deposition of thin lms - physics.muni.czdorian/schmidtova_depositions.pdf · vapour, oxygen or...

IntroductionApplications

PVDCVD

Deposition of thin films

Tereza Schmidtova

16th March 2011

Tereza Schmidtova Deposition of thin films


PVDCVD

I The act of applying a thin film to a surface is thin-filmdeposition - any technique for depositing a thin film ofmaterial onto a substrate or onto previously deposited layers.

I ”Thin” is a relative term, but most deposition techniquescontrol layer thickness within a few tens of nanometres.Molecular beam epitaxy allows a single layer of atoms to bedeposited at a time.



PVDCVD

Optical appl.Microelectronics appl.Biomedical appl.Automotive industryOthers

I Mirrors (metal-coated in first century AD); nowadays - Au, Alwith additives as Tin(II) chloride and others; one/two-waymirrors, semitransparent, ...

I Anti-reflective coatings (glasses, telescopes, lenses, ...);complex thin film structures with alternating layers ofcontrasting refractive index (destructive interference); oftenadditional coating repelling water and grease

I interference layers, polarization layers, ...

I in general any transparent layer



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PVDCVD


I transistors, diodes, capacitor, inductors, resistors andconductors and isolators in general

I CMOS (Complementary Metal-Oxide-Semiconductors)

I MOSFET (Metal-Oxide-Semiconductor field-effect transistors)

I Integrated circuit

I GaAs/Si growth on Si/GaAs, dopants B or P

I oxides - SiO2 or nitride - Si3N4



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MOS and MOSFET



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I implants (hip or other joints replacements)

I adsorb bandages or yarns, stitches

I needles, scalpels, tools in general

I wires, stents

I eye lenses

I pills

I polymer tubes (IV tube, ...)



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Medicine (hip replacement)



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Medicine (stents)



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I Surface modification: passivation, tribologicalappl., decorative appl., hydrophobic/hydrophilicappl.

I Microelectronics: passive (dielectric, resistor,capacitor, conductor, ... films), active (thin-filmtransistors, diodes), interconnections, integratedciscuits

I Anti-corrosive layers

I Optics: anti-reflection, reflection, intereference,polarization, ...

I Sensors: pressure, acceleration, gas, ...

I basic hard layers improving liveability of partincluding the engine



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I Photovoltaic cells

I Thin-film batteries

I Sensors (pressure, gas - toxins, heavy metals, acceleration)

I Tool manufacturing and coating

I wrappings



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Photovoltaics



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Thin film batteries



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Sensors



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Cutting tools (Tribological appl.)



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Coated Al foils, wrapping foils, bottles



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Vacuum EvaporationCathodic Arc DepositionElectron beam physical vapour depositionPulsed laser depositionSputter depositionSpraying

Vacuum Evaporation

I reduction of pressure in liquid-filledcontainer → liquid evaporation atlower temperature than normal

I history - process invented by HenriNestle in 1866 (condensed milk -water evaporation)

I as deposition technique forsemiconductor, microelectronicsand optical industry



PVDCVD


I evaporation by flash, arc (high contamination), laser ablation(clean), exploding wire (only metal films, clean), electron gun(SiO2)

I can be used in reactive mode (oxides)

Advantages and Disadvantages

I higher deposition rate than CVD or sputtering

I evaporation has Maxwellian energy distribution given bysource temperature, sputtering uses plasma (high-speed atoms- non Maxwellian distribution)

Application

I aluminized PET film, other packing - isolation from watervapour, oxygen or light - often transparent (thin is cheaperthan thick opaque)

I metal filmsTereza Schmidtova Deposition of thin films


PVDCVD


MBE - Molecular Beam Epitaxy

I low deposition rate (1 µm per hour); monolayer film

I Knudsen cells (heated to different temperatures)

I other configurations (ALE - Atomic Line Epitaxy, CBE -Chemical Beam Epitaxy, HWE - Hot wall epitaxy, LPE -Liquid Phase Epitaxy



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a) MOCVD, b) MBE c) CBE



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Cathodic Arc Deposition or Arc-PVD

I electric arc → vaporization of cathode target material →condensation on a substrate = formation of thin film

I technology origin in Soviet Union around 1960-1970

I strike of high current, low voltage gives rise to a small”cathode spot” (highly energetic emitting area), localizedtemperature around 15000◦C → high velocity (10 km/s) jetof vapourised cathode material

I presence of electromagnetic field influence the arc to rapidlymove over entire cathode surface

I arc is extremely dense, high level of ionization, clusters evenmacro-particles or droplets

I can be used in reactive mode



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PVDCVD


DisadvantagesI cathode spot stays too long → macro-particles or droplets are

poorly adherent, distort the coatingsI worse case - cathode material has low melting point (Al),

cathode spot can evaporate through target to baking plate orinto the cooling system

I to prevent this the magnetic field is widely used, even forcylindrical configuration the cathode rotates

I some companies also use filtered arcs that use magnetic fieldsto separate the droplets from the coating flux

Advantages - fast, highly dependableApplications

I cutting tools, hard films, nanocomposites (TiN, TiAlN, CrN,ZrN, AlCrTiN, TiAlSiN)

I DLC; filtering of macro-particles required, high percetengae ofsp3 bonds



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Electron beam physical vapour deposition - EBPVD

I target anode is bombarded with an electron beam (chargedtungsten filament under high vacuum) → electron beamcauses atoms from the target to transform into gaseous phase→ atoms precipitates into solid form on every surface

I high deposition rate (0.1 µm to 100 µm per minute) atrelatively low substrate temperatures



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Ion beam assisted deposition



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Disadvantages

I simple geometries, coating is line-of-sight (rotation andtranslation of the shaft helps)

I non-uniform evaporation rate as a result in filamentdegradation in electron gun

Advantages

I accessible low and high deposition rates, high materialutilization efficiency

I possible structural and morphological control of films

Application - hard coatings (cutting tools), electronic and opticalfilms



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Pulsed laser deposition - PLD

I high power pulsed laser beam is focused to strike the targetmaterial → target material is vapourised and deposited onsubstrate

I 1965 Smith and Turner utilized ruby laser for thin filmdeposition

I reactive mode possible

I energy is converted to electronic excitation and then intothermal, chemical and mechanical energy resulting inevaporation, ablation, plasma formation and even exfoliation

I ejected species contain also clusters, molten globules, ...

I penetration depth of laser beam 10 nm for most materials(type of material and laser wavelenght)



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PVDCVD


Disadvantages

I resputtering of deposited film → decrease in deposition rate

Advantages

I versatility (changing distances, laser wavelength, ...)

I small target size

Application - SiO2, SiC, TiN, semiconductors, metallic systems,polymers, ferrroelectric materials, ...



PVDCVD


Sputter Deposition

I ejecting of target material towards the substrate (momentumtransfer)

I various geometry (diode, triode, planar, asymmetrical, ionbeam)

I reactive mode possible

I presence of magnetic field enhanced sputtering and can guidesputtered ion flux towards substrate - magnetron sputtering

I HIPIMS



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Thermal spraying; Plasma spraying

I metled or heated materials is sprayed onto surface

I coating precursor is heated by plasma/arc or combustion flame

I large area, high deposition rate, thick layers (metals, alloys,ceramics, plastics, composites)

I history 1910s (flame spraying, wire arc spraying); plasmaspraying 1970s



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PVDCVD

Chemical vapour deposition

I from atmospheric pressure to ultra-high CVD

I PECVD (MPCVD - microwave plasma, RPCVD - remoteplasma)

I uses chemical reactions

I electroplating

I ion plating



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PVDCVD

Advantages

I Large size deposition

I good covering of complex surface structures

Dissadvantages

I CVD - high temperature (not in PECVD)

I chemical byproducts (chemical waste)



PVDCVD

taken from [Bunshah,1994]



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References

R. F. Bunshah. Handbook of deposition technologies for films andcoatings: Science, Technology and Applications, 2nd, editionNoyesPublications, 1994, ISBN 0-8155-1337-2

en.wikipedia.orgwww.google.com



PVDCVD

Thank you for your attention!


deposition of thin lms - physics.muni.czdorian/schmidtova_depositions.pdf · vapour, oxygen or...

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