18 Fault Isolation and Failure Analysis of 3D Packaging
603
Table 18.5 Pros and Cons of material analysis techniques for 3D packages (Adapted from Refs.
[51–53, 55, 56])
Material analysis
technique
Material
information
provided
Spatial
resolution a
Pros
Cons
EDX
Elemental
analysis
SEM-EDX:
~2 μm
TEM-EDX:
~1–10 nm
Combined with
electron
microscopy
Less sensitive for
light elements
FTIR
IR spectral
fingerprints
~2 μm
Good for organic
materials
Sample prep
challenge, not for
sub micron
AFM-IR
IR spectral
fingerprints
nm
Good for organic
materials
Sample prep
challenge, Lack of
library
XPS
Elemental and
chemical state
information;
Depth profile
5–30 μm
Analysis depth
less than 2–5 nm;
Quantitative
results
Hydrogen and
helium not
detectable
TOF-SIMS
Elemental and
chemical state
information;
Depth profile
~100 nm
Analysis depth
less than 2–5 nm;
All results are
detectable
Semi-quantitative
EBSD
Crystallographic
orientation
10 nm
Visualization of
phases, grain size
and distribution
Sample
preparation take
time
a Rough estimation in optimized condition, actual resolution depends on different equipment and
set up
18.4.2.1 Energy-Dispersive X-Ray Spectroscopy (EDX)
Energy Dispersive X-Ray Spectroscopy (EDX) is a material analysis technique
used in conjunction with electron microscopy, including both Scanning Electron
Microscopy (SEM) and Transmission electron microscopy (TEM), to produce spectra
of X-ray counts versus X-ray energy. When samples are bombarded by the electron
beam, electrons ionize atoms in samples, and generates X-rays with characteristic
energy unique to the ionized atoms. Depending on the energy and reaction volume
with samples of the incident electron beam, elemental composition of the sample
about 1–3 μm in depth could be obtained by SEM-EDX [51]. TEM-EDX provides
higher spatial resolution than SEM-EDX as the reaction volume of the high energy
electron beam is much smaller in the ultra-thin samples. However TEM sample
preparation is time consuming and only a small area could be inspected each time.
With μm range spatial resolution, SEM-EDX could be employed as a non-destructive
material analysis technique to quickly characterize materials on the sample surface.
Figure 18.29 shows an example of how SEM-EDX is employed to find out the
root cause of a die crack. Some foreign materials (FM) shown in Fig. 18.29a is
603
Table 18.5 Pros and Cons of material analysis techniques for 3D packages (Adapted from Refs.
[51–53, 55, 56])
Material analysis
technique
Material
information
provided
Spatial
resolution a
Pros
Cons
EDX
Elemental
analysis
SEM-EDX:
~2 μm
TEM-EDX:
~1–10 nm
Combined with
electron
microscopy
Less sensitive for
light elements
FTIR
IR spectral
fingerprints
~2 μm
Good for organic
materials
Sample prep
challenge, not for
sub micron
AFM-IR
IR spectral
fingerprints
nm
Good for organic
materials
Sample prep
challenge, Lack of
library
XPS
Elemental and
chemical state
information;
Depth profile
5–30 μm
Analysis depth
less than 2–5 nm;
Quantitative
results
Hydrogen and
helium not
detectable
TOF-SIMS
Elemental and
chemical state
information;
Depth profile
~100 nm
Analysis depth
less than 2–5 nm;
All results are
detectable
Semi-quantitative
EBSD
Crystallographic
orientation
10 nm
Visualization of
phases, grain size
and distribution
Sample
preparation take
time
a Rough estimation in optimized condition, actual resolution depends on different equipment and
set up
18.4.2.1 Energy-Dispersive X-Ray Spectroscopy (EDX)
Energy Dispersive X-Ray Spectroscopy (EDX) is a material analysis technique
used in conjunction with electron microscopy, including both Scanning Electron
Microscopy (SEM) and Transmission electron microscopy (TEM), to produce spectra
of X-ray counts versus X-ray energy. When samples are bombarded by the electron
beam, electrons ionize atoms in samples, and generates X-rays with characteristic
energy unique to the ionized atoms. Depending on the energy and reaction volume
with samples of the incident electron beam, elemental composition of the sample
about 1–3 μm in depth could be obtained by SEM-EDX [51]. TEM-EDX provides
higher spatial resolution than SEM-EDX as the reaction volume of the high energy
electron beam is much smaller in the ultra-thin samples. However TEM sample
preparation is time consuming and only a small area could be inspected each time.
With μm range spatial resolution, SEM-EDX could be employed as a non-destructive
material analysis technique to quickly characterize materials on the sample surface.
Figure 18.29 shows an example of how SEM-EDX is employed to find out the
root cause of a die crack. Some foreign materials (FM) shown in Fig. 18.29a is