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Chamber for in-situ synchrotron radiation studies of Chamber for in-situ synchrotron radiation studies of thin films grown by reactive magnetron sputtering
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Reactive magnetron sputtering is a technique often applied to thin films deposition. The composition and structure of the final films depend on a number of physical andgeometrical parameters selected for the process. All these parameters are a priori defined, and normally maintained during the whole process. The features of the resultingfilms (crystalline and/or amorphous structure, distribution of stress across the film, texture, physical properties, etc.) depend on the specific parameters selected for thefilms (crystalline and/or amorphous structure, distribution of stress across the film, texture, physical properties, etc.) depend on the specific parameters selected for theparticular deposition process. The structure can vary during film development, this variation not necessarily being reflected on the profile cross section of the film in its finalstate. This often occurs because the new developed layers can induce structural modifications to the preceding ones. For this reason it is worth to study the kinetic of filmgrowth –by using for example in-situ X-ray scattering techniques– along the whole deposition process. Because of this we have designed and constructed a chamber forgrowth –by using for example in-situ X-ray scattering techniques– along the whole deposition process. Because of this we have designed and constructed a chamber forpreparing thin films by reactive magnetron sputtering that allows for simultaneous X-ray scattering measurements.
������� ����� ����������The chamber was designed for working under vacuum (base pressure down to 10-6
Torr). It has two Kapton windows allowing for the entrance of the incident
����� ���Aluminum nitride, which is a III-V family compound, has the structure ofhexagonal würtzite. As it features a wide bandgap, high electrical resistivity, highTorr). It has two Kapton windows allowing for the entrance of the incident
synchrotron X-ray beam and the exit of the X-ray photons scattered by the growingthin film. The chamber will be mounted on the Huber 5 axes diffractometer of theXRD2 LNLS beam line. The setup allows for varying the incidence and tilting
hexagonal würtzite. As it features a wide bandgap, high electrical resistivity, highresistance to breakdown voltage, a high acoustic propagation rate and a lowtransmission loss, AlN film has a wide application potential in microelectronicdevices, especially in surface acoustic wave (SAW) devices [3].XRD2 LNLS beam line. The setup allows for varying the incidence and tilting
angles, the tilting being controlled by an internal motor. The 2-theta exit angleranges from -2o up to 70o. Our design will allow for a continuous study of thin filmsduring their growth by X-ray diffraction (XRD) and X-ray reflectometry (XRR).
The performance of an AlN film is greatly influenced by its microstructure, which isstrongly affected by deposition conditions. For example, films with variouspreferred orientations will show different piezoelectric behavior: (002) preferred
devices, especially in surface acoustic wave (SAW) devices [3].
Incident X-rays Diffracted X-rays
Magnetron
during their growth by X-ray diffraction (XRD) and X-ray reflectometry (XRR). preferred orientations will show different piezoelectric behavior: (002) preferredorientation is shown to be better. The heat dissipation capacity of AlN films isgoverned by such microstructure factors as morphology, interface roughness andpreferred orientation [4].
EXPERIMENTALAlN films were deposited with a 99.99% pure Al target and in 99.9995% puritynitrogen and argon mixture of ¼ N and ¾ Ar on Si(100) and Si(111) substrates.
Magnetron
Incident X-rays Diffracted X-rays preferred orientation [4].
Magnetron
nitrogen and argon mixture of ¼ N2 and ¾ Ar on Si(100) and Si(111) substrates.DEPOSITION CONDITION:Substrate-to-target distance: 3 cm Residual pressure: 5.44·10-6 TorrPower density: 6.8 W/cm2 Sputtering pressure: 6.19 mTorr
Kapton windows�
Kaptonwindows
Observation
Pumping
Power density: 6.8 W/cm2 Sputtering pressure: 6.19 mTorrGas flow rate: 4 sccm Deposition time: 60 min
Sample
DRXObservation
window
Gas
Sample
Vacuumsensor
Incident X-rays
On Si(111)DRX
On Si(100)
Gas inlet Sample position
Incident X-rays Diffracted X-rays
A similar chamber was previously developed at LNLSand dedicated to in situ studies of steels during ionand dedicated to in situ studies of steels during ionnitriding processes. The use of this setup hasparticularly allowed us to clearly detect a rapidexpansion of the fcc austenitic structure of stainlessexpansion of the fcc austenitic structure of stainlesssteels thus giving rise to a new phase named asexpanded austenite [1,2].
Inte
nsity
(cps
)
Inte
nsity
(cps
)
Inte
nsity
Inte
nsity
Auger Electron Spectroscopy (AES) from an AlN filmobtained in this new chamber. Sputtering was made with 4
A X’Pert-XRD X-ray diffraction instrument with CuK� radiation was used for XRDmeasurements. Grazing incidence scan was used for phase identification.
obtained in this new chamber. Sputtering was made with 4keV Ar+. Electron beam was applied at 2 keV energy.
AcknowledgmentAuthors thank to the Consejo Nacional de Investigaciones Científicas yTécnicas, to the Instituto de Física de Rosario, to the Universidad Nacional
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de Rosario, and to Lic. Lucio Isola, Javier Cruceño, Horacio Merayo.
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