Atomic Layer Deposition Processes for Integration in...
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Atomic Layer Deposition Processes for Integration in ULSI Metallization Systems and Spintronic Sensor Devices Thomas Waechtler Fraunhofer Institute for Electronic Nano Systems ENAS & Center for Microtechnologies, TU Chemnitz Chemnitz, Germany Contact: [email protected]
Transcript of Atomic Layer Deposition Processes for Integration in...
Atomic Layer Deposition Processes for Integration in ULSI Metallization Systems and Spintronic Sensor Devices Thomas Waechtler Fraunhofer Institute for Electronic Nano Systems ENAS & Center for Microtechnologies, TU Chemnitz Chemnitz, Germany Contact: [email protected]
T. Waechtler
October 9, 2012
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Outline
• Overview – Fraunhofer Institute for Electronic
Nanosystems ENAS
• ALD @ Fraunhofer ENAS and ZfM Chemnitz
Equipments for ALD
ALD Process Integration for Interconnects
ALD Process Development for Magnetic / Spintronic Sensor
Systems
Integration of ALD with CNTs for Interconnects and NEMS
• Summary
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Headquarter: Chemnitz, Germany
140 employees, 13 Mio. € annual budget
International Offices:
Since 2001/2005 Tokyo/Sendai, Japan
Since 2002 Shanghai, China
Since 2007 Manaus, Brazil
Systems integration by using of micro and nano technologies
MEMS/NEMS design
Development of MEMS/NEMS
MEMS/NEMS test
System packaging/wafer bonding
Back-end of Line technologies for micro and nanoelectronics
Process and equipment simulation
Micro and nano reliability
Printed functionalities
Advanced system engineering
Fraunhofer Institute for Electronic Nano Systems
Close cooperation to TU Chemnitz – Center for Microtechnologies
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Headquarter: Chemnitz, Germany
140 employees, 13 Mio. € annual budget
International Offices:
Since 2001/2005 Tokyo/Sendai, Japan
Since 2002 Shanghai, China
Since 2007 Manaus, Brazil
Systems integration by using of micro and nano technologies
MEMS/NEMS design
Development of MEMS/NEMS
MEMS/NEMS test
System packaging/wafer bonding
Back-end of Line technologies for micro and nanoelectronics
Process and equipment simulation
Micro and nano reliability
Printed functionalities
Advanced system engineering
Fraunhofer Institute for Electronic Nano Systems
Close cooperation to TU Chemnitz – Center for Microtechnologies
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Working areas ALD @ Fraunhofer ENAS and ZfM Chemnitz
Interconnects Spintronics 3D nanostructures
Cap
SiO2 or ULK
Barrier PVD Seed
ECD Cu
• ALD Cu seed layers for ULSI interconnects
• Development of ALD processes for liner deposition (e. g. Ru, Co, Ni)
Substrate
Ferromagnet (e. g. Ni, Co) Non-magnetic conductor (Cu)
Ferromagnet (e. g. Ni, Co) Antiferromagnet (e. g. NiO)
Fig.: Typical GMR spin valve layer stack
• ALD utilization for spintronic devices, like GMR sensor systems
200 nm
200 nm
Ni substrate
ALD film (5 nm) on Ni
Fig.: SEM top view images
• Functionalization of 3D nanostructures by ALD coating with conformal layers or nanoparticles, e. g.:
CNTs Nanowires Porous materials
Pristine sample After CuxO ALD
550 ALD cycles
Fig.: SEM images of vertically aligned MWCNTs in via holes
400 nm
400 nm
Photo courtesy AMD Saxony / GLOBAL-FOUNDRIES Dresden
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Equipment
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Equipment I – 100 mm Single-Wafer Research Reactor ALD @ Fraunhofer ENAS and ZfM Chemnitz
(1) Load lock chamber
(2) Wafer transport chamber
(3) Reactor chamber
(4) Gas inlet
(5) Two bubbler systems (currently used for water and formic acid)
(6) Two liquid delivery systems (currently used for Cu and Ni precursors)
1
2
3
4 5 6 6
Cold wall reactor (substrates up to 100 mm diameter; smaller pieces on carrier wafer)
Process gases: Ar, H2, O2, NH3
Process temperature up to 400°C
Turbo + Roughing
Roots + Roughing
Base pressure < 3 x 10-6 mbar Processing pressure range: 0.1 to 10 mbar Typical processing pressure (copper oxide ALD): 0.5 to 1.5 mbar
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Equipment II – New 200 mm “Nanodeposition Cluster Tool” Strategic Investment Fraunhofer Microelectronics Alliance VµE
ALD @ Fraunhofer ENAS and ZfM Chemnitz
Cluster system • R&D and small series production • Ion-beam sputtering (IBSD) of
ultra-thin metals • (PE)CVD of carbon nanomaterials
(CNTs, graphene) • (PE)ALD of oxides, nitrides, and
metals in 2 ALD chambers • In situ analytics (Raman, XPS) • Industrial standard
(class 10 cleanroom) • 200 mm wafer size • Automatic handling
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Process Integration for ULSI Interconnects
Cap
SiO2 or ULK
Barrier PVD Seed
ECD Cu Photo courtesy AMD
Saxony / GLOBAL-FOUNDRIES Dresden
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• Cu(I) β-diketonate precursor
− Fluorine free – avoiding adhesion issues
− Liquid under standard conditions – liquid precursor delivery during ALD
• Oxidation by a mixture of water vapor and O2 (“wet O2“)
Precursor Pulse
Argon Purge
Oxidation Pulse
Argon Purge
ALD
cyc
les
1st step: Copper oxide ALD
2nd step: Vapor phase reduction
C
C
CH3
CH3
CH2
O
O
Cu
(CH3CH2CH2CH2)3P
(CH3CH2CH2CH2)3P
Process temperature < 140°C
Our Approach T. Waechtler, et al., J. Electrochem. Soc. 156, H453 (2009) T. Waechtler, et al., DE 10 2007 058 571, international patents pending
Well established process for CuxO ALD
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Reduction of the Copper Oxide Films Challenge: • Efficient reduction to metallic copper • On arbitrary substrates • In 3D nanostructures • Without agglomeration
Idea: Precursor mixture for in-situ doping the CuxO films with catalytic amounts of Ru to improve the reduction efficiency on arbitrary substrates
• Liquid under standard conditions
• Established synthesis route
• Mixable with the Cu precursor, typically 1 mol-%
• Stable within the CuxO ALD window (≈ 120 °C)
RuSi(CH3)3
Patent pending.
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ECD Experiments Cu ECD on Patterns with PVD Ru and PVD Ru / ALD Cu
Initial film stack: 10 nm PVD TaN / 10 nm PVD Ru
1 µm
SiO2
Si
ECD Cu
1 µm
SiO2
Si
ECD Cu
Initial film stack: 10 nm PVD TaN / 10 nm PVD Ru / ~ 8 nm ALD Cu
Unoptimized ECD conditions, comparable to the processes on blanket wafers
Grainy Cu, incomplete filling Denser Cu, better filling behavior
ECD Cu
PVD Ru 10 nm
PVD TaN 10 nm
Patterned SiO2
Si
ECD Cu
PVD Ru 10 nm
PVD TaN 10 nm
Patterned SiO2
Si
ALD Cu ca. 7 nm
T. Waechtler, et al., Microelectron. Eng. 88, 684 (2011)
Combination Ru/ALD Cu could enable nanoscale interconnect metallization
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Process Integration for Spintronic Sensor Devices
Substrate
Ferromagnet (e. g. Ni, Co) Non-magnetic conductor (Cu)
Ferromagnet (e. g. Ni, Co) Antiferromagnet (e. g. NiO)
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Process Integration for Spintronic Sensor Devices Integration of the ALD CuxO / Cu Process with Magnetic Thin Films
200 nm
CuxO ALD film on Ni
Ni
• Smooth and continuous CuxO ALD films on PVD Ni and PVD Co using precursor mixture
200 nm
CuxO ALD film on Co
Co
SEM top-view investigations
TEM cross section
• Growth behavior unchanged despite addition of Ru precursor
Si
20 nm SiO2
10 nm
10 nm
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Process Integration for Spintronic Sensor Devices Remote Hydrogen Plasma Reduction as Alternative Reduction Route
120 140 160 180 200 220 240 2602425262728293031323334
After CuxO ALD (8 nm) After reduction 5 min After reduction 10 min After reduction 20 min After reduction Ni substrate
Shee
t res
istan
ce [O
hm /
sq.]
Temperature [°C] 0 5 10 15 20 25 30 35 401
10
100
1000
Resi
stiv
ity [µΩ
*cm
]
Cu film thickness [nm]
ALD Cu Liu et al. - evaporating Jacob et al. - evaporating Vancea et al. - evaporating Walter et al. - sputtering
Bulk
Sheet resistance: • Significant reduction of the sheet resistance on Ni substrates • Resistivity of 5 nm Cu on Ni of 55 µΩcm comparable with PVD techniques
Remote H reduction promising for process integration with Ni as ferromagnetic film
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Interesting Magneto-Optical Properties with ALD Materials
Extension of the working field: ALD metals (Cu, Ni) for 3D nanostructured spintronic and magneto-optical devices
ALD copper oxide strongly influencing magneto-optical properties of ultrathin metallic nickel films
M. Fronk, G. Salvan & TW et al., Thin Solid Films, 520, 4741 (2012)
G. Salvan & TW, et al., Microelectron. Eng., submitted (2012)
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ALD/CNT Integration for Interconnects
and Sensor Systems
Pristine sample After CuxO ALD
550 ALD cycles 400 nm
400 nm
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ALD/CNT Integration for Interconnects and Sensor Systems Selective CNT Growth in Vias
• Decomposition of C2H4 catalytic Ni nano particles growth of MWCNTs
• Selective growth by interaction of catalysator and substrate
SEM investigations of CNTs selectively grown in vias
Schematic of CNT growth
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ALD/CNT Integration for Interconnects and Sensor Systems Overview of Results
• Pre-treatment with wet oxygent at 300°C leading to layer-like ALD growth
Possible damage of the regular carbon lattice of the outermost CNT shells
Layer-like growth reported on amorphous carbon
200°C H2O+O2 300°C O2 100°C H2O+O2 300°C H2O+O2
• In situ pre-treatment of CNTs applicable to tune ALD growth behavior • Deeper studies underway
M. Melzer & TW et al., Microelectron. Eng., submitted (2012)
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Summary
• Fraunhofer ENAS and ZfM Chemnitz – R&D for new materials and system integration for microelectronics and MEMS/NEMS
• ALD tools available for research and application up to 200 mm
• Thermal ALD and plasma-enhanced processes
• Standard oxides, metal nitrides, metals
• ALD development activities focusing on metals for
• ULSI interconnects
• Magnetic / spintronic sensor system
• Integration with 3D nanostructures such as CNTs for nanoelectronics and NEMS
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Acknowledgments
• Prof. H. Lang et al., TUC – precursor synthesis
• Prof. M. Albrecht et al., TUC – magnetic materials and systems
• Prof. D.R.T. Zahn, Prof. G. Salvan et al., TUC – magneto-optical Kerr spectroscopy
• BMBF “Nano System Integration Network of Excellence – nanett”, FKZ 03IS2011
• DFG International Graduate School IRTG 1215 “Materials and Concepts for Advanced Interconnects and Nanosystems”
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Thank you for your attention!
Visit us at booth # 2.108 (Hall 2, "Science Park")
Contact: Dr. Thomas Waechtler Fraunhofer ENAS, Chemnitz, Germany Tel.: +49 (0)371 45001-280 [email protected]
