Area-selective Ru ALD by aC modification using H plasma ...€¦ · PUBLIC Ivan Zyulkova,b,...
Transcript of Area-selective Ru ALD by aC modification using H plasma ...€¦ · PUBLIC Ivan Zyulkova,b,...
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PUBLIC
Ivan Zyulkova,b, Ekaterina Voroninac,d, Mikhail Krishtaba,b, Dmitry Voloshind, BT Chanb, Yuriy Mankelevichd,
Tatyana Rakhimovad, Silvia Arminib and Stefan De Gendta,b
Area-selective Ru ALD by aC modification using H plasma:
from atomistic modelling to sub 50 nm patterned structures
a KU Leuven, Department of Chemistry, Faculty of Science, B-3001 Leuven, Belgium.b Imec, Kapeldreef 75, B-3001 Leuven, Belgium.c Lomonosov Moscow State University, Faculty of Physics, Leninskie Gory, GSP-1, Moscow 119991, Russian Federation.d Lomonosov Moscow State University, Skobeltsyn Institute of Nuclear Physics, Leninskie gory, GSP-1, Moscow 119991, Russian Federation.
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Briggs, Basoene, Ivan Zyulkov, and Katia Devriendt, "Method of patterning target layer."
U.S. Patent Application No. 15/975,611.
Advanced patterning- tone-inversion
Sacrificial
material
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PVD Cu deposition without (left) and with (right) Ru liner Ishizaka, Tadahiro, et al., Microelectronic Engineering 92 (2012): 76-78
3-dimensional model for low-pressure chemical vapor deposition step coverage in trenches and circular vias, M. Islamraja, et al., J. Appl. Phys., Volume 70, 1991, 7137
Filling of narrow structures
▪ Bottom-up metal deposition can be used for defect-free fill
▪ BU requires selectivity to the trench bottom vs sidewall material
Conventional top-down depositionBottom-up deposition
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Amorphous carbon film –ALD inhibitor Amorphous carbon (aC) film
Ru
aC
SiCN
10 seconds H2 plasma pre-treatment:
ELD Cu
Zyulkov Ivan, et al., Joint EuroCVD 21 – Baltic ALD 15
Conference Linköping, Sweden, 11 – 14 June, 2017.
Robertson, J. "Material science and
engineering." R 37 (2002): 129.
• Amorphous carbon films are commonly used as pattern transfer layers
sp2/ sp3 hydrogenated carbon
• Amorphous carbon can be used as a sacrificial dielectric for low-k replacement
L. Zhang, J. F. De Marneffe, N. Heylen, G. Murdoch, Z. Tokei, J.
Boemmels, S. De Gendt, M. R. Baklanov, Appl. Phys. Lett. 2015,
092901.
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Intrinsic selectivity aC vs SiCN/ low-k
aC
SiCN/ low-k
aC
SiCN/ low-k
H2 plasma pre-treatment
+
ambient
SiOx surface, hydrophilic
Hydrophobic surface,
CH2/CH3 passivation
Zyulkov, Ivan, et al. "Selective Ru ALD as a catalyst for sub-seven-
nanometer bottom-up metal interconnects." ACS applied materials &
interfaces 9.36 (2017): 31031-31041.
Non-growth area
Growth area
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ASD ALD Ru IMEC 10 seconds H2 plasma pre-treatment:
Zyulkov Ivan, et al., Joint EuroCVD 21 – Baltic
ALD 15 Conference Linköping, Sweden, 11 –
14 June, 2017.
ALD Ru
H2 plasma results in ALD Ru inhibition on aC vs SiCN
Downsides:
• ALD Ru defectivity
• aC etch (50 nm / min)
aC
SiCN
aC
SiCN
aC
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ASD ALD Ru IMEC 10 seconds H2 plasma pre-treatment:
Zyulkov Ivan, et al., Joint EuroCVD 21 – Baltic
ALD 15 Conference Linköping, Sweden, 11 –
14 June, 2017.
ALD Ru
H2 plasma results in ALD Ru inhibition on aC vs SiCN
Master-plan:
N-free etch of aC
aC pre-
treatment by
H radicals
ASD
ALD of Ru
MD
modeling of
aC
modification
in H2 plasma
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Remote He/H2 etch of aC (hydrogen radicals only)
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SE measurements of aC etch
• The etch rate is close to zero @ 65
• Clear etch rate increase is observed with the etch
process temperature increase, which indicates C-C
bonds breaking
• Activation energy ~ 28.4 kJ/mol
• Etch is performed in He/H2 plasma
2000 W
• Only radials can reach the sample
surface due to the tool
configuration (downstream plasma
source)
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Remote He/H2 etch of aC (hydrogen radicals only)
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Pristine aC WCA is 67.5 ± 1.6 degrees
WCA measurements of aC etch
• Significant modification of aC @ low plasma temperature (65 ºC), no etch, carbon reduction
• Hight process temperature – aC etch, dangling bonds formation, impurities for the chamber sidewalls
XPS C1s
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ALD Ru at 250 C
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RBS Ru areal density• Clear benefit in ALD inhibition after cold
He/H2 plasma (H radicals only)
• To be tested on a patterned structure
Plasma T ºC decrease
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MD modeling of aC exposed to H ions
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Power,
W
Ne, cm-
3
Vrf Te,
eV
H flux, cm-2s-1 H3+ flux, cm-2s-1 H2
+ flux, cm-2s-
1
H+ flux, cm-
2s-1
150 1.3∙1010 180 2 1.8∙1016 1.5∙1015 3.1∙1014 1.5∙1014
300 2.7∙1010 270 1.6 2.6∙1016 2.5∙1015 5.7∙1014 3.3∙1014
Discharge parameters obtained in PIC MCC simulation- 300 mm CCP plasma reactor
(Particle‐in‐cell with Monte Carlo Collision)
Modeling of
the plasma
discharge
MD
modeling of
aC exposed
to H ions
MD
modeling of
aC exposed
to H radicals
• H radicals are the main species in H2 plasma
• Concentration of H3+ ions is 10 times lower in comparison with the concentration of H radicals
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MD modeling of aC exposed to H ions
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Ion energy distribution function
Mean energy of H ions:
300 W – ion energy of 120 eV
60 W – ion energy of 50 eV
• H radicals energy increases with the plasma power increase
• 300 W – H ion energy of 120 eV
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MD modeling of aC exposed to 120 eV H ions at different ion fluences
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• aC layer thickness increases by 3.2 nm, no etch is observed. Etch requires both: H ions and radicals
• H penetrates into aC film, C-C bonds scission
• Hydrogenation occurs in the bulk of aC
Starting ratio of sp/sp2/sp3 is 4/65/31
H ion fluences
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MD modeling of aC exposed to 120 eV H ions at different ion fluences
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a-C density before and after exposure to
H ions at the fluence of 3.2·1016 cm-2
• Hydrogenation occurs mainly in the bulk of the aC film
• The average density of H-modified a-C layer is ~1.4 g/cm3 (initial a-C density is 2.5 g/cm3)
Relative concentrations of C and H atoms
after exposure to H ions at the fluence of
3.2·1016 cm-2
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MD modeling of aC exposed to 120 eV H ions at different ion fluences
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sp sp2
sp3
• CH/CH2 groups are present in 80/20 proportion
• Most of CHx groups are inside of the film
Distribution of CHx groups
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300 W (120 eV) vs 60 W (50 eV)
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• Plasma power decrease results in lower H ion energy
• Low H ion energy results in surface-confined modifications of aC
H concentration
aC density
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MD modeling of aC exposed to H radicals
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MD modeling of aC exposed to H radicals
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• H radicals do not break C-C bonds, but they break C=C
• Surface hydrogenation and increase sp2 at the expense of sp
Carbon hybridization fractions before and after
exposure to H radicals
Relative concentrations of carbon and hydrogen in a-
C before and after exposure to H radicals
sp
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CONCLUSIONS
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Experiment
• Downstream He/H2 plasma (H radicals) at 65 ºC does not etch aC. H radicals provide surface
hydrogenation and hydrophibisation (WCA = 97º)
• Downstream He/H2 plasma treatment results in more than 500 cycles ALD inhibition (corresponds to ~
5 nm Ru on SiCN)
MD modeling
• H ions break C-C bonds. H ions combined with H radicals are needed to etch aC
• H radicals do not break C-C bonds at room temperature, however the can transform C=C bonds into
C-C bonds forming CHx groups
• Near-room temperature H radicals treatment (remote H2 plasma) is the best treatment for aC to
maximize the number of CHx groups and minimize layer damage
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PUBLIC