and more important, including the reduction of the lead time for development, evaluation cost
reduction, analysis accuracy improvement, etc.
Ultrasonic pulse
(Transmitting wave)
(Receiving wave)
Place where a black shadow
appears due to marking
Water
Inner lead
Reflected wave
Chip
Resin
Chip
Delamination
places
Die pad
Figure 4.4
Ultrasonic exploration
principle
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Figure 4.5
Case example of analysis (delamination
on a white part at the corner of the chip surface)
4
4.2.5
Failure Analysis of Semiconductor Devices
Unsealing
The purpose of unsealing is to expose the surface of the chip without damaging the surface of the silicon
chip, the wire and the lead frame and to make the later observation and measurement, but it is unexpectedly
difficult to unseal in a non-skilled method and firmly. During unsealing, it is important to select the method
in view of the types and the materials of packages. In case of ceramic encapsulation devices, the cover is
unsealed with a mechanical technique. Currently, mainstream plastic encapsulation devices are unsealed using
the following:
a) Encapsulation resin dissolution by chemicals
b) Encapsulation resin ashing by a plasma reactor
c) Mechanical unsealing
In addition, recently new types of packages such as CSP (chip size package) or TCP (tape carrier package)
are used, and various unsealing methods suitable for them are reported4.1).
a) Encapsulation resin dissolution by chemicals
Fuming nitric acid (70°C to 80°C) and sulfuric acid (200°C to 250°C) are used to dissolve epoxy group resin.
The URESOLVE (trade name) and the like are used to dissolve silicon group resin.
Though dissolution by chemicals can be done easily, it has the disadvantages that it requires much skill and
that the foreign substances on the surface of chips might be removed at the same time. In practical application,
samples useful for the later observation and measurement can be obtained if the wire and the lead are kept as
they are when the resin on the chip has been partially removed with a drill and dissolved until the whole
surface of the chip is exposed.
Unsealing using chemicals must be conducted in a draft as it is harmful and dangerous to human bodies.
Also, the waste disposal must be done in compliance with the law.
b) Encapsulation resin ashing by a plasma reactor
In this method, oxygen (O2) gas in a plasma state is reacted with encapsulation resin and removed. The
drawback of this method is that it takes a long time to process samples as the reaction rate is slow (approx.
50 μm/h), but its use has been gradually generalized as the state of the surface of the chip is well kept.
c) Mechanical unsealing
In this method, unsealing is conducted by cutting the resin with a mechanical force using metal scissors,
pincers, nippers, files, etc. The surface of the chip is exposed relatively easily by breaking the device when
it is taken out and put into a solder bath and thermal stress is applied to it. Though this method can be
conducted most easily, the drawback is the lack of certainty.
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Failure Analysis of Semiconductor Devices
4.2.6
Internal observation and measurement
The device, with the surface of the chip exposed by unsealing, is observed with a stereoscopic microscope
and then with an optical microscope. With the stereoscopic microscope, the state of chips (cracks, the
attachment of foreign substances), the state of die bonds, the state of wires and the state of leads are observed
carefully. It is important to change the lighting conditions by tilting the device in various directions. Then the
surface of the chip is observed with the optical microscope. Optical microscopes are essential to the observation
of the surface of chips as they have 1500 times power. As the surfaces of the chips differ in the thickness of
oxide films, etc., they are colored by interference. As the interference color depends on the film thickness,
abnormalities of the film thickness can be detected by comparing with non-defective products. The
abnormalities detected by internal observations are as follows:
Attachment of foreign substances
Pattern abnormalities
Abnormalities of the film thickness
Wire breakage, short-circuit
Corrosion of Al wire
Al migration
Cracks on passivation films
a) Optical microscopic observation
As optical microscopes have been used for a long time and there are a variety of different types, it is important
to select and use those most suitable, according to their features. Table 4.2 shows the types and the features
of optical microscopes.
Table 4.2
Types and features of optical microscopes often used for failure analysis
Types and attached
Magnifying
power
functions of microscope
Stereoscopic
microscope
x0.7
to
x160
Abnormalities on the surface can be detected by
projecting light at a sharp angle to the surface of
samples.
Dark field
Polarization system
Infrared system
T04007BE-4 2009.4 4-8
Used for macro observations such as low power, long
operating distance, wide field, three-dimensional
observation and packages
Microscopes used for the most varied purposes in the
field of microelectronics. Usually used in the bright field
and incidence. The following functions are included.
Metallographic
microscope
Differential
interference
Features/applications
x25
to
x1500
Create a color coordinating the difference between the
unevenness on the surface of samples by using a prism
and polarized light.
Abnormalities and defects on the surface can be detected
coordinately by using two rotating polarized light filters.
Observe the bonding condition between the silicon ship
and the die pad utilizing a high transmission property of
infrared ray for silicon.
4
Failure Analysis of Semiconductor Devices
Metallographic microscopes are the most widely used in the field of semiconductors for observation by
projecting light on the sample and magnifying the light reflected from the surface of the sample with a lens.
With dark-field microscopes, the unevenness on the surface is emphasized by projecting light diagonally on
the sample. In differential interference, the unevenness of the sample appears colored for emphasis. Polarization
systems are effective for observing the structure of transparent samples by using polarized light and are used
for observing in liquid crystal analysis to detect the position of leaks on chips. In infrared systems, the state
of die bonds under the silicon chips can be observed by using a high transmission property of infrared ray for
silicon.
b) SEM observation
SEMs (scanning electron microscopes) as well as optical microscopes are widely used for failure analyses.
With SEMs, the surface of the sample is observed by projecting electron beams on the sample and detecting
the secondary electron emitted from the sample, and the sample can be magnified from a few times to 100,000
times. As SEMs have a large focus depth and it is easy to obtain the observations of stereoscopic shapes, they
are used not only for failure analyses but also for acceptance inspections of materials or parts and for quality
control in the manufacturing process. Figure 4.6 shows observation example of the surface of the chip by SEM.
Figure 4.6
Case example of observation of SEM
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4
Failure Analysis of Semiconductor Devices
With SEMs, not only is the shape of the surface of the sample observed using the secondary electron,
but a wide variety of information can also be obtained by adding various kinds of observation equipment.
VC (voltage contrast) method
In this method, voltage is applied to the sample electrode and the distribution of potentials on the
surface of the chip is obtained. Though the materials of wires are the same, the contrasts differ according
to potentials, so potential maps can be obtained.
EBIC (electron beam induced current) method
This method utilizes the phenomenon that electric current flows when the electron beam is irradiated on
the p-n junction, and it is used for the determination of the position of the p-n junction or the diffusion
depth.
CL (cathode luminescence) method
This method utilizes the phenomenon that the electron excited by electron beams and the positive hole
emit light at the time of recombination, and it is used for the determination of defects inside chips,
precipitation and the length of carrier diffusion.
EPMA (electron probe micro analysis) method
This is the method of elemental analyses using characteristic X-rays emitted from the samples. The
details of this method are described in “4.2.9 Surface microanalysis”.
c) TEM observation
While SEMs are equipment by which electron beams are reflected on the surface of the sample, TEMs
(transmission electron microscopes) to make observations by transmitting electron rays are also effective.
TEMs have a resolution of approx. 0.1 nm to 0.2 nm and it is possible to magnify to the atomic level. So, they
are used to observe tiny precipitate and lattice defects in chips, but it is rather difficult to prepare the samples
because the sample thickness must be reduced to approx. 0.1 μm.
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4
4.2.7
Failure Analysis of Semiconductor Devices
Search for failure locations
Recent semiconductor devices may not be able to identify failure locations only by internal observations
because of the advanced miniaturization and high integration. To identify the failure locations is the most
important analysis to determine the failure mechanism. EB tester analysis, liquid crystal analysis or emission
microscope analysis, and wiring-part defect analysis using OBIRCH equipment are some of the methods to
search the failure locations, and each of them is effective. Each method is described below.
a) EB tester analysis
EB tester analysis is the method for detecting the operating waveform and the potential contrast image of
a device without contact by operating the semiconductor device with an LSI tester in SEM. An example of EB
tester analysis is shown in Figure 4.7.
Figure 4.7
Case example of EB tester analysis (wire breakage)
b) CAD navigation
This is a method to make identifying the region in large integrated circuits infinitely easier by linking design
layout data (electronic file) and the positional information of analysis equipment such as an EB tester.
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4
Failure Analysis of Semiconductor Devices
c) Liquid crystal analysis method
In case of leak current trouble in the device, the place of leak occurrence generates heat, so the temperature
of the place rises. A certain type of liquid crystal causes phase transition at near ordinary temperatures, and
becomes the transmission state of polarized light due to ups and downs of the transition point, so by using
this, the places of leak occurrence can be identified. Figure 4.8 shows a case example of liquid crystal analysis
methods.
Figure 4.8
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Case example of liquid crystal analysis4.2)
4
Failure Analysis of Semiconductor Devices
d) Emission microscopic analysis
Emission microscopes are equipment for detecting luminous phenomena occurring when voltage is applied
to the device. In case of leak current trouble in the device, the electric field is concentrated on the failure
locations and hot carrier is generated. Then the weak light emitted during recombination is detected by highly
sensitive detectors and observed as a luminescence image, and the luminous places (failure locations) are
identified. Figure 4.9 shows the case example.
Recently multilayer wiring structures have become the mainstream, with the high integration of semiconductor
devices. So, the luminous phenomena may not be detected from the surface of chips. Then, these days, the
luminous places may sometimes be identified by processing the device and using the emission microscope
from the back surface of chips. Figure 4.10 shows the case example.
Figure 4.9
Case example of emission
microscope analysis
Figure 4.10
Case example of emission
microscope analysis from back surface
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Failure Analysis of Semiconductor Devices
e) Wiring-part defect analysis using OBIRCH equipment
OBIRCH (optical beam induced resistance change) methods are the methods for detecting the change in the
current due to the temperature rise of wiring caused by laser beam irradiation on Al wiring4.3). The temperature
rise at the moment the laser is irradiated on the point with defects such as voids at the wiring part is bigger
than that during irradiation on the points without defects. Consequently, the resistance increase in defective
parts becomes large and the current decrease becomes large, too. This current change is detected by a highly
sensitive detector and the defective parts are identified. Figure 4.11 shows the case example.
Failure point
(a) Failure identified by OBIRCH
Figure 4.11
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(b) Cross section observation of failure part by SIM
Case example of analysis in OBIRCH method4.4)
4
4.2.8
Failure Analysis of Semiconductor Devices
Processing technology for analyses
a) Etching
In order to carry on analyses, it is necessary to remove a part of the sample device by dissolution. Table
4.3 shows the etching liquid usually used. During etching, it is necessary to select an etching liquid that does
not dissolve other substances but dissolves only the intended substances. For the measurement of film
thickness, there are optical methods such as ellipsometers, NanoSpec (trade name) and mechanical methods
using contact needles such as Talystep (trade name).
Table 4.3
Etching liquid usually used
Substance
Etching liquid composition
SiO2
28ml : HF
170ml : H2O
113g : NH3
100 to
250nm/min
PSG
Same as above
550nm/min
HF
Si3N4
Remarks
100nm/min
CVD at 800°C
H3PO4
10nm/min
180°C
Polysilicon
1ml : HF
26ml : HNO2
33ml : CH3COOH
150nm/min
Al
1ml : HCl
2ml : H2O
Au
4g : KI
1g : I2
40ml : H2O
0.5μm/min to
1μm/min
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4
Failure Analysis of Semiconductor Devices
b) Cross-section grinding
In case of observing the cross section of the sample (cross section of chip, cross section of lead frame, cross
section of encapsulation resin), observe by embedding the sample in the resin and exposing the intended cross
section by grinding. In this case, it may be necessary to cut or form the sample to be suitable for embedding.
In each case, process in such a way that mechanical stress is not applied, and so that there is no alteration of
samples due to temperature rise. When selecting embedding resin, resin with the best adhesion to samples
must be selected. When grinding, change sanding sheets successively from those with large particle size to
those with small particle size, but be careful not to leave scars due to grinding on the sample. Figure 4.12 shows
a photograph of the cross section of the chip.
Figure 4.12
Cross section of chips by cross-section grinding
c) FIB processing
In order to observe the cross section of arbitrary places of miniaturized semiconductor devices, FIB (focused
ion beam) equipment with alternative etching functions and SIM functions exercise its power these days. In
FIB equipment, micro alternative etching can be realized by narrowing down a gallium ion (Ga+) beam to
approx. 0.1 μmm and irradiating it to the sample. The usage of this equipment enables cross-sectional observation
to advance dramatically. Figure 4.13 shows a photograph of the cross section processed by FIB equipment.
Cu
Low- k
N iS i
55nm
S TI
Figure 4.13
T04007BE-4 2009.4 4-16
Cross-section view of chip by FIB processing4.5)
4
4.2.9
Failure Analysis of Semiconductor Devices
Surface microanalysis
In analyzing failures, there may be some cases that require elemental analyses of trace substances. Recently,
surface microanalysis of solid substances has been developed significantly and samples of 1 μm3 can be analyzed
at a sensitivity of 100 ppm.
The principle of surface analysis is to identify elements by projecting electrons, ions, light, X-rays, etc. on
the sample and detecting electrons, ions, light, X-rays, etc. emitted from the sample. Table 4.4 shows a
synopsis of surface microanalysis technology.
a) EPMA (XMA) (electron probe micro analysis)
EPMAs are in the most widespread use for analysis, usually equipped with SEMs. Making observation with
SEM, the identification of elements on the spot and the measurements of the element distribution on the
surface of the sample can be made. In EPMAs, as specific characteristic X-rays are generated in the sample
elements in case of the incidence of electron rays on the sample, the elements are identified by dispersing
characteristic X-rays. Also, the abundance can be determined from X-ray intensity. There are WDX (wavelength
dispersion method) and EDX (energy dispersion method) detection methods of X-rays. Each method has its
positive features and both are widely used. Figure 4.14 shows measurement examples of the element
distribution of foreign substances by EPMA.
(a) SEM image in the wiring part
Figure 4.14
(b) Measurement example of Al element in EPMA
Example of EPMA analysis of foreign substance in chip
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4
Failure Analysis of Semiconductor Devices
b) SIMS (secondary ion mass spectrometry)
In SIMS, argon (Ar), oxygen (O), etc. are irradiated on the sample and the elements are identified by mass
analysis of ions emitted from the sample by sputtering. There are many types of SIMS, using various
irradiation systems and detection systems, but the method that analyzes surfaces using fine ion beams is
called I(M)MA. I(M)MA can analyze all the elements. As its detection limit is approx. 1 ppm and it is highly
sensitive, it is used for the identification of foreign substances, the measurement of diffusion profile, etc.
c) AES (Auger electron spectroscopy)
In AES, elements are analyzed by incidence of low accelerated electrons and by dispersing Auger electrons
generated from the sample. As the depth resolution of this method is as shallow as 1 to 2 nm, it is very
effective for measuring the composition of 2 or 3 atomic layers on the surface of the sample. This method can
analyze all the elements except hydrogen (H) and helium (He). The sensitivity differs according to the
element, but it is approximately 0.1% of the atomic layer. It can measure the profiles of the depth directions
of foreign substances and thin films in conjunction with sputtering devices.
d) ESCA (XPS) (electron spectroscopy for chemical analysis)
ESCAs disperse photoectrons emitted from the sample by incidence of X-rays or ultraviolet rays to the
sample. As not only the identification of elements but also the chemical-bonding state can be seen, this
method can analyze the interface between semiconductors and insulating films.
e) XRFS (X-ray fluorescence spectroscopy)
XRFSs identify elements by incidence of X-rays to the sample and by dispersing X-rays emitted from the
sample. XRFSs are used for analyzing foreign substances, and for quantitative analyses of phosphorous (P)
of passivation films, etc.
These surface microanalysis technologies serve as very powerful tools for failure analyses because they
can make elemental analyses of micro regions of μm order at the sensitivity of approx. ppm. The handling of
the equipment and the interpretation of the results require high technology and experience.
T04007BE-4 2009.4 4-18
Electron Paramagnetic
Resonance
Electron Spectroscopy
for Chemical Analysis
Electron Spin
Resonance
ESCA
ESR
Electromagnetic
wave
(to 10 MHz)
Electromagnetic
wave
(to 10 MHz)
Characteristic
X-ray
Electron
(Some to 50 keV)
Electron Probe Micro
Analysis
EPMA
EPR
Light
Current
Electroluminescence
EL
(Radius) >0.5 μm
(Thickness) 0.3 μm to some μm
(Energy, substance
dependence)
Composition analysis on wafer
and device (ultrathin film, not
applicable), contamination,
detection of attachment
Elemental composition analysis
(above Na with EDX, above
boron (B) with WDX)
Dispersion by EDX or WDX of
characteristic X-rays generated
by electron beam irradiation
Measurement of resonant
absorption spectrum by transition
Electromagnetic between Zeeman levels generated
wave
placing electron spin in the
magnetic external field
Generic designation of XPS and
UPS
Identification of impurity ion,
defective structure, electron spin
relaxation, electron spin
interaction
PL law is used in case of
special analysis.
Degradation analysis of lightemitting device, defects in
process introduction, impurity
evaluation
Energy level and relative
concentration centering band
gap, emission recombination
Spectroanalysis of the light
emitted during recombination of
a few carriers forward bias is
applied to and injected to
Identification of defects by
hydrogen (H), etc. in α-Si
Utilization of SOR
(synchrotron orbital radiation)
is expected.
Position of impurity in
semiconductor bulk crystal,
defective structure
(Radius) >10 nm
(in case of using STEM)
(Thickness) 0.3 μm to some μm
(Energy, substance dependence)
Utilization as a means of
EPMA
Elemental composition analysis
through the energy distribution
of X-ray intensity (sensitivity of
0.1% and more)
Pulse-height analysis of
irradiated X-ray energy (pulseheight) by semiconductor
detectors (SSD) such as Si (Li)
(Radius) 1 μm to some μm
(Thickness) Some μm
Existence of dislocation penetrating
p-n junction, analysis of degradation
of light-emitting device,
measurement of diffusion length
Distribution of electromotive force
Existence centering carrier
effects of metal-semiconductor by
recombination such as crystal
electron-hole of electron beam
defects near junctions
excitation, or both ends of p-n junction
(Radius) >0.5 μm
(Thickness) to 1μm
Defects in semiconductors,
precipitates, impurity
segregation, measurement of
carrier diffusion length
Light emission by recombination Nonradiative state in the
of electron-hole of electron beam unexcited part or the quick
recombination part
excitation
ESR in case of paramagnetic
Electromagnetic samples
wave
Electron
X-ray
(Some to 30 keV)
Energy Dispersive
X-ray Spectroscopy
EDX
Current
Photon
Electron
(Some to some
dozens of keV)
Electron
(10 keV to 40 keV)
Cathodeluminescence
CL
(Radius) 0. some nm
Micro region TED (to 20 nm)
Micro region EDX (to 10 nm)
Micro region SACP (to 3 nm)
Able to collect complementary
data with various attachments as
well as STEM functions
STEM+EDX(+ELS) (+DLTS)
(+SACP selection field
channeling pattern)
Electron
(transmission/
diffraction)
Electron
(100 keV to
200 keV)
(Radius) 0.1 mm to 1 mm
(Thickness) 1 nm to 2 nm
Surface oxidation, contamination,
impurity analysis, depth direction
elemental analysis, composition
analysis of layer such as
intermediate reaction
Able to analyze the surface
element (above Li) and depth in
conjunction with ion guns
Energy dispersion of Auger
electron (by CMA, etc.), record
Auger electron of differential curves.
Resolution
Application
Principle or Method
Source: OYO BUTURI, Vol. 51, p. 827 (1982)
Summary of surface microanalysis technologies
Obtainable Information
Detection
Electron Beam
Induced Current
Analytical Electron
Microscopy
AEM
Electron
(0.1 keV to 5 keV)
Input
EBIC
Auger Electron
Spectroscopy
Name
AES
Abbreviation
Table 4.4
4
Failure Analysis of Semiconductor Devices
T04007BE-4 2009.4 4-19
T04007BE-4 2009.4 4-20
Ionized atom
Electrical field
(to some dozens
of keV)
Electron
(diffraction)
Electron
Electron
(15 keV to 500 keV)
Electron
(≤ some hundreds
of eV)
Electromagnetic
wave
Low Energy Electron
Diffraction
Low Energy Electron
Loss Spectroscopy
Nuclear Magnetic
Resonance
LEED
LEELS
NMR
Surface crystal structure,
absorption state, surface atom
rearrangement, etc.
(superperiodic lattice structure)
Nuclear internal field,
identification of nuclide from
nuclear spin relaxation, atomic
arrangement of substances
Incidence of low-speed electron
Surface electronic state of single
beam on the surface of the sample,
crystal (band structure)
measurement of energy distribution
of reflection electron by applying AC
to electron gun accelerating voltage
Vertical incidence of low-speed
electron beam on the surface of
the sample, image formation of
reflective diffraction pattern on
hemisphere fluorescent screen
Analysis of hydrogen (H) and
fluorine (F) in α-silicon
Electronic structure of
semiconductor clean surface,
impurity absorption surface
structure
Thin film crystal structure,
semiconductor surface
absorption layer
Identification of substances from Measurement of concentration
of oxygen (O) and carbon (C)
absorption band peculiar to
molecule or analysis of molecule in silicon
structure
Change the number of frequency
(wavelength) of infrared rays and
irradiate, measure the absorption
spectrum by molecular vibration.
Composition analysis of
multilayer epitaxial layer,
impurity diffusion, residual
impurity analysis
One-dimensional elemental
composition analysis, depth
direction composition analysis
(composition sensitivity ppb to ppm,
larger dependence on elements)
Sputter-ionize surface substances
with primary ion, analyze with
mass analyzer, micro beam
scanning method and image
conversion method.
Same as RBS
TEM image of thick sample
High voltage TEM
Dynamic observation of
dislocation
Si atomic structure (superlattice (Radius) 0. some nm to
some nm
structure, etc.), atomic structure
(Thickness) Monoatomic layer
of compound semiconductor
Record of ionization energy
distribution on the surface of
high electrical field as a figure
Field evaporation ion at the end
of needle-like metal or surface
field distribution is converted to
ionization rate such as rare gas.
(Thickness) Some atomic
layer
(Wave number) > 0.1 cm-1
(Radius) 1 μm to 2 μm,
surface ionization type ion:
0.1 μm
(Thickness) Some nm to
10 nm
(Radius) Some nm
(Radius) Some nm
(Thickness) Monoatomic layer
Semiconductor structure,
surface diffusion, analysis of
depth of field penetration
Record of emission probability
on the surface of high electrical
field as a figure, surface atomic
structure, atom motion
Resolution
High electrical field is formed at
the end of needle-like metal,
energy more than work function
is obtained and atom is radiated
to outside of vacuum.
Application
Obtainable Information
Principle or Method
Measurement of resonant
absorption spectrum by transition
Electromagnetic between Zeeman levels generated
wave
by placing nuclear spin in the
magnetic external field
Photon
(transmission)
Photon
(Infrared rays
2.5 μm to 16 μm)
Infrared Absorption
Spectroscopy
Secondary ion
Ion Microprobe (Mass) Ion (Ar, O, Cs, etc.)
(Some keV to
Analysis
30 keV)
Ion Back Scattering
IR
IMMA
IBS
Neutral atom
Electrical field
(to some dozens
of keV)
Electron
(transmission/
diffraction)
Detection
Input
Electron
High Voltage Electron
(0.5 MeV and more)
Microscopy
Field Ion Microscopy
FIM
HVEM
Field Emission
Microscopy
Name
FEM
Abbreviation
4
Failure Analysis of Semiconductor Devices
SIMS
Electron
(Some dozens to
200 keV)
Secondary Ion Mass
Spectrometry
Scanning Transmission
Electron Microscopy
Ion (Ar, O)
(Some hundreds of
eV to 10 keV)
Scanning Ion
Microscopy
SIM
STEM
Ga+ ion
(5 keV to 30 keV)
Scanning Electron
Microscopy
SEM
Voltage
Secondary
electron
Electron
(5 keV to 50 keV)
Scanning Auger
Electron
Spectroscopy
SAES
Spreading Resistance
Secondary
electron
Reflection
electron
Electron
(3 keV to 20 keV)
Scanning Auger
Microscopy
SAM
SR
Scattered ion
H+, He+ ion
(Some hundreds of
eV to some MeV)
Rutherford Back
Scattering
RBS
Electron
TEM including the mechanism
(transmission/ able to scan primary irradiation
diffraction)
beam
Secondary electron
Current
SEM mode image by secondary
electron applicable, most able to
add EELS, etc.
Usable as AEM
Resistivity measurement of
bulk, epitaxial wafer
Composition analysis of surface (Radius) 100 μm to 500 μm
(Thickness) Monoatomic
monoatomic layer, surface
layer to some atomic layer
absorption, contaminated
impurity analysis, impurity
analysis of ion-implanted layer
(Radius) to 1 nm
(Thickness) Some nm
(Width-Thickness) Some μm
(Radius) >10 nm
Elemental composition analysis
of surface substances (secondary
distribution not applicable), but
higher sensitivity than I(M)MA
Detect the flowing current when
Specific resistance
forward voltage is applied to metal
probe contacted with the surface of
semiconductor, and obtain specific
resistance. Two-probe method
Sputter-ionize surface
substances with primary ion and
Secondary ion analyze with mass analyzer.
Primary ion is not scanned.
Scan micro ion beam and record
the intensity of secondary
electron (SE) in synchronization
with primary beam scanning.
Scan micro electron beam and
record the intensity of secondary
electron (SE) and reflection
electron (BE) in synchronization
with primary beam scanning.
Same as SAM
Surface thin layer shape of
various materials and device
(Depth to 40 nm), grain status.
Local composition analysis of the (Radius) ≥ 50 nm
surface of wafer, device, analysis (Thickness) 0. some nm to
2 nm
of various contamination,
oxidation, reaction layer
Three-dimensional elemental
composition analysis of surface
thin films, rather difficult
analysis of chemical shift
Uneven surface shape, material
difference, grain size or
direction difference.
(Radius) 5 nm to 20 nm
(The heavier element,
the smaller)
Wafer surface rearrangement,
atomic site of impurity
diffusion, structural analysis of
thin films (SiO2/Si, etc.)
Rearrangement of surface
construction atoms, interstitial
site of impurity atom using
channeling phenomena,
existence of defects
Backward anelasticity
(Rutherford), estimation of
energy dispersion and quantity
of scattered ion
(Radius) > 3 nm
Various materials, surface
shapes of devices, length
measurement standards, etc. can
be recorded simultaneously.
(Radius) Some μm
The depth depends on
optical-absorption length.
Evaluation of crystal growth,
analysis of defects in process
introduction such as ion
implantation, identification of
impurities
Energy level and relative
concentration centering band
gap and emission recombination
Spectroanalysis of the light
emitted during recombination of
electrons excited by irradiation
of light such as laser
Uneven surface shape,
qualitative composition analysis
Resolution
Application
Obtainable Information
Principle or Method
AES scanning micro electron
Auger electron beam (SEM type: ≤ 20 nm,
CMA type: to 100 nm)
Light
Light
Photoluminescence
Detection
PL
Input
Name
Abbreviation
4
Failure Analysis of Semiconductor Devices
T04007BE-4 2009.4 4-21
Detection
Secondary
electron
Input
Electron
(Some keV to
30 keV)
T04007BE-4 2009.4 4-22
X-ray Microprobe
Analysis
X-ray Photo-emission
Spectroscopy
X-ray Fluorescence
Spectroscopy
X-ray Topography
XPS
XRFS
XRT
XD
XMA
X-ray Diffractometry
WDX
Photoelectron
X-ray
(Some keV to
30 keV)
X-ray
(diffraction)
X-ray, RI
Characteristic
radiation source
X-ray
(10 keV to 100 keV) (fluorescence)
X-ray
(Some keV to
10 keV)
X-ray
(diffraction)
X-ray
(diffraction)
X-ray
(Some to some
dozens of keV)
Wavelength Dispersive
X-ray Spectroscopy
UPS
X-ray
Photoelectron
Photon
(Ultraviolet ray,
4 eV to 40 eV)
Ultraviolet
Photo-emission
Spectroscopy
Electron
Electron
Transmission Electron
(transmission/
(30 keV to 200 keV)
Microscopy
diffraction)
Stroboscopic SEM
StroboSEM
TEM
Name
Abbreviation
Obtainable Information
Application
Crystal structure analysis, detection Crystallinity, defect (twin
of directions, photographic
crystal, etc.) evaluation
method, chart method (single
crystal, powder, etc.)
Record diffraction X-ray pattern
or intensity by Bragg reflection
on crystal lattice surface.
(Radius) to 5 μm
(Thickness) to 10 μm
(Section topograph)
Defect distribution in wafers
(bulk, device process, distorted
distribution, etc.)
Parallel scanning of dispersion
X-ray beam together with the
sample, record of diffraction image
corresponding to single crystal
Crystal defect (dislocation),
precipitates, imaging of impurity
concentration stripe on
photograph or TV screen
(Thickness) 0.1 μm to
some μm
Analysis of surface attached
substances
Elemental composition, band
(Thickness) 1 nm to some nm
structure of crystal, measurement
of bonding state, analysis of
interface between semiconductor
and insulating film
(Thickness) 0.1 to some
dozens of μm
Spectroanalysis by EDX or WDX Elemental composition analysis
of secondary (fluorescent) X-ray (above N), difficult for below Ni
in two-crystal method
Energy dispersion of X-ray
(usually AlK ray, Mgk ray, etc.)
excited photoelectron (core
electron)
With the shift of atomic orbital
energy in chemical-bonding
state, detect chemical shift
especially in light elements.
Used as a means of EPMA
Elemental composition analysis
through wavelength distribution
of X-ray intensity (sensitivity:
0.01% and more)
Disperse wavelength of
irradiation X-ray by Bragg
reflection by dispersive crystal
and measure the intensity by
photoelectric conversion.
Same as EPMA
(Thickness) Monoatomic layer
Surface treatment state,
interaction of transition metal
and absorbed electron,
interfacial reaction layer
structure
Elemental composition analysis
of surface substances, electronic
surface level, estimation of
dissociation or non-dissociation,
chemical-bonding state
Energy dispersion of
photoelectron (valence electron,
conduction electron) of
ultraviolet excited wavelength,
measurement of electronic
energy of shallow levels
(Radius) Some μm
(Thickness) 0.3 μm to
some μm
(Energy, substance
dependence)
(Radius) to 0. some nm
(Thickness) to 5 nm
(Stereographic image)
Crystal defects in
semiconductor materials
(dislocation, precipitates, etc.),
crystal structure analysis
Crystal cross-section shape,
crystal structure analysis by
diffraction, existence of defects,
etc.
(Radius) > 3 nm
Resolution
Diffraction by primary thermal
electron or field-emission
electron, or record of transmission
magnified image, also called CEM
Using the dependence of emitted Carrier flow in electronic circuit, Potential change in the unit of
etc., potential change, signal
ps in IC circuit, operating
secondary electron dose on
propagation rate, etc.
analysis
surface potential of substances,
measure potential distribution by
phase synchronization with
pulsed irradiation beam.
Principle or Method
4
Failure Analysis of Semiconductor Devices
4
Failure Analysis of Semiconductor Devices
Reference documents:
4.1) Matsushita, Matsushima, and Wada, “Basic Reliability of CSP and Consideration of Failure
Analysis Technique”, The 26th Union of Japanese Scientists and Engineers, pp. 99-104 (1996).
4.2) Kataoka and Wada, “Higher Accuracy of Liquid Crystal Analysis Technique”, The 26th Union of
Japanese Scientists and Engineers, pp. 113-118 (1995).
4.3) Nikawa and Inoue, “Failure Analysis Technique of LSI Using Laser Beam Radiation”, The 25th
Union of Japanese Scientists and Engineers, pp. 29-36 (1995).
4.4) Nakano and Wada, “Al Void Growth in W Via Hole by Stress Migration”, The 44th Japan Society
of Applied Physics, 29a-pc-20 p. 758 (1997).
4.5) Fujii et al., “65 nm Process Technology”, Matsushita Technical Journal Vol. 52, No. 1, p. 13 (2006).
T04007BE-4 2009.4 4-23