Fakultät Elektrotechnik und Informationstechnik Institut für Halbleiter- und Mikrosystemtechnik
Fundamental insight into ALD processing by in-situ observationsitu observation
Johann W. BarthaM Alb t M J i d M K tM. Albert , M. Junige and M. Knaut
Grenoble 8 10 2013Grenoble, 8.10.2013
Introduction of TU Dresden Institute for Introduction of TU Dresden, Institute for Semiconductors and Microsystemsand ALD applications (@ TUD IHM)
1. Atomic Layer Deposition (ALD) basics
2. Tools and setups, parameters and complexity
3. Process development (Precursor qualification)
- approaches (ex-situ, in-situ, in-situ 1 Cycle)
QCM- QCM
- SE
4 S4. Summary
IHM = Institut für Halbleiter- und Mik h ikMikrosystemtechnik
Semiconductor TechnologyProf Bartha
HLTHLTHLTHLT
Postal address:TU Dresden - IHM
OESMST&
PMSOES
MST&
PMS
Optoelectronic Systems
Prof LaknerMicro Systems Technology
Prof FischerPolymeric Micro Systems
Prof Richter01062 Dresden
+49 351 463 35292Fax: +49 351 463 37172
PMSNEM
PMSNEM
http://www.ihm.tu-dresden.deNanoelectronic Materials
Prof Mikolajick
400 sqm cleanroom class 10/100/1000
ALD films as …… gate stacks on MOSFET/CNT/SiNW… Cu diffusion barriers… ECD seed layers (HAR TSV)
moisture barriers (OPV OLED)… moisture barriers (OPV, OLED)…
ALD of Ta-based Adhesion Layers for CNT-Cu Matrix Composite Film GrowthC. Hossbach et al, Proc. MSR Spring Meet., San Francisco (US), 2007
Atomic layer deposition for high aspect ratio through silicon viasKnaut et al., Microelectronic Engineering, Volume 107, July 2013, Pages 80-83
One ALD Application at IHM: 3D TSV Technology
Model of a 3D TSV Transfer line on an interposer2 µm Cu
900 nm SiO2
5 nm TaN15 nm Ru
20,4 µmµm
Process flow at IHM:- Si deep etching
Thermal oxidation
189
µm
- Thermal oxidation- Conformal barrier and seed layer by ALD- Conformal Cu ECD- Generation of redistribution - Bumping
Introduction of TU Dresden Institute for Introduction of TU Dresden, Institute for Semiconductors and Microsystemsand ALD applications (@ TUD IHM)
1. Atomic Layer Deposition (ALD) basics
2. Tools and setups, parameters and complexity
3. Process development (Precursor qualification)
- approaches (ex-situ, in-situ, in-situ 1 Cycle)
QCM- QCM
- SE
4 Summary4. Summary
ATOMIC LAYER DEPOSITION
half-reaction A purge or evacuation
half reaction Bpurge or evacuation half-reaction Bpurge or evacuation
Self limiting growth behavior! Cyclic application!
ATOMIC LAYER DEPOSITION
half-reaction B purge or evacuation
half-reaction A purge or evacuation
ligand elimination, surface reactivation & film densification
metal-organic precursor adsorption (surface-controlled self-saturating & irreversible) & film densification
mou
nt
mou
nt
(surface controlled, self saturating & irreversible)
mou
nt
mou
nt
mat
eria
l am
mat
eria
l am
mat
eria
l am
mat
eria
l am
Ar purging timeexposure time of reactant B
Ar purging timeexposure timeof precursor A
V. Miikkulainen et al.: J. Appl. Phys. 113, 21301 (2013).
S. Elliott, and M. Shirazi: AVS 59th International Symposium & Exhibition (AVS, Tampa, 2012).
Introduction of TU Dresden Institute for Introduction of TU Dresden, Institute for Semiconductors and Microsystemsand ALD applications (@ TUD IHM)
1. Atomic Layer Deposition (ALD) basics
2. Tools and setups, parameters and complexity
3. Process development (Precursor qualification)
- approaches (ex-situ, in-situ, in-situ 1 Cycle)
QCM- QCM
- SE
4 S4. Summary
Impact of Process Parameters GPC
Important parameters for ALD process development:
- Substrate temperature defined by substrate, precursor,
ALD windowapplication or desired film properties
- Precursor and reactant doses as low as possible to save time and money
temperature
ALD window
GPCbut as high as needed for saturation
- Sufficient purge times to avoid CVD as short as possible to save time
GPC
- Gas flow optimization and pressure effects tool and application
d d t
precursor dose
surface saturated
GPCGPCdependent affecting process
parameters
GPC
ffi i t
purge time
purge sufficient ALD behavior
purge time
ALD TOOLS at IHM
5 ALD tools
8 ALD chambers
Up to 300 mm wafer size
In-situ RTP, Flash Lamps, …
In-situ methods and equipmentq p
300 mm ALD cluster tool (FHR Anlagenbau)
Handler chamber and load lock
Reaction chambers with direct in-situ analytics real time in situ measurements real-time in-situ measurements QCM, QMS, SE highly sensitive non-invasive
Connected Omicron UHV analytics tool in-vacuo measurements XPS, UPS, AFM, STM extremely sensitive no vacuum break no contamination
Introduction of TU Dresden Institute for Introduction of TU Dresden, Institute for Semiconductors and Microsystemsand ALD applications (@ TUD IHM)
1. Atomic Layer Deposition (ALD) basics
2. Tools and setups, parameters and complexity
3. Process development (Precursor qualification)
- approaches (ex-situ, in-situ, in-situ 1 Cycle)
QCM- QCM
- SE
4. Summary
Process Development GPC
(ex-situ film measurement)
temperature
ALD window
GPC
precursor dose
surface saturated
GPCGPC
Many Parameters
Folie 15 von 47purge sufficient ALD behavior
purge time
Many Parameters many deposition runs very time consuming!
Process developmentIn-situ using one sampleusing one cycleProcess development
film-thick-
Ex-situ method
In situ using one sample
film-thick-
In-situ 1-cycle method
using one cycle
ness ness
# of cycles time
GPCfilm-thick-ness
In-situ method
surface saturated ALD
Precursor Dose(Pulse time)# of cycles
Parameter
Quartz crystal microbalances - QCMQuartz crystal microbalances QCM
300 mm Cross-Flow Reactorwith heated chamber in chamberwith heated chamber in chamber
2 sensors (inlet + outlet)
Different crystal materials
≈V ∆f ≈ -∆m≈V ∆f ≈ -∆m
12“ wafer
P ibl h i i i l i f d d d lPossible approaches using in-situ analytics for advanced process development …
1. Approach - Automated precursor testing with short sub-processespp p g p
Comparable to standard process development with short sub-processes
but without wafer or sample loading/unloading, heat up, additional
measurement steps
Same data like using ex-situ measurements
Easy data acquisition and evaluation Easy data acquisition and evaluation
Higher reliability
P ibl h i i i l i f d d d lPossible approaches using in-situ analytics for advanced process development …
2. Approach - Analysis and comparison of single ALD cyclespp y p g y
pulse times for saturation impact extractable from every cycle
correlation between parameters and film growth mechanisms
evaluation more complex
prone to errors (drifts, noise, …)
fundamental understanding
TMA purge H2O purge
fundamental understanding
very fast method
1. Approach: 10 cycles per parameter set 2. Approach: Monitoring of single cycles
Growth per cycle TTIP adsorption
Fundamental insights: growth mechanisms and parameter impact on surface reactions
TiO2 ALD
from TTIP and H2O
1. TTIP chemisorption
2. Ar purging
3 i d l b O3. Ligand removal by H2O
4. Ar purging
1st half-reaction:
Process pressure affects
amount of chemisorbed TTIP
2nd half-reaction:
No process pressure p p
impact on ligand removal
In situ monitoring allows to understand non-uniformity issues by
comparing single ALD cycles at two QCM sensor positions
outlet
Outlet QCM sensor shows delayed film growth for higher process pressures
(triggered by inlet QCM sensor)
Reduced speed of process gasses Reduced speed of process gasses
Process development – applying Spectroscopic Ellipsometry
Measurement on the substrate!
M. Junige et al.: IEEE Semiconductor Conference Dresden(Dresden, 2011).
PROCESS PARAMETER (INTER)DEPENDENCIES
growth per cycle (Å/cycle)
1 0
Ru film thickness (nm)
successive sub-processes
0,0
0,5
1,0
ECPR pulsing (s)
0 5 10 15
0,5
1,0
0,0
0,5
0 5 10 15 20
O2 pulsing (s)
1 0
ALD cycle number0,0
0,5
1,0
deposition temperature
(°C)
ALD cycle number
M. Knaut et al.: J. Vac. Sci. Technol. A 30, 01A151 (2012).
M. Junige et al.: IEEE 2011 Semiconductor Conference Dresden (IEEE, Dresden, 2011).
150 250 350
irtSE: TA2O5 ALD (PULSEWISE RESOLUTION)
Ta2O5 optical layer thickness
in progression of 100 ALD cycles in the course of one ALD cycle
3,0
3,5
s (Å
)
1,5
2,0
2,5
ayer
thic
knes
s
TB
TE
MT
O3
0,5
1,0
optic
al la
0,00 60 120
time (s)
growth per cycle ≈ 0.6 Å at an actual deposition temperature of 215 °C
M. Junige et al.: DPG-Frühjahrstagung (DPG, Dresden, 2014).
irtSE: AL2O3 ALD (PULSEWISE RESOLUTION)
3 3
averaged optical layer thickness in the course of one Al2O3 ALD cycle at varied substrate set-point temperatures
3
ss (Å
)
500 °C400 °C300 °C
2
3
ss c
hang
e (Å
)
2
yer
thic
knes 200 °C
100 °C TMA0
1
3 4 5 6 7 8 9
thic
knes
time (s)
MA
1
optic
al la
y
-1
0
chan
ge (Å
)
( )
TM
A
O3
00 60 120 180
time (s)
O3-2
70 80 90 100
thic
knes
s
time (s)time (s) time (s)
M. Junige et al.: 8th Workshop Ellipsometry (AKE, Dresden, 2014).
irtSE: AL2O3 ALD (PULSEWISE RESOLUTION)
thickness increment per Al2O3 ALD cycle (left) and pulsewise thickness changes (right)at varied deposition temperatures
32
1
2
3
ss c
hang
e (Å
)2
r cy
cle
(Å) cummulative over 100 ALD cycles
cyclewise by averaging last 10 of 100 ALD cycles
per TMA exposure0
1
100 200 300 400
thic
knes
actual Si surf. temp. (°C) 1
crem
ent p
er
p ( )
thic
knes
s inc
-1
0
s cha
nge
(Å)
per O3 exposure0100 200 300 400
t
actual Si surface temperature (°C)
-2100 200 300 400
thic
knes
s
actual Si surf temp (°C)
M. Junige et al.: 8th Workshop Ellipsometry (AKE, Dresden, 2014).
actual Si surface temperature ( C) actual Si surf. temp. (°C)
IN-VACUO XPS: AL2O3 ALD
carbon XPS signal (in vacuo) at varied substrate set-point temperatures
carbon contamination and Al-to-O ratio in dependence on the deposition temperature
550%
u.)
C 1s
4
5
40%
50%
(at.%
)
ratio
50:50
40:60
nten
sity
(a. u 100 °C
200 °C
2
3
20%
30%
tam
inat
ion
m-t
o-ox
ygen
20 80
30:70
XPS
in 300 °C
400 °C1
2
10%
20%
carb
on c
ont
alum
inum
10:90
20:80
280285290295300
binding energy (eV)
500 °C00%
0 100 200 300 400 500
actual Si surface temperature (°C)binding energy (eV)
V. Sharma: Student Research Project (Technische Universität Dresden, Dresden, 2014).
actual Si surface temperature ( C)
irtSE: TANX ALD (PULSEWISE RESOLUTION)
averaged optical layer thickness in the course of one TaNx ALD cycle (left) and resp. details (right) at varied substrate set-point temperatures
2
3
4
ss c
hang
e (Å
)
4
s (Å
)
TBTEMT0
1
3 8 13
thic
knes
time (s)2
3
yer
thic
knes
s
400 °C
300 °C
250 °C ( )
-1
0
chan
ge (Å
)
TE
MT
3
1
optic
al la
y 200 °C
175 °C
150 °C
120 °C
NH3-3
-2
60 70 80 90
thic
knes
s
time (s)
TB
T
NH
3
00 60 120
time (s)
120 °C
time (s)time (s)
M. Junige et al.: 12th International Baltic ALD conference (Helsinki, 2014).
irtSE: TANX ALD (PULSEWISE RESOLUTION)
4
(Å)
thickness increment per TaNx ALD cycle (left) and pulsewise thickness changes (right)at varied deposition temperatures
2
3
4
knes
s cha
nge
per TBTEMT exposure1
2
100 150 200 250 300
thic
k
actual Si surf temp (°C)
-1
0
ss c
hang
e (Å
) actual Si surf. temp. ( C)
per NH3 exposure-3
-2
100 150 200 250 300
thic
knes
100 150 200 250 300actual Si surf. temp. (°C)
M. Junige et al.: 12th International Baltic ALD conference (Helsinki, 2014).
IN-VACUO XPS: TANX ALD
Nitrogen content Carbon and Oxygen concentration
Introduction of TU Dresden Institute for Introduction of TU Dresden, Institute for Semiconductors and Microsystemsand ALD applications (@ TUD IHM)
1. Atomic Layer Deposition (ALD) basics
2. Tools and setups, parameters and complexity
3. Process development (Precursor qualification)
- approaches (ex-situ, in-situ, in-situ 1 Cycle)
t t d t ti- automated testing
- advanced process development
4 S4. Summary
Summary
QCM and SE are capable to resolve
sub monolayer effectsy
This can be utilized to get information This can be utilized to get information
about the dynamics of the cycle
The GPC combines the effect of two
exposures and the dependency onexposures and the dependency on
process parameters need separately
to be understoodto be understood
Thank You!Spectroscopic Ellipsometer
Scanning Probe
Microscope
Quartz Crystal
Microbalance
X-ray / UVPhotoelectron Spectroscope pSpectroscope
XRD
4PP
QuadrupoleMass
Spectrometer
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