X-RAY TECHNIQUES FOR 3D METROLOGY AND DIAGNOSTICS...
Transcript of X-RAY TECHNIQUES FOR 3D METROLOGY AND DIAGNOSTICS...
Ehrenfried Zschech | Fraunhofer IKTS Dresden | Germany | [email protected]
Zhiyong Ma | Intel Inc. Hilsboro/OR | USA | [email protected]
X-RAY TECHNIQUES FOR 3D METROLOGY AND DIAGNOSTICS – STATUS AND OUTLOOK
IRSP 2016 | Bad Schandau, 31 May 2016
Picture: NovaledPicture: Fraunhofer IPMS Picture: GLOBALFOUNDRIES
Outline
1. Today‘s and future metrology and diagnostics challenges in microelectronics, Role of X-ray techniques
2. X-ray imaging of 3D structures: From micro to nano
3. Reliability-limiting effects: Imaging of kinetic processes in microelectronic products
4. Outlook:
Hybrid metrology and inspection
Analytical X-ray microscopy with novel X-ray sources
Outline
1. Today‘s and future metrology and diagnostics challenges in microelectronics, Role of X-ray techniques
2. X-ray imaging of 3D structures: From micro to nano
3. Reliability-limiting effects: Imaging of kinetic processes in microelectronic products
4. Outlook:
Hybrid metrology and inspection
Analytical X-ray microscopy with novel X-ray sources
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130nm
90nm
65nm
45nm
32nm
22nm
Beyond CMOS
Functional Diversification: More than Moore
Analog/RF Passives HV PowerSensors
ActuatorsBiochipsFluidics
InformationProcessing
Digital content &System-on-Chip
(SoC)
Interacting with people and environment
Non-digital content & System-in-Package (SiP)
New processes and new materials
Scaling „More Moore“ and Functional Diversification „More than Moore“
From International Technology Roadmap for Semiconductors: http://www.itrs.net
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CM
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ory
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130nm
90nm
65nm
45nm
32nm
22nm
Beyond CMOS
Functional Diversification: More than Moore
Analog/RF Passives HV PowerSensors
ActuatorsBiochipsFluidics
InformationProcessing
Digital content &System-on-Chip
(SoC)
Interacting with people and environment
Non-digital content & System-in-Package (SiP)
New processes and new materials
Scaling „More Moore“ and Functional Diversification„More than Moore“ New Processes and New Materials
Trend: Materials innovations – Increas ingnumber of new materials in microelectronic
products to fulfill performance and reliabilityneeds
for „More Moore“ and for „More than Moore“
From International Technology Roadmap for Semiconductors: http://www.itrs.net
You cannot control what you cannot measure metrology is critical!
Future Products will be Increasingly More Complex
X-ray Techniques for Metrology and Diagnostics
Integral technique covering large areas / many devices metrology
• X-ray diffraction XRD and small angle X-ray scattering SAXS (local
technique at individual structures: TEM (CBED, ENBD, Holography, … +
brightfield imaging)
• X-ray reflectometry XRR (local technique at individual structures: TEM)
• X-ray spectroscopy XRF, XAS (local technique at individual structures:
TEM/EDX+EELS)
High resolution imaging techniques diagnostics/failure analysis
• (micro) X-ray computed tomography micro-XCT
• Transmission X-ray microscopy TXM / nano X-ray computed tomography
nano-XCT
B. Bunday, SPIE Adv Litho 2013
Alain Diebold, ITRS 2011
2 parameters
Gate
Fin
HMHiK/MG
3 parameters
3 parameters
3 p
ara
mete
rs
1 parameter
>10 CD
Parameters
+ Others?
Metrology Gaps for 3D Structures
Destructive technique at individual device (TEM)
vs. nondestructive integral technique (SAXS)
Metrology
driven
demand
Tri-gateMG/HKStrain
TEM Samples
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Materials Science
driven demand
Dimensional Metrology Lab Demand
(driven by 3D transistor)
Automated TEM flow as near-fab metrology solution
CDSAXS is a potential alternative
CD-SAXS: Statements at FCMN 2015 Dresden Conference
R. J. Kline, NIST:
• CD-SAXS is a potential replacement
metrology for visible and UV OCD
• Applicable to periodic test
structures, for 32nm pitch
demonstrated: resolves sub-nm
pitch changes
• Statistical limitations for FinFETs
High-brightness X-ray source
needed!
New X-ray sources are key to success
of CD-SAXS
Flux Plot
CDSAXS
Courtesy of Joe Kline, NIST
Spacer-Assisted Quadruple
Patterning (SAQP)
Pitch/walking
Height
Width
Slope
LER
Shape
3D Metrology Option - CDXAS
SAXS is the technique of
choice for FinFET metrology,
data from reciprocal space
maps
Outline
1. Today‘s and future metrology and diagnostics challenges in microelectronics, Role of X-ray techniques
2. X-ray imaging of 3D structures: From micro to nano
3. Reliability-limiting effects: Imaging of kinetic processes in microelectronic products
4. Outlook:
Hybrid metrology and inspection
Analytical X-ray microscopy with novel X-ray sources
Requirements for XCT in Microelectronics
X-ray source
max energy
for highly x-ray
absorbing
samples
Diverse spectrum of sample sizes, ranging from a few millimeters
to a few inches
A means to compensate for resolution deterioration when using
large sample-to-source distances to avoid sample-source crashing
Efficient data
processing algorithms
and computing systems
for fast time to
tomographic data
No sample trimming should be required!
C4 Bump “Invisible” Defects
Best 2D
X-ray image
could not
detect the
defect!
Physical
x-section
X-ray CT
x-section viewX-ray CT
3D view
Gap ~2um
TPT 10min
X-ray CT
plane view
2D X-ray Imaging vs. 3D XCT
2D X-ray imaging is a matured and widely used analytical method for failure
analysis in microelectronics
- Demonstrated capability for defect detection
- Real time nature
- Availability of automated defect detection routines
Technical challenges for 2D X-ray imaging are:
- Development of smaller / more complex packages
- Small defect dimensions with a lot of interfering features in the FOV
- Increasingly difficult and sometimes impossible to image certain
defects in non-destructive fashion
- Samples often require preparation that may produce artifacts.
This fundamental limitation of 2D X-ray imaging technology is a
common roadblock driving X-ray CT for failure analysis in
microelectronic devices
X-ray Micro Imaging: Principle of Conventional Radiography
SDD
SOD
DF
UFProjection of the (small) specimen on a (large) screen
d > DF : Resolution is limited by size of the source
DF > 0.6 µm (thin target)
Zeiss Versa XCT 520: 0.7 mm resolution
Sub-micron X-ray Tomography for Advanced Packaging: 3D TSV Stacking
Physical Failure Analysis for Advanced Packaging: Micro-XCT of 3D Chip Stack
X-ray computed tomography (XCT): Incomplete Cu TSV filling, variation in
solder flow (AgSn) around the Cu bumps
100 µm
M. Löffler, TU Dresden/DCN, J. Gluch, E. Zschech, Fraunhofer IKTS
M. J. Wolf, Fraunhofer IZM-ASSID
EU project 3D MASTER / BMBF 3D INNOPRO
Xradia Nano-XCT: Lab-based X-ray Microscopy
Multi-chip Stack – High-resolution nano-XCT
Tomography of a partially filled Cu TSV
M. Löffler, TU Dresden/DCN, J. Gluch, E. Zschech, Fraunhofer IKTS
M. J. Wolf, Fraunhofer IZM-ASSID
EU project 3D MASTER / BMBF 3D INNOPRO
Multi-chip stack – High-resolution nano-XCT
Tomography of a AgSn solder bump
M. Löffler, TU Dresden/DCN, J. Gluch, E. Zschech, Fraunhofer IKTS
M. J. Wolf, Fraunhofer IZM-ASSID
EU project 3D MASTER / BMBF 3D INNOPRO
SEM Image of FIB X-section of Copper TSV after nano-XCT Study
1. Nondestructive failure localization: Voids ~ 100 nm size can be localized2. Destructive physical failure analysis: Validation of nano-XCT results
M. Baklanov, P. S. Ho, E. Zschech, “Advanced Interconnects for ULSI Technology”
(Eds.), John Wiley & Sons Chichester, pp. 437 - 502 (2012)
L. W. Kong, E. Zschech, et al., J. Appl. Phys. 110, 053502 (2011) DOI:10.1063/1.3629988
Cavity
Void chain
Curved bottom
Outline
1. Today‘s and future metrology and diagnostics challenges in microelectronics, Role of X-ray techniques
2. X-ray imaging of 3D structures: From micro to nano
3. Reliability-limiting effects: Imaging of kinetic processes in microelectronic products
4. Outlook:
Hybrid metrology and inspection
Analytical X-ray microscopy with novel X-ray sources
G. Schneider et al., APL 81, 2535 (2002)
SEM micrograph X-ray micrograph imaged at 1.8 keV
X-rays
Cu interconnect
Cu via
Wafer
1 mm
In-situ XRM Degradation Experiment @ BESSY Berlin: Electromigration in on-chip Cu Interconnects
A
C
t = 0 h
I = 20 mA
B
D
E F
t = 8:19 h
I = 29 mA
t = 10:44 h
I = 34 mA
t = 10:58 h
I = 30 mA
t = 11:16 h
I = 30 mA
t = 12:41 h
I = 34 mA
void formation
in Cu via
void
X-ray micrographs visualizing void formation, movement and agglomeration inside the passivated vias
G. Schneider et al., APL 81, 2535 (2002)
In-situ XRM Degradation Experiment @ BESSY Berlin: Electromigration in on-chip Cu Interconnects
Mechanical Properties of Thin Film Materials Integrated in Microchips and Advanced Packaging
Chip-package interaction (CPI) is one of the major reliability concerns in leading
edge chips with low-k and/or ultra-low-k insulating material in the on-chip
interconnect stack, because of the low fracture toughness of these materials.
- To prevent chip damage as cracking, e. g. caused by dicing, so-called crack stop
structures are integrated.
- Crack pathways have to be imaged to estimate reliability risks.
Crack propagation and particularly the efficiency of the crack stop structure in an
Intel CORE i3 processor is studied.
SEM images of
cross-section with
crack stop structure
of an Intel CORE i3
processor with 12
metallization layers
Micro Double Cantilever Beam test (MicroDCB)
Scope: crack initiation and propagation
XRM investigation under load
In-situ Mechanical Testing of Multilayer Systems in the X-ray Microscope (XRM)
Force
S. Niese, PhD thesis, BTU Cottbus, 2014
Nano XCT: X-ray Microscope Setup for microDCB Test
dedicated
sample stage
(xyz-Q)
Source Condenser X-ray lens Detection system
1500 mm
Laminography
S. Niese, PhD thesis, BTU Cottbus, 2015 Talk 14: S . Niese
Micro-DCB Test in the nano-XCT Tool at Crack Stop Structures of CORE i3 Processor
Cross section view
Before crack initiation
Crack in front of crack stop
(quick intermediate tomography)
After cracking
Crack up to here
• Delamination occurred typically inside the metallization layer where it was
induced until it reached the crack stop pattern
• The crack changed the direction of propagation at the crack stop structure
Edge of chip
Crack stop region, delaminated/broken structures appear darker
Active chip area
In plane view at metal layer 8
Tomographic image (side view) of
de-lamination between metallization
layers (crack path)
Tomographic image (in plane) showing
the delaminated area (dark) within the
shown metallization layer
Poster 20: K. Kutukova
Outline
1. Today‘s and future metrology and diagnostics challenges in microelectronics, Role of X-ray techniques
2. X-ray imaging of 3D structures: From micro to nano
3. Reliability-limiting effects: Imaging of kinetic processes in microelectronic products
4. Outlook:
Hybrid metrology and inspection
Analytical X-ray microscopy with novel X-ray sources
What does “Smart” Metrology look like?
Multiple vectors need industry/vendor focus
Enhanced (hybrid) in-fab metrology particularly for 3D
structures
Product/layout awareness
Evaluation and development of lab analytical capabilities for
potential in-fab use
Integration of manufacturing-worthy and cost effective near-fab
capabilities
Where required, enable the lab capability for near-fab support
A manufacturing flow that seamlessly incorporates all
of these elements
X-ray Techniques in Microelectronics
There are several industrial needs that require X-ray systems
with high-brightness X-ray sources:
o Challenges from new materials / smaller dimensions on
wafer (new gate stacks, MRAMs, …): XRD, CD-SAXS, XRF
o Challenges from advanced packaging (micro-bumps,
TSVs): micro- and nano-XCT:
o Combination of techniques (hybrid metrology and
diagnostics):
« Analytical X-ray microscope »
- high-resolution (3D) imaging (nano-XCT)
- high-resolution XRF and XRD
High-flux X-ray Sources
Joe Kline, NIST @ FCMN 2015
Linac ICS
Graves et al, . Phys. Rev. Spec. Top. - Accel. Beams 2014
www.excillum.com
Metal Jet Anode
Synchrotron ICS
www.lynceantech.com
Microstructured Anode
www.sigray.com
e-
Diamond Heat Sink
Talk 15: W. Yun
Thank you!
Contact: [email protected]
Picture: NovaledPicture: Fraunhofer IPMS Picture: GLOBALFOUNDRIES
Martin Gall, Jürgen Gluch, Sven Niese *, Kristina Kutukova,
Fraunhofer IKTS Dresden, Germany
• now with AXO Dresden, Germany
Markus Löffler, Technical University Dresden, Germany
Gerd Schneider, Helmholz Zentrum Berlin, Germany
Wening Yun, Sigray Inc. Concord/CA, US