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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
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
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
Page 3
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
Page 6
Characteristic X-rays
1 µm
Back scatteredElectrons
10Å
X-RayContinuum
(Phosphor Coated) Photo multiplierTube (low work Function)
Specimen Current Detector
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
Surface Analysis
TEM OF MOS STRUCTURE
POLY
SiO2
© January 31, 2011 Dr. Lynn Fuller
Rochester Institute of Technology
Microelectronic Engineering
Page 8
SiO2
Si
Surface Analysis
LEO EVO 50 SEM & EDAX
© January 31, 2011 Dr. Lynn Fuller
Rochester Institute of Technology
Microelectronic Engineering
Page 9
Surface Analysis
SEM EXAMPLES
© January 31, 2011 Dr. Lynn Fuller
Rochester Institute of Technology
Microelectronic Engineering
Page 10
Surface Analysis
SEM EXAMPLES
© January 31, 2011 Dr. Lynn Fuller
Rochester Institute of Technology
Microelectronic Engineering
Page 11
Surface Analysis
SEM WITH FOCUSED ION BEAM (FIB)
© January 31, 2011 Dr. Lynn Fuller
Rochester Institute of Technology
Microelectronic Engineering
Page 12
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.
Surface Analysis
Surface~ 100 Å Gap
X
YZ
SCANNING TUNNELING MICROSCOPE (STM)
© January 31, 2011 Dr. Lynn Fuller
Rochester Institute of Technology
Microelectronic Engineering
Page 14
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
Surface Analysis
ATOMIC FORCE MICROSCOPE (AFM)
© January 31, 2011 Dr. Lynn Fuller
Rochester Institute of Technology
Microelectronic Engineering
Page 15
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
Page 16
� CD Mode (Conical and Flared)
Flared tip able to measure undercut sidewalls
Used in non-contact mode
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
Surface Analysis
23
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.
Surface Analysis
EDAX
Crystal Detector
© January 31, 2011 Dr. Lynn Fuller
Rochester Institute of Technology
Microelectronic Engineering
Page 19
Liquid Nitrogen Cooled
Semiconductor DetectorCryogenic Semiconductor Detector
Surface Analysis
EDAX
© January 31, 2011 Dr. Lynn Fuller
Rochester Institute of Technology
Microelectronic Engineering
Page 20
Surface Analysis
EDAX
© January 31, 2011 Dr. Lynn Fuller
Rochester Institute of Technology
Microelectronic Engineering
Page 21
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
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
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
Page 24
X-rays
1 µmX-RayContinuum
Surface Analysis
AUGER
© January 31, 2011 Dr. Lynn Fuller
Rochester Institute of Technology
Microelectronic Engineering
Page 25
Surface Analysis
AUGER
© January 31, 2011 Dr. Lynn Fuller
Rochester Institute of Technology
Microelectronic Engineering
Page 26
Auger analysis showed an aluminum
particle contaminated the wafer.
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
Page 27
� 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
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
Page 28
element
http://www.cea.com/cai/augtheo/energies.htm
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
Surface Analysis
Ion BeamGun
MassSpectrometer
SECONDARY ION MASS SPECTROSCOPY (SIMS)
© January 31, 2011 Dr. Lynn Fuller
Rochester Institute of Technology
Microelectronic Engineering
Page 30
Sample
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
Page 31
R
+1000
Vout
+3000
Quadrupole Filter +2000+4000
Lens
Filiment
PhotomultiplierTube
Surface Analysis
RGA
© January 31, 2011 Dr. Lynn Fuller
Rochester Institute of Technology
Microelectronic Engineering
Page 32
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
Page 33
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.
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
Page 34
V0VFB
VT
Cmin
V0
C
High Frequency
Low Frequency
Accumulation
Depletion
Inversion
VFB VT
Cmin
CFBP-Type Silicon
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
Page 35
Guard
Electrode
Pickup
Silicon
Oxide
Surface Analysis
SCA
Qind
Wd
Accumulation
Inversion
WFB+ -
Wmid gap
WTP-type Wafer
© January 31, 2011 Dr. Lynn Fuller
Rochester Institute of Technology
Microelectronic Engineering
Page 36
Qind0
Wd
Accumulation
Inversion
WFB +-
Wmid gap
WT
Qind 0
N-type Wafer
Surface Analysis
Login: FACTORYPassword: OPER<F1> Operate<F1> 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)
<F12> start test and wait for measurement<Print Screen> print results<F8> exit and log off<ESC> can be used anytime, but wait for
current test to be completed
Surface Analysis
EXAMPLE OF SCA OUTPUT MEASURED AT RIT
© January 31, 2011 Dr. Lynn Fuller
Rochester Institute of Technology
Microelectronic Engineering
Page 38
Surface Analysis
EXAMPLE OF SCA OUTPUT MEASURED AT RIT
© January 31, 2011 Dr. Lynn Fuller
Rochester Institute of Technology
Microelectronic Engineering
Page 39
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
Page 40
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
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
Page 41