Transcript Slide 1

Computer-Based Simulations Providing
Unintuitive and Elusive Electrochemical Data
Uziel Landau1,2
and
Eugene Malyshev2, Sergey Chivilikhin2
1
Department of Chemical Engineering
Case Western Reserve University
Cleveland, Ohio 44106 USA
2
L-Chem, Inc.
Beachwood, OH 44122 USA
[email protected]
[email protected]
(216) 368-4132
EAST FORUM - 2002 * FEM – Oct. 2002
Outline
 Introduction
 Select (new) features of Cell-Design




Fluid-flow and mass transport
Roughness indication
Multiple electrode reactions: Alloys, corrosion.
Resistive film and resistive deposit – anodizing
 Sample applications






Plating of isolated feature
Potential distribution near misaligned electrodes
Empirical verification of Brugemann’s Eqn.
Shunt currents
Leveling by periodic reverse plating
Resistive contacts
 L-Cell (Patent Pending)
 Conclusions
CAD for Electrochemical Systems
• The need for modeling and CAD:
–
–
–
–
–
–
Predictive design instead of ‘trial and error’
Improved product
Process optimization: Find optimal operating conditions
Scale-up and scale-down
Correct interpretation of experimental results
Selling and Marketing tool
• Rationale for CAD Gaining Broad Acceptance:
– More demanding applications
– Wider availability of more powerful desktop computers
AVAILABILITY OF ELECTROCHEMICAL CAD PACKAGES
(ESTIMATE)
16
12
Number of
Programs
8
Elsyca
PC
Cell-Design
4
Mainframe
0
1
1978
3
5
7
9 11 13 15 17 19 21 23 25
2002
Years
New/enhanced in…
Cell-Design 2002
• Fluid-flow / agitation
Translational and rotational flow
 Air agitation (bubble induced convection)

• Roughness indication
• Anodizing – including duplex films
• Multi-electrode reactions
 Alloy plating, parasitic reactions
 Corrosion, cathodic protection
• Battery/fuel cell simulation
• Resistive film and resistive deposit
• L-Cell (Patent Pending)
Strip across a nozzle
Nozzle between
parallel electrodes
Fluid-flow/Agitation
module
• Integrated with the electrochemical
•
•
•
•
simulation
Free & translating boundaries, immersed
objects
Rotational flow/rotating electrodes
Air agitation (bubble induced convection)
Fast and accurate
Impinging flow
Flow past micro-scale roughness
Flow in expanding/converging manifold
Flow past a ‘comb’ pattern
FLOW CHANNEL
3 cm
5 cm
0.16
FLOW:
1 – 25
cm3/sec
Re = 1000
0.12
iL
[A/cm2]
0.08
Theory
Cell-Design Simulation
0.04
0
0
0.5
1
1.5
2
2.5
Distance from Leading Edge [cm]
3
0.06
6.00E-02
Re = 2500
0.05
5.00E-02
iL = 1.0767(nFDCB/de) (Re Sc de/x)1/3
0.04
4.00E-02
iL
[A/cm2]
Cell-Design Simulation
0.03
3.00E-02
0.02
2.00E-02
Re = 100
0.01
1.00E-02
0.00E+000
0
0
0.5
0.5
1
1
1.5
1.5
2
2
Distance from Leading Edge [cm]
2.5
2.5
3
3
100
Sh/Sc1/3
Cell-Design
10
Shavg / Sc1/3 = 1.615 (Re de / L)
1
100
1000
Re
10000
ROUGHNESS EVOLUTION ALONG THE CHANNEL
FLOW
smooth
SMOOTH
ROUGH
Re = 1000; iL = 20.2 mA/cm2; 0.24 M CuSO4 + 1M H2SO4
iavg / iL, avg
iavg
[mA/cm2]
6
0.96
5
0.95
4
0.93
3
0.88
2
0.77
1
19.5
ROUGH DEPOSIT
19.3
ROUGH DEPOSIT
18.8
ROUGH DEPOSIT
smooth
ROUGH
smooth
17.7
15.7
Smooth Deposit
0
0.5
1
1.5
2
2.5
Distance from Leading Edge [cm]
3
PLATING OF AN ISOLATED LINE
80 mills
Anode
Flow : 10 cm/sec avg.
speed
20 mills
2 x 2 mill holes at 2 mill spacing
Avg. current density within
holes = 30 mA/cm2
20 mills
One isolated hole
Plated regions
Photoresist
40 mills
0.24 M CuSO4 + 1M H2SO4
Geometry
Primary Distribution
[ ηΩ >> ηa + ηc ] :
Primary Distribution
[ ηΩ >> ηa + ηc ] :
 ~ 2 mV
a ~ 180 mV
Secondary Distribution [ ηΩ ~ ηa >> ηc ] :
Δ ~ 1.88%
30.38 mA/cm² (Avg. )
30.95 mA/cm²
Geometry
i ~ 30
[mA/cm2]
Flow field
iL =
370
520
540
620 960
1490
[mA/cm2]
Tertiary Distribution [ ηΩ ~ ηa ~ ηc ] :
Δ~ 6.42%
Avg. 28.68 mA/cm²
30.52 mA/cm²
Primary:
Secondary:
Tertiary:
Primary:
Secondary:
Δ ~ 1.88%
30.38 mA/cm² (Avg. )
30.95 mA/cm²
Tertiary:
Δ ~ 6.42%
Avg. 28.68 mA/cm²
30.52 mA/cm²
Copper plating for 77 min.
Porous Anodic Oxide Films :
• Hexagonal Columnar Structure
• Compact Barrier Layer


High resistivity
Thickness = f ( T, V )
• Growth of Porous Layer


Low resistivity
Thickness = f (T, V, t )
ANODIZATION
Copper plating
27
mA/cm2
(avg.)
Aluminum anodizing
37
mA/cm2
(avg.)
105  cm
Barrier:
150 nm
106  cm
CELL DESIGN’s Expert System:
Geometry
Operating
conditions
Solver
Current distribution
Deposit thickness
Polarization
Curve
Part Geometry
Cell-Design
Measured thickness
of anodized layer
Alloy Plating
PLATED PART
• Composition / thickness variation with
•
•
position and current
Co-deposition of additives and
contaminants
Process parameters can be easily
generated using the ‘expert system’ from
measured composition and thickness
(Cathode)
ELECTROLYTE
ANODE
Deposit thickness
distribution
Partial currents along part
Alloy composition along part
Potential distribution
Positioning
of
Reference Electrodes
U. Landau, N.L. Weinberg and E. Gileadi, ‘Three Electrode measurements in Industrial
Cells’, J. Electrochem. Soc. 135 (2), 396 (1988)
Optimal Positioning of Reference Electrodes Our objective:
Ref
+
-
ηa = V – E0 – ηC – η (IR)
measure
Ref
Minimize
or calc.
?
Ref
Model system:
 = 0.05 S/cm
E=0
V = 2.6 V
Ref
Cathode:
i0 = 10-6 A/cm2
ac = 0.5
Anode: reversible (‘Primary’)
U. Landau, N.L. Weinberg and E. Gileadi, ‘Three Electrode measurements in Industrial Cells’, J.
Electrochem. Soc. 135 (2), 396 (1988)
Optimal Positioning of Reference Electrodes -
i = 49 mA/cm2
a= 555 mV
= 100 mV
Expected readings: VRef = 655 mV (= E + a +  ) = (0 + 555 + 100)
Actual readings:
VRef = 552 mV (= E + a +  ) = (0 + 522 + 30)
Da= -33 mV (iref = 26 mA)
D= -70 mV
U. Landau, N.L. Weinberg and E. Gileadi, J. Electrochem. Soc. 135 (2), 396 (1988)
Optimal Positioning of Reference Electrodes -
i = 49 mA/cm2
a= 555 mV
= 100 mV
Expected readings: Vref = 655 mV (= E + a +  ) = (0 + 555 + 100)
Actual readings:
Vref = 552 mV (= E + a +  ) = (0 + 522 + 30)
Da= -33 mV (iref = 26 mA)
D= -70 mV
U. Landau, N.L. Weinberg and E. Gileadi, J. Electrochem. Soc. 135 (2), 396 (1988)
Optimal Positioning of Reference Electrodes Backside Luggin Capillary:
Ref
Ref
i = 250 mA/cm2
a= 638 mV
Expected: VRef = 638 mV (= 0 + 638 + 0)
Measured: VRef = 1325 mV (= 0 + 727 + 598)
Da= 89 mV
D= 598 mV
i = 250 mA/cm2
a= 638 mV
Expected: VRef = 638 mV (= 0 + 638 + 0)
Measured: VRef = 717 mV (= 0 + 669 + 48)
Da= 31 mV
D= 48 mV
Optimal Positioning of Reference Electrodes In insulated manifold:
Current lines
Equi-potential lines
Ref
i = 50 mA/cm2
a= 557 mV
= 1000 mV (= iL/2)
Expected readings: VRef = 1557 mV (= E + a +  ) = (0 + 557 + 1000)
Actual readings:
VRef = 1458 mV (= E + a +  ) = (0 + 528 + 930)
Da= -29 mV
D= -70 mV
Reference Electrode
in a
Narrow Gap Cell -Effect of a slight misalignment
To measure overpotential in an electrode stack –
contact reference electrode to the separator;
expect to measure ½ IR
However…
A slight misalignment (order of the
gap) may lead to erroneous and
unexpected results when the gap
is narrow
1 mm
membrane
Ref
1mm
Electrolyte
Insulator
Perfect alignment Ref. electrode measures
mid-way potential
i ~ 100 mA/cm2
i0 = 10-6 A/cm2
Perfect alignment Ref. electrode measures
mid-way potential
i ~ 100 mA/cm2
i0 = 10-6 A/cm2
Misalignment ~ gap -Ref. electrode measures
potential close to the extended
electrode
Misaligned electrodes in electrolyte
pool (insulate. back and edge)Ref. electrode measures potential
close to the extended electrode
Misaligned electrodes in electrolyte
pool (insulated back)Ref. electrode position is critical
?
Current density is high at edge of
‘symmetrical’ electrodes
Current density is low at
edge of extended electrode
CURRENT DISTRIBUTION
Current density is high at edge of
‘symmetrical’ electrodes
Current density is low at
edge of extended electrode
Current density is low at
edge of extended electrode
Copper Metallization of
Semiconductor Wafer
Interconnects
Typical Chip
Cross-Section
with
Conventional Al
Interconnects
‘Interconnects’
Aluminum
Conductor
Transistor ‘Gate’
Based on Sematech’s
roadmap, 1999
DEVICE SPEED/PERFORMANCE vs.
SIZE
r
SiO2
Device
τ = RC
R = ρ L/A
[Resistance]
= ρ L / π r2
As r decreases,
Resistance increases
Solution:
Lower ρ (resistivity)
Lower K (dielectric const.)
Longer Time delay
DEVICE
Trenc
h
Via
INTERCONNECT
GATE
Smaller line size
Resistivity:
Al
2.65 μ Ω cm (3.0)
Cu
1.68 μ Ω cm (2.0)
Ag
1.59 μ Ω cm
DEVICE SPEED/PERFORMANCE vs. SIZE
45
40
Delay [pico-seconds]
35
Gate + Al + SiO2
Gate + Al + SiO2
30
25
Intercon.
Cu + Low K
20
Gate + Cu
+ Low K
15
10
5
Gate + Cu
+ Low K
Below ~ 0.25 microns, the
interconnects dominates the time
delay.
Resistivity:
Al
2.65 μ Ω cm (3.0)
Cu
1.68 μ Ω cm (2.0)
Ag
1.59 μ Ω cm
Ta
Ti
TaN
12.45
42
135
Dielectric Constant:
SiO2
K = 4.0
‘Low K’ K = 2.0
Gate
‘Cu / Low K’ buys ~ 2 generations
Intercon.
Gate
only
Assumptions- Al and Cu:
Al + SiO2
Trenches: 0.8 μm thick
Lines:
436 μm long
0
-0.65
0.65
-0.55 0.35
-0.45 0.25
-0.35 0.18
-0.25 0.13-0.15 0.1
0.5
Generation (Line Width, μm )
After J. Dahm and K Monnig, Sematech,
AMC 1998 Conf. Proceedings, pp. 3-15.
Data from: M. T. Bohr, Proceedings 1995
IEEE Int. Electron Device Meeting, pp. 241242
Interconnect Copper Metallization
Dual Damascene process:
Etch Via
SiN Etch stop
Insulator (SiO2)
Alternate routes for copper
metallization:
 PVD
 CVD
 Electroless plating
 Electroplating
Etch
Trench
Electroplate
copper
CMP
PVD
Barrier
(Ta, TaN,
Ti or TiN)
&
Cu Seed
Feature Fill – Time Evolution
Short time
Final
‘Normal’ or
‘Subconformal’
deposition
☺
VOID
‘Conformal’
deposition
(highly passivated
system)
☺
SEAM
‘Bottom-up’
or
‘Superfill’
☺
Variable Adsorption leads to Variable Kinetics and
to ‘bottom-up’ fill:
Suppressor, e.g.
PAG
‘Enhancer’, e.g.
Organic di-sulfide
Fast deposition
Slow deposition
Variable Deposition Rates Due to Non-uniform Inhibition
Polarization curves
i
[mA/cm2]
No inhibitors
100
(via)
Suppressed
kinetics
(‘flat’ wafer)
20
300 mV
V
‘Bottom-up’ fill of
trenches and vias
Simulation of Deposit Propagation
Variable kinetics + Moving boundaries
Virtual electrode;
Outer edge of diffusion layer
 2  =0
i = f (η)
aF
F 

iio exp( a )exp(  a ) 
RT
RT 

 2 C =0
Passivated kinetics
(Measured)
IBM’s Model:

Interpolate kinetics
1
1  b N *Ap
Accelerated kinetics
(Measured, or pure copper)
Cell-Design’s
Variable Kinetics
Copper Interconnect Metallization
Trenches: 0.4  wide, 1  deep
‘Normal’ Plating
High current density
Pinch
Unacceptable
‘Conformal’ Plating
Low current density
Unacceptable Concentrations map
Seam
Deposit Growth Profiles
Variable kinetics:
‘Bottom-up’ - ‘super-fill’
Good !
Time evolution
Deposit Propagation Simulation
Variable kinetics + Moving boundaries
Flat regions - Passivated: i0 =5x10-4 A/cm2 a 1.7   0.3
Bottom – Pure copper:
Side-walls - interpolated
i0 =10-3 A/cm2
a 1.5   0.5
Cell Issues
-
-
Practical complications:
Resistive substrate
-
500Å Cu seed
( 0.34 /cm)
i ~ 50 mA/cm2
33 - 344 mA/cm2
+
Ideal –
perfect
cylinder
+
Flow
• Entrance and exit
• Additives distribution
• Kinetics
Power
ELECTROLYTE CONDUCTIVITY
1.5
DEPOSIT THICKNESS [micron]
1.45
1.4
 = 0.55  -1cm-1 (1.8 M Acid)
1.35
1.3
1.25
1.2
1.15
 = 0.05 (No Acid)
1.1
1.05
1
0.0E+00
2.0E+00
4.0E+00
6.0E+00
8.0E+00
1.0E+01
1.2E+01
RADIAL POSITION [cm]
i= 20 mA/cm2
200 mm wafer. 1000A copper seed. Time step growth simulations
‘Cell-Design’© simulations
Effect of Electrolyte Conductivity
iavg~ 35 mA/cm2
C
L
Electric Contact
SEEDED WAFER
C
L
Electric Contact
SEEDED WAFER
20s
20s
PLATED
COPPER
40s
60s
40s
PLATED
COPPER
80s
80s
100s
100s
Final Copper
Profile
60s
Final Copper Profile
1.8 M H2SO4
1.8 M Sulfuric Acid
Thickness ratio = 1.4
No Acid
No Added Acid
Thickness ratio = 1.1
‘Cell-Design’© simulations
THICKNESS [microns]
SEED THICKNESS
SEED

1.6
A
1/cm
1.5
500
0.55
1.57
1.4
1000
0.55
1.42
500
0.05
1.3
Ratio
1.10
1.2
1.1
1000
0.05
1.09
1
0.9
0.00E+00
2.00E+00
4.00E+00
6.00E+00
8.00E+00
1.00E+01
1.20E+01
RADIAL POSITION [cm]
i= 20 mA/cm2
200 mm wafer. Time step growth simulations
‘Cell-Design’© simulations
CURRENT DENSITY
DEPOSIT THICKNESS [microns]
1.7
Current Density
1.6
60 mA/cm2
1.5
40 mA/cm2
1.4
20 mA/cm2
1.3
1.2
1.1
10 mA/cm2
1
0
2
4
6
8
10
12
RADIAL POSITION [cm]
Conductivity = 0.55  -1cm-1 (1.8 M Sulfuric Acid)
200 mm wafer. 1000Å copper seed. Time step growth simulations
‘Cell-Design’© simulations
Resistive Contact Effect
in
Copper Metallization of
Semiconductor Wafer
Interconnects
Copper
TaN
COPPER DISSOLUTION AT CONTACT POINTS
DUE TO HIGH CONTACT RESISTANCE
EXTREME CASE OF COPPER
DISSOLUTION
Picture of wafer with dissolved seed
Copper
TaN
ANOTHER EXTREME CASE
TaN
SHEET COPPER
300 mm
Wafer
COPPER RESIDUE
IN THE FORM OF
EQUIPOTENTIAL
CONTOUR LINES
Current flow through a
non-resistive contact
Wafer
Contact
-
Cu++
Cu++
Anode
Power
Supply
Cu++
+
Current flow through a
resistive contact
Resistive contact
Wafer
-
Cu++
Cu++
Anode
Power
Supply
Cu++
+
Current
Distribution on a
Wafer with a
Non-resistive
contact
Cell-Design®
Details of current distribution
near resistive contact
ANODIC REGION ON WAFER
CATHODIC REGION ON WAFER
Current Distribution on a Resistive
Wafer with a Resistive Contact
Substrate Thickness:
1000 Å: 0.167 Ω/sq
Cu dissolution
Cu plating
Cell-Design® simulation
Voltage
Driving force for current:
 Solution – Velectrode
Vwafer
Solution
Plating on wafer
VAnode
Slightly
resistive
contact
VContact
Contact
Voltage
Driving force for current:
 Solution – Velectrode
Contact
VContact
Resistive
contact
Plating on
contact
Vwafer
Solution
Current reversal
(Dissolution)
Plating on wafer
VAnode
Threshold for Resistive Contact
Current Density (mA/cm^2)
40
Contact Resistance [ohm]:
30
Dissolution
Current
0.25
0.04
20
0.01
10
Bi-polar threshold
0
Deposition region
-10
-20
0
1
2
3
4
5
6
7
Radial Position (cm)
8
9
10
Resistance due to Bubbles
Conduction in Heterogeneous Media
 Maxwell – dilute dispersions
 Bruggeman – concentrated dispersions
 Tobias – gas evolving electrodes (1959)
 Meredit and Tobias - emulsions (1961)
 Sides and Tobias – bubbles on electrodes (1980’s)
 effective
 1  f 
 continuum
3
f 
2
Bubblevolum e
Total volum e
Simulation approach:
Cell size: 3.6 cm * 3.6 cm * 1 cm
Bubble diameter: 0.3 cm
Voltage: V(left electrode) = 0 V
V(right electrode) = 0.28 V
Electrolyte conductivity: = 1 S/cm
Potential Distribution Map
Current Density Map
1
0.9
0.8
0.7
Keff
0.6
Kelectrolyte
0.5
 effective
 1  f 
 continuum
3
0.4
2
0.3
0.2
0.1
0
0
0.2
0.4
0.6
Void volume
Total volume
0.8
1
Shunt Currents in Bi-polar
Electrode Systems
Bi-Polar
Electrode
Shunt
Current
+
Highly reversible Kinetics
Irreversible
Kinetics:
i0 = 10-6 A/cm2
0.3
i0
[A/cm2]
10-10
0.25
Shunt
current
0.2
10-6
0.15
[A]
0.1

(primary)
0.05
0
0
0.5
1
1.5
2
2.5
Bottom Gap [cm]
3
3.5
0.3
i0
[A/cm2]
10-10
0.25
Shunt
current
0.2
10-6
0.15
[A]
0.1

(primary)
0.05
0
0
0.5
1
1.5
2
2.5
Bottom Gap [cm]
3
3.5
250
200
Shunt
current
density
[A/cm2]
i0
[A/cm2]
150
100
10-10
10-6
50

0
0
0.5
1
1.5
2
Bottom Gap [cm]
2.5
3
3.5
Simulation of Periodic
Reverse Plating for Effective
Leveling
Periodic Reverse Plating for Effective Leveling
  a
b
 RT 1
Wa =
=
=
L i
Li
L F ai
+0 V
(In the Tafel range)
Wa >> 1 Uniform Distribution
Wa << 1 Non-Uniform Distribution
0.5
V
+0 V
To achieve uniform deposit
thickness, apply periodic reverse
plating with:
 High Wa during plating (for level
deposition):
 Low current density
 Low aC
 Low Wa during dissolution (for
non-uniformity)
 High current density
 High aA
+1 V
0V
U. Landau, Extended Astract, ECS Meeting, Hawaii, October 1993
+1 V
Periodic Reverse Plating for Effective Leveling
Deposit thickness:
DC Plating : - 0.5 V ~ 100 mA/cm2
4 x 600 min
Periodic reverse :
Plate: - 0.5 V ~ 100 mA/cm2 1200 min
Dissolve: 1 V ~ 300 mA/cm2 150 min
U. Landau, Extended Astract, ECS
Meeting, Hawaii, October 1993
Periodic Reverse Plating for Effective Leveling
Deposit thickness:
DC Plating : - 0.5 V ~ 300 mA/cm2
11 x 10 min
Periodic reverse :
Plate: - 0.4 V ~ 300 mA/cm2 20 min
Dissolve: 1 V ~ 800 mA/cm2 0.2 min
U. Landau, Extended Astract, ECS
Meeting, Hawaii, October 1993
Periodic Reverse Plating for Effective Leveling
Deposit thickness:
K = 0.1 S/cm
T = 25C
I0 = 1 mA/cm2
aA = 1.8
aC = 0.2
DC Plating : 73 mA
3200 min
Periodic Reverse :
Plate: - 73 mA 1000 min
1.5 cm
Dissolve: 887 mA 887 min
Total process time: 5180 min
1 cm
U. Landau, Extended Astract, ECS
Meeting, Hawaii, October 1993
Double and Single sided Strip
Electro-galvanizing
Including analysis of the bi-polar
effect
Double-sided Strip Electro-Galvanizing
Drawing: shown not to scale
V = 5V
V=0V
10 cm
100 cm
V = 5V
140 cm
Dual-Sided Strip Electro-Galvanizing
Drawing: not to scale
V = 5V
V=0V
V = 5V
Single-Sided Strip Electro-Galvanizing
Auxiliary electrode on top – removed
Very little current leakage to back
V=0V
V = 5V
Drawing: not to scale
Bi-Polar Effect in Double-sided Strip Electro-Galvanizing
I=0
V = 5V
Components of the CAD system Geometry
Operating conditions
V or I
Properties:
• Thermo
• Kinetics
• Transport
Solver
Current distribution
Deposit thickness
Potential distribution
Deposit growth
Deposit composition
Concentrations profile
Required Properties for Electrochem.
Modeling
• Thermodynamics
–
–
–
–
Standard potential(s) – E0
Number of electrons transferred in electrode reaction - n
Activities
Temperature dependence
• Kinetics
– Polarization curve [i = f (η)]
• Butler-Volmer parameters:
aF
F 

iio exp( a )exp(  a ) 
RT
RT 

Exchange current density – i0
Anodic and cathodic transfer coefficients – α, β
• Polynomial correlation
• Transport
–
–
–
–
–
–
Conductivity – κ [= f(C,T)]
Diffusivity – D (Concentrated solutions: Ki,j)
Transport number – t
Viscosity (μ), density (ρ)
Velocity field: v x,y
Temperature distribution
How is data conventionally generated?
• Special Equipment
– Cells to provide uniform:
• Current density
• Transport conditions
Use special cells, e.g.,
– Rotating disk electrode (RDE)
– Rotating Hemispherical electrode (RSE)
– Rotating concentric cylinders (RCE)
– Reference electrode
– Potentiostat
– Data acquisition
• Specialized experimental procedures
– Current-voltage transients (scan, step, pulse...)
• Analysis (mechanistic, analytical…)
A Radically Different Approach -
Cell-Design’s ‘Expert System’ to “Reverse Engineer”
Geometry
Operating conditions
V or I
Properties:
• Thermo
• Kinetics
• Transport
Solver
Current distribution
Deposit thickness
Potential distribution
Deposit growth
Deposit composition
Concentrations profile
Expert System for Electrochemical
Properties
Use existing
measurements
(e.g., deposit
thickness) in
user’s system
Feed the data
into CellDesign
Get
system’s
electrochemical
properties
Use properties to:
• Design
• Optimize
• Trouble-shoot
Any system, same
chemistry
What is available?
• Hull-cell
– Appearance, but not at precise current density
– Does not account for different kinetics (type of metal)
– Does not account for transport
• ‘Hydrodynamically Modulated Hull-Cell’, ‘RotaHull’
– Curved (cylindrical) geometry – inconvenient observation
– Dependence of current distribution on Kinetics ?
– No precise measurements of current density or quantitative data
• To obtain kinetics constants
– Dynamic scan of polarization curve (Potentiostat, RDE,
Reference electrode)
©
L-Cell
(patent Pending)
• A test cell to characterize electrochemical processes
• Provides:
– Visual appearance of deposit at precisely measured range
of current densities (compare to Hull-Cell)
– Quantitative determination of:
•
•
•
•
•
•
•
Conductivity
Standard potential
Polarization curve
Kinetics parameters: i0, alpha, beta
Diffusivity or concentration
Current efficiency as function of current density
Electrochemical parameters of alloy systems
‘L- Cell’
(Pat. pending)
POLARIZATION CURVE
Copper deposition from acidified copper sulfate 0.24M
CURRENT DENSITY [mA/cm2]
160
THEORETICA
L
120
80
L-CELL
40
0
0.00
50.00
100.00
150.00
200.00
ACTIVATION OVERPOTENTIAL [mV]
250.00
300.00
POLARIZATION CURVE – TAFEL PLOT
Copper deposition from acidified copper sulfate 0.24M
2.5
Log i [mA/cm2]
2
1.5
THEORETICA
L
L-CELL
1
0.5
0
0.00
50.00
100.00
150.00
200.00
ACTIVATION OVERPOTENTIAL [mV]
250.00
300.00
‘L- Cell’ with Flow
‘L- Cell’ with Flow
N =
0.326
V = 11 cm/sec
0.267
0.227
0.198
0.177
0.165 mm
‘L- Cell’ with Flow
Acknowledgements
• CWRU
– Rohan Akolkar
• Applied Materials
– Yezdi Dordi
– Peter Hey
• L-Chem
– Alex Shepteban
– Andrew Lipin