Ivc 2013-1
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Cermet coating deposition byDC reactive co-sputtering process
controlled by voltage
Cermet coating deposition by DCreactive co-sputtering processcontrolled by voltage
Beatriz Navarcorena, Julián Rodrigo, Gonzalo G. Fuentes,José A. García, Ramón Escobar, Carlos Prieto, José AngelSánchez, Eva Céspedes, J. M. Albella
IVC-19 2013 – September 9-13, Paris, FRANCE
1
Introduction2
Selective coating design3
Objective
Index
Selective coating design3
Deposition and characterization4
Conclusions5
1
Introduction2
Selective coating design3
Objective
Index
Selective coating design3
Deposition and characterization4
Conclusions5
� To develop a solar selectivecoating for the parabolic trough solar
collectors that allows the operating temperature
Objective
collectors that allows the operating temperatureof the transfer fluid to reach 600ºC, and todevelop an application method for them (PVD).
1
Introduction2
Selective coating design3
Objective
Index
Selective coating design3
Deposition and characterization4
Conclusions5
Parabolic trough solar collectorParabolic trough solar collector
Introduction
Parabolic mirrorParabolic mirror Absorber tubeAbsorber tube
Key component: Absorber tubeKey component: Absorber tube
Introduction
AR-coated glass tube(high solar transmittance)
AR-coated glass tube(high solar transmittance)
Selective absorber coating(high solar absorptance and low
thermal emittance)
Selective absorber coating(high solar absorptance and low
thermal emittance)
Vacuum Insulation(minimized heat convection
losses)
Vacuum Insulation(minimized heat convection
losses)
Glass-to-metal sealGlass-to-metal seal
Introduction
↑ Solar absorptance ↓ Thermal emissivity
1,44 µm
1
Introduction2
Selective coating design3
Objective
Index
Selective coating design3
Deposition and characterization4
Conclusions5
LMVF cermet absorbing layer
Anti-reflection coating
Literature reviewLiterature review
Selective coating design
Substrate
IR-reflective metal
LMVF cermet absorbing layer
HMVF cermet absorbing layer
SiO2:Mo (LMVF)
SiO2
Our stackOur stack
Selective coating design
Stainless steel
IR-reflective metal (Ag)
SiO2:Mo (LMVF)
SiO2:Mo (HMVF)
Software simulationsSoftware simulations
� Dependence with the metal volume fraction� Dependence with the metal volume fraction
To optimize the optical parametersTo optimize the optical parameters
Selective coating design
� Dependence with the cermet thickness� Dependence with the cermet thickness
SiO2 64 nm
LMVF-20% 70 nm
HMVF-40% 113 nm
Ag
1
Introduction2
Selective coating design3
Objective
Index
Selective coating design3
Deposition and characterization4
Conclusions5
Selective coating deposition
Elemental targets: Al, Ti, Si, etc.
Reactive gases: O2, N2, etc.
DC-Reactive Magnetron SputteringDC-Reactive Magnetron Sputtering
Inert gases: Ar, etc.
HYSTERESIS EFFECT
SiO2, Al2O3, Si3N2…
Selective coating deposition
The hysteresis effectThe hysteresis effect
Metallic mode
Constant power
Voltage
Reactive gas flow rate
Reactive mode
Selective coating deposition
Increasing the pumping speed
Increasing the target-to–substrate distance
Control Methods
The hysteresis effectThe hysteresis effect
Increasing the target-to–substrate distance
Obstructing reactive gas flow to the cathode
Pulsed reactive gas flow
Plasma emission monitoring
Voltage control
I.Safi “Recent aspects concerning DC reactive magnetron sputtering of thin films: a review” Surface andCoatings Technology 127 (2000) 203-219
The hysteresis effectThe hysteresis effect
Selective coating deposition
Stoichiometry
K.Koski et al. “Voltage controlled reactive sputerring process for aluminium oxide thin films” Thin SolidFilms 326 (1998) 189-193
The hysteresis effectThe hysteresis effect
Selective coating depositionposition
Deposition rate
K.Koski et al. “Voltage controlled reactive sputerring process for aluminium oxide thin films” Thin SolidFilms 326 (1998) 189-193
Selective coating deposition
Control method used
speedflo™ Mini is a multi-
The hysteresis effectThe hysteresis effect
speedflo™ Mini is a multi-channel closed-loop controlsystem for high speedadjustment of a reactive gas formagnetron sputter processes.
Selective coating deposition
The hysteresis effectThe hysteresis effect loop point of maximal deposition rate
SiO2
Power Si constant = 2000 W
Selective coating deposition
Characterization by FTIR: SiO2Characterization by FTIR: SiO2
Selective coating deposition
The hysteresis effectThe hysteresis effect
SiO2:Mo
In co-Sputtering, the hysteresis loop of Si targetchanges when the Mo target is on
Selective coating deposition
Silicon power
(W)
Molybdenum power
(W)
Deposition rate
(nm/min)
1000
1000 23
3000 60
4000 97
2000
1000 45
2000 62
3000 83
4000 111
Selective coating deposition
Characterization by ellipsometryCharacterization by ellipsometry
Si(1000W):Mo(4000W)
Selective coating deposition
Optical simulations with real optical valuesOptical simulations with real optical values
Selective coating deposition
Silicon power
(W)
Molybdenum power
(W)
Deposition rate
(nm/min)
1000
1000 23
3000 60
4000 97
2000
1000 45
2000 62
3000 83
4000 111
HMVF
LMVF
Selective coating deposition
Layer Material MVF Thickness (nm)
IR mirror Ag - 250IR mirror Ag - 250
HMVF cermet Mo/ SiO2 0.28 100
LMVF cermet Mo/ SiO2 0.1 90
AR layer SiO2 - 50
Optical characterization of the stack
UV-Vis-NIR Spectrophotometer
Range: 200 nm – 3.3 mm
FTIR dual MIR/NIR Spectrometer
Rango: NIR: 11000-3000 cm-1 (0.9 - 3.3 µm)
MIR: 4000-400 cm-1 (2.5 – 25 µm)
Optical characterization of the stack
Sample Up-scaled
Temperature αααα2 εεεε2
RT 0,804 0,001
300 °°°°C 0,804 0,025
400 °°°°C 0,804 0,047
500 °°°°C 0,804 0,076
600 °°°°C 0,804 0,111
650 °°°°C 0,804 0,130
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1
Introduction2
Selective coating design3
Objective
Index
Selective coating design3
Deposition and characterization4
Conclusions5
Conclusions
DC-reactive sputtering technique has important advantages fordepositing multipurpose oxide films controlled by voltage.
DC-reactive Magnetron process requires fast control methods in orderDC-reactive Magnetron process requires fast control methods in orderto obtain high deposition rates with the desired stoichiometry, andwith a low reactive gas flow rate.
High value CSP technology stack architecture can be achieved by co-sputtering with a previous optical simulation.
Acknowledgments
The research leading to these results hasreceived funding from the European Community'sSeventh Framework Programme.
Thanks for your attention!