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Surface Analysis
Surface Analysis
Dr. Lynn FullerDr. Fuller’s Webpage:
http://people.rit.edu/lffeee
ROCHESTER INSTITUTE OF TECHNOLOGYMICROELECTRONIC ENGINEERING
© January 31, 2011 Dr. Lynn Fuller
Rochester Institute of Technology
Microelectronic Engineering
Page 1
1-31-2011 Surface.ppt
Dr. Fuller’s Webpage:
http://people.rit.edu/lffeeeMicroelectronic Engineering
Rochester Institute of Technology82 Lomb Memorial
DriveRochester, NY 14623-5604
Tel (585) 475-2035Fax (585) 475-5041
Email: [email protected] webpage:
http://www.microe.rit.edu
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Surface Analysis
OUTLINE
IntroductionScanning Electron Microscopy (SEM)Transmission
Electron Microscopy (TEM)Atomic Force Microscopy (AFM)Energy
Dispersive Analysis of x-rays (EDAX)Auger Electron Spectroscopy
© January 31, 2011 Dr. Lynn Fuller
Rochester Institute of Technology
Microelectronic Engineering
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Auger Electron SpectroscopyX-ray Fluorescence Spectroscopy
(XPS)Secondary Ion Mass Spectroscopy (SIMS)Capacitance Voltage
MeasurementsSurface Charge Analyzer
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Surface Analysis
INTRODUCTION
Surface analysis refers to a collection of techniques to get
information
about the chemical or physical nature of a surface. (few µm)
© January 31, 2011 Dr. Lynn Fuller
Rochester Institute of Technology
Microelectronic Engineering
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Surface Analysis
LEO EVO 50
© January 31, 2011 Dr. Lynn Fuller
Rochester Institute of Technology
Microelectronic Engineering
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Surface Analysis
AMRAY 1830 1 & 2
© January 31, 2011 Dr. Lynn Fuller
Rochester Institute of Technology
Microelectronic Engineering
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Surface Analysis
PrimaryElectronBeam
SecondaryElectrons, 20Å
AugerElectrons10Å Sintillator
(Phosphor Coated)
+200 V
-2000 V
-3000 V
-4000 V
hv-1000 V
Photo multiplier
R
Vout
SCANNING ELECTRON MICROSCOPE (SEM)
© January 31, 2011 Dr. Lynn Fuller
Rochester Institute of Technology
Microelectronic Engineering
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Characteristic X-rays
1 µm
Back scatteredElectrons
10Å
X-RayContinuum
(Phosphor Coated) Photo multiplierTube (low work Function)
Specimen Current Detector
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Surface Analysis
PrimaryElectron
Beam
Very ThinSpecimen< 1 µm
SpecimenSupportGrid
TRANSMISSION ELECTRON MICROSCOPE
© January 31, 2011 Dr. Lynn Fuller
Rochester Institute of Technology
Microelectronic Engineering
Page 7
< 1 µmSintillator(Phosphor Coated)
Photo multiplierTube (low work Function)
+200 V
-2000 V
-3000 V
-4000 V
-1000 V
R
Vout
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Surface Analysis
TEM OF MOS STRUCTURE
POLY
SiO2
© January 31, 2011 Dr. Lynn Fuller
Rochester Institute of Technology
Microelectronic Engineering
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SiO2
Si
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Surface Analysis
LEO EVO 50 SEM & EDAX
© January 31, 2011 Dr. Lynn Fuller
Rochester Institute of Technology
Microelectronic Engineering
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Surface Analysis
SEM EXAMPLES
© January 31, 2011 Dr. Lynn Fuller
Rochester Institute of Technology
Microelectronic Engineering
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Surface Analysis
SEM EXAMPLES
© January 31, 2011 Dr. Lynn Fuller
Rochester Institute of Technology
Microelectronic Engineering
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Surface Analysis
SEM WITH FOCUSED ION BEAM (FIB)
© January 31, 2011 Dr. Lynn Fuller
Rochester Institute of Technology
Microelectronic Engineering
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Surface Analysis
SEM WITH FOCUSED ION BEAM (FIB)
© January 31, 2011 Dr. Lynn Fuller
Rochester Institute of Technology
Microelectronic Engineering
Page 13
FIB allows crossection SEM images to be made at any point
by cutting a trench with a focused beam of argon ions.
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Surface Analysis
Surface~ 100 Å Gap
X
YZ
SCANNING TUNNELING MICROSCOPE (STM)
© January 31, 2011 Dr. Lynn Fuller
Rochester Institute of Technology
Microelectronic Engineering
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Piezoelectric Motors Scan Tip in X and Y, Electronics control Z
such that the Tunneling Current I is Constant. The Control Voltage
for Z is a Measure of Surface Topology
I
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Surface Analysis
ATOMIC FORCE MICROSCOPE (AFM)
© January 31, 2011 Dr. Lynn Fuller
Rochester Institute of Technology
Microelectronic Engineering
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Surface Analysis
ATOMIC FORCE MICROSCOPE (AFM)
� Standard Sharp Apex Slender Long Used in Contact mode
© January 31, 2011 Dr. Lynn Fuller
Rochester Institute of Technology
Microelectronic Engineering
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� CD Mode (Conical and Flared)
Flared tip able to measure undercut sidewalls
Used in non-contact mode
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Surface Analysis
PrimaryElectron
Beam
CharacteristicX-rays
Back scatteredElectrons
SecondaryElectrons, 20Å
AugerElectrons10Å
ENERGY DISPERSIVE ANALYSIS OF XRAYS (EDAX)
© January 31, 2011 Dr. Lynn Fuller
Rochester Institute of Technology
Microelectronic Engineering
Page 17
X-rays
1 µmX-RayContinuum
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Surface Analysis
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PRIMARYELECTRON
En = -13.6 Z2/n2IRON
Atomic Number26
E1 = -9194 eVE2 = -2298 eVE3 = -1022 eV
ENERGY DISPERSIVE ANALYSIS OF XRAYS (EDAX)
© January 31, 2011 Dr. Lynn Fuller
Rochester Institute of Technology
Microelectronic Engineering
Page 18
KL
M
12
E3 = -1022 eV
E =h ν ν ν ν or λ= λ= λ= λ=h c //// E
KΒ x-ray
Notation: K x-rays are associated with
transitions to 1st shell, L x-rays to the 2nd
shell. α x-rays are between adjacent shells, Β
x-rays are two shells apart, etc.
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Surface Analysis
EDAX
Crystal Detector
© January 31, 2011 Dr. Lynn Fuller
Rochester Institute of Technology
Microelectronic Engineering
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Liquid Nitrogen Cooled
Semiconductor DetectorCryogenic Semiconductor Detector
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Surface Analysis
EDAX
© January 31, 2011 Dr. Lynn Fuller
Rochester Institute of Technology
Microelectronic Engineering
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Surface Analysis
EDAX
© January 31, 2011 Dr. Lynn Fuller
Rochester Institute of Technology
Microelectronic Engineering
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Surface Analysis
EDAX ANALYSIS OF FAILED RF PIN
A
B
© January 31, 2011 Dr. Lynn Fuller
Rochester Institute of Technology
Microelectronic Engineering
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Failed RF Pin: 40XFailed RF Pin: 320X
Point A & B Analyzed using EDAX
A
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20.48KEV 20.48KEV
MLK MODE SELECT ELEMENT
LK Z=30 ZN
PR=S 319 SEC 0 INT
V=4096 H=20KEV 1:1 AQ=20KEV 1H
MLK MODE SELECT ELEMENT
ML Z=80 HG
PR=S 150 SEC 0 INT
V=4096 H=20KEV 1:1 AQ=20KEV 1H
ENERGY KEV ENERGY KEV
CO
UN
TS
CO
UN
TS
POINT APOINT B
20.48KEV20.48KEV
MLK MODE SELECT ELEMENT
LK Z=29 CU
PR=S 319 SEC 0 INT
V=4096 H=20KEV 1:1 AQ=20KEV 1H
MLK MODE SELECT ELEMENT
MLK Z=41 NB
PR=S 150 SEC 0 INT
V=4096 H=20KEV 1:1 AQ=20KEV 1H
ENERGY KEV
ENERGY KEV ENERGY KEV
ENERGY KEV
CO
UN
TS
CO
UN
TS
POINT APOINT B
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Surface Analysis
PrimaryElectron
Beam
CharacteristicX-rays
Back scatteredElectrons
SecondaryElectrons, 20Å
AugerElectrons10Å
AUGER ELECTRON SPECTROSCOPY
© January 31, 2011 Dr. Lynn Fuller
Rochester Institute of Technology
Microelectronic Engineering
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X-rays
1 µmX-RayContinuum
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Surface Analysis
AUGER
© January 31, 2011 Dr. Lynn Fuller
Rochester Institute of Technology
Microelectronic Engineering
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Surface Analysis
AUGER
© January 31, 2011 Dr. Lynn Fuller
Rochester Institute of Technology
Microelectronic Engineering
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Auger analysis showed an aluminum
particle contaminated the wafer.
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Surface Analysis
AUGER
� Simultaneous Process� Ionization of Core Electron� Upper level
electron falls into
lower energy state� Energy release from second
© January 31, 2011 Dr. Lynn Fuller
Rochester Institute of Technology
Microelectronic Engineering
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� Energy release from second electron allows Auger electron to
escape
� The illustrated LMM Auger electron energy is ~423 eV (EAuger =
EL2 - EM4 - EM3)
http://www.cea.com/cai/augtheo/process.htm
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Surface Analysis
AUGER
� Chart of principal Auger electron energies
� Dots indicate electron energies for principal Auger peaks for
each element
© January 31, 2011 Dr. Lynn Fuller
Rochester Institute of Technology
Microelectronic Engineering
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element
http://www.cea.com/cai/augtheo/energies.htm
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Surface Analysis
ESCA or XPS
Electron Spectroscopy for ChemicalAnalysis (ESCA) or X-ray
PhotoElectron Spectroscopy (XPS)
© January 31, 2011 Dr. Lynn Fuller
Rochester Institute of Technology
Microelectronic Engineering
Page 29
X-raySource
Electrons
Sample
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Surface Analysis
Ion BeamGun
MassSpectrometer
SECONDARY ION MASS SPECTROSCOPY (SIMS)
© January 31, 2011 Dr. Lynn Fuller
Rochester Institute of Technology
Microelectronic Engineering
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Sample
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Surface Analysis
Quadrupole FilterGas Sample
The Quadrupole Filter has voltages such that down the center
there is a zero potential equipotential surface. Only ions of a
certain mass make it all the wayto the photomultiplier tube. The
voltage applied to the filter at radio frequencyand DC selects the
mass.
RESIDUAL GAS ANALYZER (RGA)
© January 31, 2011 Dr. Lynn Fuller
Rochester Institute of Technology
Microelectronic Engineering
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R
+1000
Vout
+3000
Quadrupole Filter +2000+4000Lens
Filiment
PhotomultiplierTube
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Surface Analysis
RGA
© January 31, 2011 Dr. Lynn Fuller
Rochester Institute of Technology
Microelectronic Engineering
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Surface Analysis
silicon
εεεε εεεε
Oxide, XoxMetal
CAPACITANCE VOLTAGE MEASUREMENTS
-10 < V < +10
© January 31, 2011 Dr. Lynn Fuller
Rochester Institute of Technology
Microelectronic Engineering
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Cox= εεεεo εεεεr Area/Xox
Apply a DC voltage (V) to the capacitor and measure
the capacitance. High frequency and low frequency
capacitance measurement techniques are available.
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Surface Analysis
CV MEASUREMENTS
V
C
High Frequency
Low Frequency
Accumulation
Depletion
Inversion
Cmin
CFBN-Type Silicon
© January 31, 2011 Dr. Lynn Fuller
Rochester Institute of Technology
Microelectronic Engineering
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V0VFBVT
Cmin
V0
C
High Frequency
Low Frequency
Accumulation
Depletion
Inversion
VFB VT
Cmin
CFBP-Type Silicon
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Surface Analysis
SCA
LED Light SourceCapacitive
Pickup
Signal AmplifierHigh Voltage AmplifierLight Controller and
ModulatorData AcquisitionComputer
© January 31, 2011 Dr. Lynn Fuller
Rochester Institute of Technology
Microelectronic Engineering
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Guard
Electrode
Pickup
Silicon
Oxide
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Surface Analysis
SCA
Qind
Wd
Accumulation
Inversion
WFB+ -
Wmid gapWTP-type Wafer
© January 31, 2011 Dr. Lynn Fuller
Rochester Institute of Technology
Microelectronic Engineering
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Qind0
Wd
Accumulation
Inversion
WFB +-
Wmid gapWT
Qind 0
N-type Wafer
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Surface Analysis
Login: FACTORYPassword: OPER Operate Test Place the blank spot
in middle of wafer on center of the stageSelect (use arrow keys,
space bar, page up, etc)
PROGRAM = FAC-P or FAC-NLOT ID = F990909WAFER NO. = D1TOX = 463
(from nanospec)
SCA-2500 SETUP
© January 31, 2011 Dr. Lynn Fuller
Rochester Institute of Technology
Microelectronic Engineering
Page 37
WAFER NO. = D1TOX = 463 (from nanospec)
start test and wait for measurement print results exit and log
off can be used anytime, but wait for
current test to be completed
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Surface Analysis
EXAMPLE OF SCA OUTPUT MEASURED AT RIT
© January 31, 2011 Dr. Lynn Fuller
Rochester Institute of Technology
Microelectronic Engineering
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Surface Analysis
EXAMPLE OF SCA OUTPUT MEASURED AT RIT
© January 31, 2011 Dr. Lynn Fuller
Rochester Institute of Technology
Microelectronic Engineering
Page 39
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Surface Analysis
REFERENCES
1. Scanning Electron Microscopy, Michael T. Postek, et, al.,
Ladd Research Industries, Inc., 1980.
2. Micro-X7000 Operating Manual, Kevex Corporation, 1101 Chess
Drive, Foster City, CA 94404, 1982.
3. EDAX Inc., 91 McKee Drive, Mahwah, NJ 07430-9978, Tel (201)
529-3156
© January 31, 2011 Dr. Lynn Fuller
Rochester Institute of Technology
Microelectronic Engineering
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3. EDAX Inc., 91 McKee Drive, Mahwah, NJ 07430-9978, Tel (201)
529-3156
4. AFM see, http://spm.phy.bris.ac.uk/techniques/AFM/, and
http://www.fys.kuleuven.ac.be/vsm/spm/images/introduction/afm.html
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Surface Analysis
HOMEWORK: SURFACE
1. Calculate the wavelength of the Kα and LΒ x-ray for
copper.]
2. Explain how SIMS gives doping profiles.
3. Why can’t Auger and a ESCA give doping profiles.
© January 31, 2011 Dr. Lynn Fuller
Rochester Institute of Technology
Microelectronic Engineering
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