11/8/99 SFR Workshop - Plasma
1
Small Feature Reproducibility A Focus on Plasma Etching
UC-SMART Major Program AwardE. Aydil, N. Cheung, D. Graves, E. Haller, and M.
Lieberman,Second Annual Workshop
11/8/99
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Agenda8:30 – 9:00 Introductions, Overview / Spanos9:00 – 10:15 Lithography / Spanos, Neureuther, Bokor10:15 – 10:45 Break10:45 – 12:00 Sensor Integration / Poolla, Smith, Solgaard, Dunn12:00 – 1:00 lunch, poster session begins 1:00 – 2:15 Plasma, TED / Graves, Lieberman, Cheung, Aydil, Haller 2:15 – 2:45 CMP / Dornfeld 2:45 – 3:30 Education / Graves, King, Spanos 3:30 – 3:45 Break 3:45 – 5:30 Steering Committee Meeting in room 775A / Lozes 5:30 – 7:30 Reception, Dinner / Heynes rm, Men’s Faculty Club
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Plasma Milestones, Year 1 Develop spatially resolved Langmuir probe for measurements of electron
and ion density, electron temperature, and plasma and floating potential. Initiate measurements of plasma and process uniformity in LAPS using
spatially resolved diagnostics. Simulations of Cu+ and Ar+ on Co surfaces at 55 eV and 175 eV, at angles
0, 30, 45, 60, 75, 85 degrees. Collections of ion reflection and sputter product energy and angular distributions.
Using MD information, simulations of Cu seed layer deposition in high aspect ratio feature (5/1) under conditions relevant to ionized metal physical vapor deposition (IMPVD) tools.
Development of a working inter-atomic potential for the C-F-H system. Test with trajectory simulations on carbon surfaces. Refinement of low energy reactive ion source based on helicon technology.
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Plasma Milestones, Year 2 Experimental study of plasma and process uniformity using Langmuir
probe, OES, and etch-rate metrology. Design matching networks for real-time control of standing wave ratio on
LAPS and conventional tools. Measurements of H/F radical-surface reactivity at photoresist surfaces. Measurement of photoresist etch kinetics with Ar+/F/H Studies of the structure and kinetics of the mixed CxFyHz layer formed
during fluorocarbon plasma etching.
First experimental determination of Si TED in isotope heterostructures. Secondary Ion Mass Spectrometry (SIMS) study of the Si interstitial
"wind" (has never been detected directly!) Effects of n- and p-type doping on Si TED . Control of TED of Si and dopants with carbon implantation.
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SFR WorkshopNovember 8, 1999
Nathan W. Cheung
Plasma Processing Effects
Research Students: Yonah Cho Adam Wengrow, Changhan Yun
Website: [email protected]
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Goals
1) Layer Transfer Using Plasma Processing for SMART-Wafer -New applications of plasma processing for system integration of photonics, MEMS, and electronics
2) Modeling and experiments on surface charge accumulation during plasma processing -Multiple-species model developed to investigate effect of high density plasmas (HDP) on wafer charging
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Plasma Assisted Materials Processing Lab
• General purpose HPD tools for plasma research (charging studies, etching, implantation, materials modification)
• Large selection of species available (BF3, O2, H2, Ar, N2, F, He, CO2, H2O, plus others).
• Substrate bias 0-80kV DC, and 0-20 kV pulsed-AC.
Plasma Immersion Ion Implanter Large Area Plasma Source
Transformer Coupled Plasma Source
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(1) Progress vs Milestones
Year 1• Single-crystal Si membrane on buried cavities with
thickness good uniformity (<0.3%) and surface micro-roughness (<10nm)
• Plasma surface-activated Si-Si direct bonding and anodic Si-Glass bonding demonstrated.
Year 2• Demonstrate GaN Blue-LED layer transfer• Integration of GaN LED array and c-Si resonator
array in progress
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Motivation: Layer Transfer for System Integration
ElectronicDevices
Membrane by Ion-cut
Integration of Optics, MEMS, and Electronics
GaN LED array by Laser Liftoff
GaN
1m 100m
Si
LED/LASER
Oxide
Membrane
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Ion-Cut Layer Transfer ProcessH+
1. H+ Plasma Implantation
2 Plasma activated Wafer Bonding
Handle waferSi donor
Si donor
Si donor
Bondinginterface
3. Donor wafer cleavagewith heat treatment
Hydrogen inducedSi layer cleavage
Hydrogenpeak
SiO2
Transferred Si overlayer
Handle wafer
Handle wafer
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Results: SOI fabrication by Plasma Implantation
1m
29nm0nm
2m
1m
0m
2m
0m
AFM scan over 2m2m area of transferred silicon layer surface
V bias= -20kV, Dose = 1017 H/cm2, T cut = 550C
Transferred silicon layer, 120nmBuried oxide, 200nm
RMS roughness ~ 4.1nm (as-cut)
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Wafer Bonding with Plasma Surface TreatmentWafer direct bonding
1) Chemical (piranha, HF, RCA) cleaning 2) Plasma surface treatment to increase bond strength
L
2y Wafer t
Razor
Bond strength =
83 Et3y2
L4
Bond Strength Measurement
SiO2 Si
XPS Result before and after Plasma Treatment
112 92Binding Energy (eV)
108 104 100 96
Cou
nts (
a.u.
)
0
5000
1000
beforeafter
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Discussion
380
381
382
383
384
385
-5 -4 -3 -2 -1 0 1 2 3 4 5Position from wafer center (cm)
Si o
verla
yer
thic
knes
s (nm
)
0m
1m
42nm0nm
2m
1m
0m
2m
(a)
(b)
* Membrane thickness uniformity across 100mm wafer is less than 0.3%.
*AFM scan over membrane surface. The as-cut surface micro-roughness is 6nm.
Excellent resonator Q-factor expected from uniform , smooth membranes
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Results: Oxide Membrane Fabrication
Etched Cavity
Handle wafer
H+
1. H+ Implantation & Etching Cavity
2. Wafer Bonding at room temp.
3. Si Cleavage at ~500OC
4. XeF2 Etching of Si overlayer
Siliconon Oxide
Si donor
20 m 100m1m
Optical micrographic top view
SEM Cross-section
Oxide Membrane
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Laser Liffoff and Bonding
1 m
1 m Si
Pd-In
GaN
Pd-In bond
hDevelop methodology for integration of GaN with
Si and GaAs
sapphire
Approach:Approach:1. Low-T In-Pd bond of GaN to Si or GaAs2. Laser Liftoff and transfer of GaN
Si
GaN
GaAs
GaN
sapphire
supportingsubstrate
sapphire
supportingsubstrate
GaN successfully bonded and transferred from sapphire
onto Si
Next stepIntegration of GaN-based LEDs
with Si-based ICs for emitter-detector arrays
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Future Work (2000-2002)• Prototyping of integrated optical, micro-mechanical
resonator and active IC devices on a SMART wafer for real-time processing diagnostics
LED
Thermal Sensor
resonator
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(2) Progress vs. MilestonesYear 1• Develop an ion flux model for multiple-species
plasma• Preliminary results demonstrating mass
attenuation effect with different source apertures
Year 2• Work in progress to verify effective mass
separation using mass attenuation concept• Verification of multiple-species charging
model with various antenna ratios and thin dielectrics
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Multiple-Species Effects on Charging
• Plasma composition will effect charging flux (e.g. molecular gas sources CFx
+, carrier gas ionization, and plasma instability)
A
Field Isolation OxidePoly
MetalOxide
Gate oxide
Photoresist
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Single Ion Species Model
Electron CurrentSecondary Electrons
Displacementni ion densityub ion Bohm velocitys sheath widthM ion massVs sheath voltage
ve electron velocityVp plasma potentialk secondary electron constantVo applied voltageCs sheath capacitance
Jse k VsJion=
Je14---qn ive e
Vp Vs–
Te-------------------------
–
=
Sheath Diff. Eq.
Ion Current Ji49---
o2qM------ 1 2/ Vo
3 2/
s2--------------------=
Ji qnidsdt----- ub+
=
qnidsdt----- ub+ 4
9---
o2qM------ 1 2/ Vo
3 2/
s2--------------------=
Jdisp t( ) Cs t( ) tdd Vs t( )( ) Vs t( ) td
dCs t( )+=
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Multiple Ion Species Model and Results
• Effective mass concept:
• Effective ion Bohm velocity concept:
0.1 1 10 100 1000 10000
12
14
16
18
20
Pulse Width (tw) (s)
Perc
ent B
+ Impl
ante
d (B
+ /BF 2
+ )
0
-5kV
tw
tf =1s
% ubi% i
Total ion density = 1010cm-3
10% B+ / 90% BF2+
I II III2ions of #
1iieff MM
i
density ion of %i
eff
ions of #
1ibii
eff M
Muu
i
iion of velocity Bohm u bi
BF3 Plasma Results
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Plasma Mass Attenuator Set-upWafer BiasProcessing Chamber
Plasma
Magnetic Coils
Microwave &Gas Input
ECR PlasmaSource
Sheath
Biased Ion Shutter Mass/EnergySpectrometer
3/2 " diameter 3/4 " diameter 3/8 " diameter
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Small Diameter Shutter (3/8”)
• 300W -wave power• 5 sccm of both Ar and H• Multi-cusp magnet mode
(240Amps, plasma confined)• No wafer bias
• 300W -wave power• 10 sccm of Oxygen• Multi-cusp magnet mode
(220Amps, plasma not confined)• No wafer bias
Shutter Bias Effects (Ar/H Plasma)
0.E+00
5.E-07
1.E-06
2.E-06
2.E-06
3.E-06
-6 -4 -2 0 2 4 6
Shutter Bias (V)
Mas
s Sp
ec. I
nten
sity
(par
tial
pres
sure
)
amu=40amu=3amu=2
Shutter Bias Effects (Oxygen Plasma)
0.E+00
2.E-07
4.E-07
6.E-07
8.E-07
1.E-06
1.E-06
1.E-06
2.E-06
2.E-06
-6 -4 -2 0 2 4 6
Shutter Bias (V)
Mas
s Sp
ec. I
nten
sity
(par
tial
pres
sure
)
amu=16amu=32
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Future Work for 2000-2002
• Development and verification of a unified model to predict particle flux and charge flux related to HDP processing.
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Plasma-Surface Interactions: Vacuum Beam Experiments and Molecular Dynamics
Simulations
David Graves, Frank Greer, and Cam AbramsUniversity of California Berkeley
Department of Chemical EngineeringWorkshop on SFR
Nov. 8, 1999Berkeley, CA
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Motivation
• Plasma-surface interactions key to controlling plasma effects at feature scale– Most poorly understood part of plasma processing– Complex coupled processes: physical and chemical processes– Events often take place over small length scale and short time scales (e.g.
ion-surface)– Surface chemistry affects feature scale and tool scale phenomena
• How to model feature scale and tool scale processes?– Development of surface process rate expressions– How does PR etch rate depend on ion energy and neutral flux?– How to model processes with simultaneous etch and deposition?
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Plasma-Surface Chemistry in Plasma Etch Tools
Bulk Plasma
Inlet GasFlow
Feature scale
Reactor Scale
Reactive neutral and ionic species
Etch and other reaction product species
Wall Interactions
Reactive/Etching/Depositing Species
Atomic scale
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Schematic of the Beam Apparatus in Cross-Section
Surface Reaction Products
High Energy Ion
Source
Microwave Atom Source
ICP Atom Source
Main Chamber
Analysis Section
Rotatable Carousel
H
+
+
F
+
Quadrupole MassSpectrometer
FacingQuadrupole Mass
Spectrometer
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Etch Yield Results for Olin i-line ResistPhotoresist Etch Yield (Olin Resist)
0
5
10
15
20
25
30
35
40
45
50
0 100 200 300 400 500 600 700 800Fluorine Atom/Argon Ion Flux Ratio
1000 eV Data for Olin
500 eV Data for Olin
Silicon (500 eV)
Silicon Dioxide (500 eV)
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Effect of Hydrogen Atoms at Surface
• Etch Yield Effects– Does adding flux of H atoms to photoresist surface
reduce the Ar+/F atom etch yield?
• Abstraction Chemical Kinetics– What are the abstraction probabilities for the
following?• Incident F abstracting adsorbed H from the photoresist• Incident H abstracting adsorbed F from the photoresist
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Effect of Large Hydrogen Fluxes During EtchingPhotoresist Etch Yield (Shipley g-line Resist)
0
5
10
15
20
25
30
35
0 50 100 150 200 250 300Fluorine Atom/Argon Ion Flux Ratio
Etch
Yie
ld (C
arbo
n A
tom
s R
emov
ed/Io
n)
1000 eV 1000 eVD = 0 D ~ F
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Effect of Other Species on Photoresist Ion-Assisted EtchingEtch Yield v. Neutral/Ion Flux Ratio for 1keV Argon Ions
0
5
10
15
20
25
30
35
40
45
50
0 100 200 300 400 500 600 700 800
Neutral Atom Flux/Argon Ion Flux
Etch
Yie
ld (C
arbo
n A
tom
s R
emov
ed/Io
n)
F2
F2 w/ D
D
1000 eV (Shipley Resist)
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Abstraction Kinetics Experiments1. Expose virgin PR to F atoms 4. Pump out deuterium from system2. Pump out fluorine from system 5. Expose PR to F atoms 3. Expose PR to D atoms 6. Return to step 2
DF 1.
D
D
F
2.
DF
QMS
QCM
3. FQMS
QCM
5.
D
D
4.
DF
6.
D DF D DF
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Time
DF
QM
S Si
gnal
F2 only
Plasmaon
F and F2
Mass Change Upon Exposure to Fluorine
05
101520253035404550
0 500 1000 1500Time (s)
Mas
s G
ain
(Nan
ogra
ms)
Time
D2 only
Plasmaon
D and D2
Mass Change Upon Exposure to Deuterium
05
101520253035404550
0 500 1000 1500
Time (s)
Mas
s Lo
ss (N
anog
ram
s)• Surface gains mass as D is replaced by F• F does not etch PR, so mass gain saturates
• Mass loss due to slow PR etching from D atoms
• D does not abstract F to form DF DF ~ 0
• F abstracts D and replaces it on surface•DF signal declines as D is depleted from surface
FD = 0.06
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Model Predictions of Effect of D Atom Flux
0
5
10
15
20
25
30
35
0 50 100 150 200 250 300Fluorine Atom/Argon Ion Flux Ratio
Etch
Yie
ld
Etch Yield with D Recomb. Prob. = 0
PR Etch Yield Model Fit to Data
Etch Yield with D Recomb. Prob. = 0.2
4
F
D
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Molecular, Reactive Ion-Surface Interactions: CFx
+ on Si
Many plasma etching applications include molecular ions that can fragment on impact and that can both deposit and etch.
CFx+
Si
SixCyFz
Mixed layer structure especially complicated with depositing species present in the ion (e.g. C or Si). What is thickness, composition, profile within layer? What controls etch rate? What determines transition between etching and deposition?
Can we develop and apply a site balance model of the mixed layer?
SixCyFz mixed layer
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Molecular Dynamics (MD) Simulation
• Simulates the motion of a collection of several hundred to several thousand coupled atoms
• Interatomic potential energy function (PEF) governs the forces atoms exert on each other
• Numerical integration of the atomic equations of motion until steady state is reached
• For C-F: Tersoff/Brenner/Tanaka PEF; accounts for neighboring atom influence on bonding
• Added Si for a Si-C-F PEF (Abrams)
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Interatomic Potential(Tersoff/Brenner Formalism) Simulation Scheme
Introduce ion above surface
Integrate using MD
Desorb weakly boundclusters, cool to Ts
Repeat x2000
i j
U i ij
j i
Molecular Dynamics Simulations of CFx+/Si
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Steady-State Si Etching Througha Fluorocarbon Overlayer: 100 eV CF3
+
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Mass Balance Model
Si
SixCyFz
C,F Si,C,F
z
0 1.0
Si C F
MD
Model
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Mass Balance Model, continued
LJ
dF
dt F Ps
F,0 1 F YF ,0F Y0FF
LJ
dC
dt C Ps
C,0 1 F Y0FC
Si 1 F C
Si 0 1.0, F 0 C 0 0.0
= Sites/cm3; L = depth; J+ = ions/(A•cm2)
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Mass Balance Model, continued
Comparison of Model to MD Simulation
Basis: J+ = 5 mA/cm2
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Second Year Plans• Measure effects of surface temperature and surface
type on photoresist etch/abstraction chemistry in beam experiments
• Add neutral radical (F, CFx) impact to MD simulations
• Further development of phenomenological models for fluorocarbon chemistry
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TRANSIENT ENHANCED DIFFUSION (TED) IN ISOTOPICALLY ENGINEERED
SILICON
Hartmut A. Bracht, Cynthia B. Nelson and
Eugene E. HallerUniversity of California at Berkeley
andLawrence Berkeley National Laboratory
SFR-UCB SMART, Nov. 8, 1999
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• Motivation
• Transient Enhanced Diffusion (TED) in Silicon
• Semiconductor Isotope Heterostructures
• Future Work
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COLLABORATORS
• Joel W. Ager III, LBNL
• Steven Burden, ISONICS Corp., Golden, CO
• Manuel Cardona, MPI Stuttgart, Germany
• Nick Cowern, Phillips Eindhoven, Holland
• Hans Gossmann, Bell Labs, Lucent Techn., Murray Hill, NJ
• William Hansen, LBNL
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MOTIVATION
• Shrinking device dimensions: the SIA roadmap
• Doping techniques: ion implantation, diffusion
• A new tool: isotopically enriched Si
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6515 J. Appl. Phys., Vol. 81, No. 10, 15 May 1997 Appl. Phys. Rev.: Chason et al.
• The in-plane dimension reductions (e.g. gate length) demand equivalently shallower implantation and diffusion depths.
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Dominant Diffusion Mechanisms in Silicon
- Interstitial assisted diffusion (kick-out mechanism)
AS + I <=> AI
- Vacancy assisted diffusion (Frank-Turnbull or dissociative mechanism)
AS <=> AI + V
(A = Si or impurity)
Self-diffusion coefficient DSD:eqVV
eqII
SD CD+CD=D
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SELF-DIFFUSION IN SILICON
Native point defects: self-interstitials (I) and vacancies (V)
Si-tracer self-diffusion coefficient:
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TRANSIENT ENHANCED DIFFUSION (TED)
• The origin of TED: Si interstitial “wind”
• Boron clustering
• The “+1” rule
• The effect of carbon
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6516 J. Appl. Phys., Vol. 81, No. 10, 15 May 1997 Appl. Phys. Rev.: Chason et al.
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6522 J. Appl. Phys., Vol. 81, No. 10, 15 May 1997
Appl. Phys. Rev.: Chason et al.
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6036 J. Appl. Phys., Vol. 81, No. 9, 1 May 1997 Stolk et al.
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6037 J. Appl. Phys., Vol. 81, No. 9, 1 May 1997
Stolk et al.
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6041 J. Appl. Phys., Vol. 81, No. 9, 1 May 1997
Stolk et al.
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SEMICONDUCTOR ISOTOPE HETEROSTUCTURES
• Isotopically engineered semiconductors: the case for self-diffusion studies
• Self-diffusion in Si, Ge, GaAs, AlGaAs, GaP and GaSb
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ISOTOPE MULTILAYER STRUCTURES
• naturalSi = 92.23% 28Si + 4.67% 29Si + 3.10% 30Si
• Post Cold War collaborations with Russian and Ukranian scientists have given us access to highly enriched 28Si (99.95%)
• Lawrence Semiconductor Research Corporation in Tempe, AZ has grown undoped and doped multilayer structures:
natSi (2 m) : 28Si (2 m) : natSi (substrate wafer)
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as-grown 30Si profile
diffused 30Si profile
(1322°C/30min)[ 30
Si ]
(cm
-3)
nat.Si = 92.23% 28Si + 4.67% 29Si + 3.10% 30Si
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Si Self-Diffusion Coefficient
H. Bracht, E.E. Haller and R. Clark-Phelps, Phys. Rev. Lett. 81(2), 393 (1998).
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FUTURE WORK: TED RESEARCH MILESTONES YEAR 2
• First experimental determination of Si TED in isotope heterostructure
• Secondary Ion Mass Spectroscopy (SIMS) studies of Si interstitial wind (has never been detected directly!)
• Effects of n-type and p-type doping on Si TED
• Control of TED of Si and dopants with carbon implantation
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Plasma Sources for Small Feature Reproducibility
A.J. Lichtenberg†, M.A. Lieberman†, A.M. Marakhtanov† and Yaoxi Wu*
Departments of†Electrical Engineering and Computer Sciences
*Materials Science and EngineeringUniversity of California, Berkeley
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MotivationScaling inductive sources to larger sizes (LAPS)• Usual external coils give inherently nonuniform power deposition over large areas - use internal coil• Antenna standing wave effects lead to plasma nonuniformities - employ traveling wave antenna
Controlling instabilities in inductive sources (TCP)• Instabilities are observed in commercial inductive discharges with electronegative gas feeds – determine stable/unstable operating parameter windows (power, pressure, gas feed mix, etc)– develop a theory of the instability to learn how to control it
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Large Area Plasma Source• Antenna coil
embedded in the plasma
• Eight quartz tubes threaded by copper antenna tubes
• Eight vertical gas feed lines with equally spaced pin-holes
• 71 cm x 61 cm plasma area
Irf
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Progress vs. Milestones
Year 1• Develop spatially resolved Langmuir probe for measurements
of plasma properties (done)• Initiate measurements of plasma uniformity in LAPS using
spatially resolved diagnostics (done)Year 2• Experimental study of plasma and process uniformity using
Langmuir probe and OES (on-going)• Study effect of alternative coil configurations on plasma
density profile (on-going)
LAPS
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LAPS Driving Circuit
(a) Power supply (b) Matching
network (c) Tuning
network (d) Antenna and
plasma system
Traveling waves are launched by a tuning network
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Configurations Investigated
6 rods powered 4 rods powered 8 rods powered
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Six Rods Powered – Experimental Results
•Density profile for p = 5.8 mTorr, varying power
•Density profile for P 1211 W, varying pressure
0 20 40 60 80 1000.00E+000
5.00E+016
1.00E+017
1.50E+017
2.00E+017
2.50E+017
p = 5.8 mTorr, d = 5.45 cm for different power 408 W
508 715 818 839 1208 1848 2081 2481
Pla
sma
dens
ity (m-3
)
Position0 20 40 60 80 100
0.00E+000
5.00E+016
1.00E+017
1.50E+017
2.00E+017
2.50E+017
3.00E+017
3.50E+017
4.00E+017
d = 5.45 cm for different pressure
1201 W, 1.4 mTorr 1208 W, 5.8 mTorr 1211 W, 14 mTorr 1241 W, 43 mTorr
Pla
sma
dens
ity (m
-3)
Position
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Eight Rods Powered• Density profile - without tuning• Density profile - with tuning
0 20 40 60 80 1000.0
2.0x1016
4.0x1016
6.0x1016
8.0x1016
1.0x1017
P = 823 W, p = 14 mTorr
With tuning Without tuning
Pla
sma
dens
ity (m
-3)
X axis title
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Capacitive
450 WUnstable595 W
Inductive900 W
End-On View of 5.4 mTorr SF6 Discharge
TCP Experiment
PlasmaPlasma
Inductive Inductive CoilCoil
Langmuir ProbeLangmuir Probe
PMTPMT
Video Video
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Progress vs MilestonesTCP SourceYear 1• Mapped inductive plasma instability regions inside TCP
source. (Done)• Observation of optical emission modulations due to
instabilities. (Done)• Develop theoretical model of instabilities (Done)Year 2• Add additional TCP plasma diagnostics. (Done)• Further develop theory for electronegative instabilities in
inductive discharges. (on-going)• Bring high flow Lam oxide etch prototype on-line. (on-going)
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Langmuir probe current time history pSF6 = 5.2 mTorr, 500 W
PROB
E CU
RREN
T,
A
TIME TIME
V=28 V
V=14 V
V=10 V
V=0
V=-14 V
V=-28 V
-300
- 460
- 620
- 15
- 30
- 45
- 1
- 9
- 17
0 0.2 ms 0
00
00
0.2 ms
0.2 ms
0.2 ms
0.2 ms
0.2 ms
14
10
6
29
25
21
44
40
36
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Range of Instability in SF6 Discharge
0 10 20 30 40 50 60 70 80 90 100300
400
500
600
700
800
900
Pressure, mTorr
Pow
er, W
Instability
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Fluctuation of Light Emission vs. Power
400 500 600 700 800 9000
20
40
60
80
100
Power, W
Freq
uenc
y of
ligh
t sig
nal,
kHz
SF6
10 mTorr
25 mTorr
90 mTorr80 mTorr
65 mTorr50 mTorr
40 mTorr
11/8/99 SFR Workshop - Plasma
74
Theoretical Model of Instability
10-4
10-2
10010
-1
100
101
nen -
0
0.4
n e
0
5
n -
0
10
T e
0
20
0
0.4
-
0 1 2 3 4 5 6 7 8 9 100
1
t,ms
optic
al e
mis
sion
pSF6 = 5 mTorr, ICOIL =8.2 A
dne/dt=0
dn-/dt=0
(1010 cm-3)
11/8/99 SFR Workshop - Plasma
75
Future WorkLAPS• Investigate material etching rate and uniformity; e.g., oxygen
etching of photoresist, & correlate with plasma profiles (Year 1)• Optimize etching uniformity using alternative tuning networks to
control antenna standing wave ratios (Year 1)• Investigate real time control of plasma uniformity using the tuning
network. (Year 2)TCP• Continue work, characterizing the influence of the matching
network and power supply on the instability (Year 1)• Initiate instability studies on a Lam high flow oxide etch prototype
TCP reactor (Year 1)• Incorporate matching network in instability theory (Year 2)