Atomic Layer Deposition: An innovative approach for next ......Excellent conformality complex geometrical structure, aspect ratio up 1:10 000. Large Palette of available materials

Atomic Layer Deposition: An innovative

approach for next generation particle

accelerators

Thomas Proslier

15/06/2018

CMSDouble Chooz HESSEdelweiss HerschelALICE

Déchiffrer les rayons de l’Univers

IRFU/Service Page 2

Particle acceleratorsCERN ILC = 17 miles

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Atomic Layer Deposition (ALD)

ALD is a thin film synthesis technic based on sequential, self limiting surface chemical reactions between

precursor in the gas phase. It is a layer by layer deposition method.

Pros:

Control at the atomic level of thickness and chemicalcomposition

Films are smooth , continuous, and pinhole free on large surfaces

Excellent conformality complex geometrical structure, aspect ratio up 1:10 000.

Large Palette of available materials

Limits:

Slow growth ~ 1 Å/cy

New materials require new chemistries.

Al2O3 = TMA(Al(CH3)3) + H2O

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Systèmes de dépôts ALD

Cluster tool ~1 M€ Small ALD~ 75k€

Home made ~ 100-150 k€ Temperature ~ TA et 450-500°C

Pression ~ 1 mbar – laminar flow

Neutral gas N2 ou Ar

Précursors: solid, gas or liquid

Substrats: porous, powders, flats…

In-Situ Characterisation:

Thickness (quartz microbalance)

Gas analysis (mass spectrometer)

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In-situ Measurements – ALD Al2O3

Quartz Microbalance

Mass Spectrometry

Discret step growth

1 cycle = Quantum of ALD

Reaction product:

Méthane CH4

Séminaire IRFU – 14/06/2018

Al(OH)*x + Al(CH3)3 -> AlOxAl(CH3)*3-x + x CH4

AlOxAl(CH3)*3-x + 1,5 H2O -> AlO1,5Al(OH)*x + (3-x) CH4

Surface reactions x= 1,5

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ALD Al2O3

Séminaire IRFU – 14/06/2018

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ALD broad Palette of Materials

See: Miikulainen et al., J. Appl. Phys. 113, 021301 (2013).

Puurunen, J. Appl. Phys. 97, 121301 (2005).

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(LUMINEQ, Beneq Oy, Finland)

R.W. Johnson et al., Materials Today 17, 236 (2014).

ALD - Applications

Microelectronic (high κ thin films): HfO2, Ta2O5, La2O5, Al2O3

Photovoltaïc (Transparent Conducting Oxide): ZnO:Al, InSnO, PbS

Biomedical: TiN, ZrN, CrN, AlTiN

Photonic Crystals: ZnO, ZnS:Mn, TiO2, Ta2N5

Batteries: Al2O3, LaF3, SnF2…

Electroluminescence: SrS:Cu, ZnS:Mn, ZnS:Tb, SrS:Ce

Détectors (MCP’s, gases…)

Catalysis: Pt, Ir, Co, TiO2, V2O5

Thermoelectric: Bi2Se3, Bi2Te3…

Diffusion barrier/anti-corrosion: ZrO2, TiN…

Supraconductors: MoN, NbTiN, TiN…

LED: AlGaN/GaN

Electronique flexible Films diélectrique haut κ

Passivation OLED

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ALD – Applications – Structures

Coating ALD (ZnO) on porous structures: mitigation of charging + enhanced contrast

Electronic microscopy (TEM, SEM)

Tomography (synchrotron) Scientific reports, 7, 5879 (2017)

Self organisation (Block Copolymer)

Advanced Functional Materials, 22, 5129 (2010)

ALD

ALD

JVSTA, 36, 02D403 (2018)

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ALD – Applications – Supraconducteurs

MultiLayers: screening magnetic field for SRF cavities – increase current density JC

Bolometers:

Qubits & quantum computing:

- New superconducting alloys: Nitrides.

- New applications: quantum phase jump junctions,

charge interference junctions, cinetic

inductance…

- Thin superconducting films. Control Tc et de ΔTc

- Cosmological Background Radiation (CMB), dark matter

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Approach 1: Multilayers

A. Gurevich, APL 88, 012511

Fields in bulk Nb cavities approaching dc depairing limit for Nb, Hc(0) ≈ 200 mT

Superconductor-Insulator multilayer [Gurevich, Appl. Phys. Lett. 88, 012511 (2006)] Increase performance

– Move beyond limits of Nb Decrease cost

– Higher operating temperature (reduce cryogen costs)– Replace bulk Nb with cheaper material (Cu/Al)

Coat inside Nb SRF cavity with precise, layered structure → ALD

Séminaire LMGP-Grenoble 24/11/2016


ALD – Applications – Supraconducteurs

Niobium Carbide: NbC 1.7 K

Niobium Carbo-Nitride: NbC1-xNx 3.8 K

Niobium Silicide: NbSi 3.1 K

Titanium Nitride: TiN 3.9 K

Molybdenum Nitride: MoN 12 K

Niobium Titanium Nitride: Nb1-xTixN 14 K

NbSi - épaisseur

NbTixN - Composition

MoN - épaisseur

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MoNx ALD: Tc vs. thickness

Tc = 9.25 KΔNb = 1.55 meV

15nm

18 nm

20 nm

30 nm

60 nm

Thickness > 50 nm

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MoNx ALD: MoCl5 and NH3 – Epitaxy ?

Al2O3

MgO

MoN

TEM: C. Alvarez (ANL/NU)

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60 nm MoN

Klug, Becker, et al., Appl. Phys. Lett. 103, 211602 (2013).

Electrical Properties

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ALD on Nb cavity - superconductors

Deposition at temp. > 250°C for10 hr to 48 hr on Nb metal require an UHV environment

HV Oven : 10-8T a 500 0C

Automatic growth process

4 solid precuror lines HT (250°C)

1 precursor line UHT (500°C)

4 precursor lines gases/liquids

RGA analysis

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Eacc [MV/m]

NbTiN/AlN

ALD multilayer NbTiN(50 nm)/AlN(10 nm) 450°C – 10 hrs

ALD

ALD multilayer MoN(80 nm)/AlN(10 nm) 450°C – 10 hrs

1,00E+08

1,00E+09

1,00E+10

0 2 4 6 8

2…3…

Eacc [MV/m]

2 K

3.5K

MoN/AlN

ALD on Nb cavity - superconductors

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Approach 2: Doping + protection

Dissociate influences: doping vs. oxide

Gases:

- Nitrogen < 300°C et PN2 ~ 10-2 mbar

- oxide growth: O2, NO2, CO2

à T ~ 100-150°C et PX ~ 10-2 mbar

Other dopants (?)

- Layer deposition: NbN, TiN, MgO,

Al2O3, Y2O3 … thickness ~ 5 nm

- Annealing (diffuse O far into bulk butkeep metal cations within λ: Al, Mg, Y, Ti, …)

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ALD on Nb cavity: Dielectrics

10 nm Al2O3 (90°C – 1 hr) 2 nm Al2O3 / 15 nm Nb2O5(250°C – 2 hr)

15 nm Al2O3(250°C – 2 hr) + 450 °C/20 hrs

Remplace Nb2O5 by another more stable oxide: l’Al2O3

Diffusion/decomposition of Nb2O5 into bulk Nb to create a clean

interface.

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Hc2(0) → x(0) = 5.7 ± 0.1 nm

ALD applications for particle accelerators: Superconducting Magnets

Assume λ ~ 200 nm, estimate JD(0)~1×108 A/cm2; Jc(0) ~ 107 A/cm2

For MoN (d = 60 nm) on 50 µm Cu wire, IMAX ~ 1,5 A; IMAX(2K) ~ 1,3 A

H

𝑗𝑐 = 𝐻𝜋 𝑟

𝐿𝑛( 8 𝑟 𝑑 − 0.5)𝑤. 𝑑

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Copper magnet

Cu/MoN(1000cy)/AlN(300cy) at 450°C : 200 wires/ 50 µm diameter

Conformal Deposition

– Multilayer SIS

JC EXP ~ 10% de JD,

IMAX ~ 260 A per layer at 2 K

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ALD applications for particle accelerators: Superconducting Magnets


ALD Other applications for Particle accelerators

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3D printing + ALD: beamlines optics (Fresnell, kinoform Lenses and capillaries):

W ALD + PMMA

Charging of ceramics: mitigation by TiN thin film (2-5 nm) on ceramic windows (coupler)

Detectors (MCP’s): controlling resistivity by doping W:Al2O3 + high SEE layer MgO

Diffusion barriers or adhesive layers: Nb3Sn/Cu or Nb/Cu > 400°C – TiN/AlN on Cu.

Low secondary electron emission film ~ nm thick of carbide, nitrides…amorphous Carbon?


Where are we?

Laboratory set up (gases…).

ALD system: Setting up, Chemistry part is ready, Funding for Oven approved (85 k€) and ordered,

reception in 4 months. Missing: RGA, turbo pump + small dry pump + conn cavity – ALD.

ALD Doping: Oven for post-annealing up to 1200°C – qualified for cavity use.

Transport + Tunneling spectroscopy connected…proposal submitted for a Faraday cage (75 k€).

Magnetometry of C. Antoine working full speed. Upgrade to reach higher fields completed – 150 mT.

PANAMA: characterisation platform for particle accelerators.(SIMS, X-Ray). Need for better SIMS.

2 Nb cavities with good performance (Q = 1.5 1010 at 35 MV/m Quench at 37 MV/m) – EP ninja.

Missing: 1 more for doping.

Effort-Support: C. Antoine, Technician Aurelien Four + 1 PhD student. RF tests – cavity prep.

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Timetable-Deliverable

WP\T T1 T2 T3 T4 T5 T6

WP1-D1

WP2-D2

WP2-D3

WP2-D4

WP3-D5

WP3- D6

WP3-D7

WP1:

D1 – ALD system commissioning

WP2:

D2 – Deposition High Quality superconducting film on Nb samples

D3 – Optimization of screening efficiency on Nb samples

D4 – Deposition of optimized mutlilayers (MoN and NbTiN) on two Nb cavities

WP3:

D5 – Deposition of MgO, Y2O3 and Al2O3 films on Nb samples

D6 – Optimization of dopant concentration profile for MgO, Y2O3, Al2O3 films

D7 – Deposition of selected film and post annealing treatment on Nb cavity

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Budget

Items Description Cost (k€)

1 Niobium cavity 1.3 GHz Tesla Design 10

2 TOF-SIMS: Depth profile O + metal cations – 12 samples 6

3 ALD System oil pump (Neyco) 6

4 ALD System RGA 15

5 Adaptation flanges cavity – ALD system 3

6 ALD gas purifiers 4

7 Precursors 5

8 Shipping samples/cavity CERN – CEA 1

Total 50

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Partnership

Industry - ALD:

- CEA and AirLiquide Non-Disclosure Agreement (NDA) on new precursor synthesis

and 3D printing of Cu, Ti, Nb, Al pure metals.

- AirLiquide agreed to provide ~ 200 gr of new precursors of Nb, Mo and Mg.

-> first prove that ALD is working prior to more investment.

- Talk scheduled in September at AirLiquide

-> prepare for next round of AirLiquide internal funding decision

- CEA-Tech: Start up Incubator. + Paris-Saclay: IncubAlliance.

Collaborations:

CERN

- Transport, magnetometry,Tunneling spectroscopy for Nb/Cu or Nb3Sn/Nb and Nb3Sn/Cu

- Cavity tests …

DESY:

- Tunneling spectroscopy and X-Ray diffraction, SEM…

IPNO-LAL

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Direction de la Recherche Fondamentale

Institut de recherche

sur les lois fondamentales de l’Univers

Commissariat à l’énergie atomique et aux énergies alternatives

Centre de Saclay | 91191 Gif-sur-Yvette Cedex

Etablissement public à caractère industriel et commercial | R.C.S Paris B 775 685 019 Service

THANKS !


Summary - Epitaxy

High quality epitaxial IV-VI nitrides synthesized by atomic layer deposition at modest temperatures

(450°C).

Films on a-Al2O3 show superior electrical and superconducting properties compared to those grown

concurrently on amorphous SiO2.

Klug, Becker, et al., Appl. Phys. Lett. 103, 211602 (2013).

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Molybdenum nitride

d-MoN (P63mc) g-Mo2N (Fm3m)_

Crystal structures: Bull, et al., J. Solid State Chem. 177, 1488 (2004); Bull, et al., J. Solid State Chem. 179, 1762 (2006)

Tc = 12 K Tc = 5.2 K



Linear, well controlled growth with fine thickness control

Bulk-like density, roughness 25-35 Å

Growth temperature: 450 0C

MoCl5 + NH3 - AlN : AlCl3 + NH3

Molybdenum Nitride (MoN)



MoNx ALD: Tc vs. thickness



HALL MEASUREMENT

Carrier concentration

𝑘𝐹 = (3𝑛𝜋2) 1 3

𝑙 =𝑘𝐹 . ℏ

(𝑛 𝑒2 𝜌)

𝐷 = −4𝑘𝐵 𝑑𝑇𝑐 𝑑𝐻

𝜋 𝑒

𝜏 =𝑙2

3 𝐷

𝑚𝑒𝑓𝑓 = 𝑚𝑒

ℏ. 𝑘𝐹𝑉𝐹

𝑉𝐹 =𝑙

𝜏Dirty limit: ξ > l

Transition:

Strong disorder kF.l~1 to kF.l >> 1

meff = 6.4 me

MoNx ALD: Hall effect vs. Thickness



MoNx ALD : XPS - Composition vs. thickness

Composition: MoN 1:1 + Nucleation as Mo2N

Sputtering change stoichiometry from MoN to Mo2N



MoN (0001) Mo2N (111) Al2O3 (0001)

MoNx Density Functional Theory

MoN/Al2O3 Mo2N/Al2O3 MoN,int – Mo2N,int

m(N,NH3) @ 298K,0.1MPa m(N,NH3) @ 673K,0.1MPaDFT shows that: Mo2N is more favorable on C-Plan and MoN is preferred on R-Plan

Confirm the trend seen experimentally



Summary

Tune Tc and transport properties by controlling film thickness

Tune Tc and transport properties by controlling composition: Nb1-xTixN, TiN, MoN,

NbSi, NbC, NbCN ...

Growth temperature : lower Temp for High quality nitrides

Fundamental interest for Quasi 2D limits + applications: Bolometers, High

energy physics accelerators, magnets…

Future work: MgB2 (40K), FeSeTe (15K), K(FeSe)2 (31K) etc… More cavity

coating/Testing



Synchrotron tools

Synchrotron techniques offer a suite of probes sensitive to atomic-scale structural and chemical

information.

By applying synchrotron measurements in situ to study ALD processes, we can investigate the evolution of

crystallinity, microstructure, morphology, and chemical composition in the crucial early stages of film

growth.

ALDALD

Crystallinity

Microstructure

Morphology

Composition



MoNx ALD: Application ?

TiN(7.5 nm)/MoN(50nm) at 450°C

SQUID

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Nb1-xTixN: Superconducting Tc

Achieved superconducting Tc=14 K 4:1

– 40% higher than previously reported value for ALD NbN

[Hiltunen et al., Thin Solid Films 166, 149 (1988)]

Δ = 2.3 meV +- 0.1

T= 1.8K

50 nm NbTiN film

Atomic Layer Deposition: An innovative approach for next ......Excellent conformality complex geometrical structure, aspect ratio up 1:10 000. Large Palette of available materials

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