11/8/99 SFR Workshop - Plasma 1 Small Feature Reproducibility A Focus on Plasma Etching UC-SMART Major Program Award E. Aydil, N. Cheung, D. Graves, E

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


2

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


3

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.


4

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.


5

SFR WorkshopNovember 8, 1999

Nathan W. Cheung

Plasma Processing Effects

Research Students: Yonah Cho Adam Wengrow, Changhan Yun

Website: [email protected]


6

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


7

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


8

(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


9

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


10

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


11

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)


12

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


13

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


14

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


15

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


16

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


17

(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


18

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


19

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( )+=


20

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


21

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


22

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


23

Future Work for 2000-2002

• Development and verification of a unified model to predict particle flux and charge flux related to HDP processing.


24

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


25

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?


26

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


27

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


28

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)


29

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


30

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


31

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)


32

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


33

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


34

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


35

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


36

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)


37

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


38

Steady-State Si Etching Througha Fluorocarbon Overlayer: 100 eV CF3

+


39

Mass Balance Model

Si

SixCyFz

C,F Si,C,F

z

0 1.0

Si C F

MD

Model


40

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)


41

Mass Balance Model, continued

Comparison of Model to MD Simulation

Basis: J+ = 5 mA/cm2


42

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


43

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


44

• Motivation

• Transient Enhanced Diffusion (TED) in Silicon

• Semiconductor Isotope Heterostructures

• Future Work


45

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


46

MOTIVATION

• Shrinking device dimensions: the SIA roadmap

• Doping techniques: ion implantation, diffusion

• A new tool: isotopically enriched Si


47

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.


48

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


49

SELF-DIFFUSION IN SILICON

Native point defects: self-interstitials (I) and vacancies (V)

Si-tracer self-diffusion coefficient:


50

TRANSIENT ENHANCED DIFFUSION (TED)

• The origin of TED: Si interstitial “wind”

• Boron clustering

• The “+1” rule

• The effect of carbon


51

6516 J. Appl. Phys., Vol. 81, No. 10, 15 May 1997 Appl. Phys. Rev.: Chason et al.


52

6522 J. Appl. Phys., Vol. 81, No. 10, 15 May 1997

Appl. Phys. Rev.: Chason et al.


53

6036 J. Appl. Phys., Vol. 81, No. 9, 1 May 1997 Stolk et al.


54


Stolk et al.


55


Stolk et al.


56

SEMICONDUCTOR ISOTOPE HETEROSTUCTURES

• Isotopically engineered semiconductors: the case for self-diffusion studies

• Self-diffusion in Si, Ge, GaAs, AlGaAs, GaP and GaSb


57

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)


58

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


59

Si Self-Diffusion Coefficient

H. Bracht, E.E. Haller and R. Clark-Phelps, Phys. Rev. Lett. 81(2), 393 (1998).


60

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


61

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


62

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


63

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


64

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


65

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


66

Configurations Investigated

6 rods powered 4 rods powered 8 rods powered


67

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


68

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


69

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


70

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)


71

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


72

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


73

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


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)


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)

Documents

11/8/99 SFR Workshop - Plasma 1 Small Feature Reproducibility A Focus on Plasma Etching UC-SMART Major Program Award E. Aydil, N. Cheung, D. Graves, E