Combined Spectroscopic Ellipsometry and Ion Beam Surface Analysis for In-Situ Real-Time Characterization of Complex Oxid
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the YBCO thin film [1,2] at a photon energy of around 4.1eV, and that both in- and outdiffusion may be observed in real time by SE [3]. Furthermore, it has been shown that surface composition and structure of thin films may be measured by low energy (5-15 keV) ion scattering and recoil spectrometry with a time-of-flight detection scheme (TOF-ISARS) [4,5]. A pulsed probe ion beam with no more than 200,000 ions/mm2/pulse ensures negligible damage to the film's exposed surface, rendering this an ideal in-situ diagnostic technique for thin film growth. Combining pulsed beam operation with differentially pumped ion beam and detection optics, enables both in-situ and real time operation, i.e. during film growth and annealing. In order to be able to observe film growth dynamics, film composition and structure, in-situ and in real time, a sputter ion thin-film deposition chamber combining SE and TOF-ISARS for growth process measurement and control has been built. To demonstrate this unique system configuration, the combination of ion scattering/recoil spectrometry and ellipsometry has been used on thin films such as YBa 2Cu 307-8 on MgO, and a device structure electrode of Iridium on Titanium Nitride.
15 Mat. Res. Soc. Symp. Proc. Vol. 569 ©1999 Materials Research Society
EXPERIMENTAL Instrumental Details Deposition System The thin film deposition is accomplished by reactive ion sputtering using Ar+ ions generated by a 3cm Kauffman RF ion source with plasma bridge neutralizer. The ion beam is incident upon a rotating 4-in. diameter target made of the depositing material. The substrate wafer is secured to a heater, which is mounted to a rotatable X-Y-Z manipulator stage located above and behind the ion source (Fig 1). UWtiTN8d Amernbly
YBCO/MgO films were grown at 7000C at a deposition rate of -nm/min
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to a thickness of-550A using a stoichiometric YBCO target sputtered in a lx 10-4 torr 02 background pressure. The crystallographic orientation of the YBCO films grown on oriented MgO was
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checked with X-ray diffraction (XRD) and shown to be c-axis oriented. The
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quality of the YBCO was assessed by monitoring the disappearance of the 4.1 eV absorption peak using SE. This peak is sensitive to oxygen [1,2] and the peak intensity has been correlated to the superconducting transition temperature T,. Figure 1 Deposition System
Analysis System
In-situ measurements are made during film growth using SE and TOF-ISARS. A commercially available J.A. Woollam Inc.
configuration to allow
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multichannel ellipsometer with a photon range from 1.5 to 4.5 eV (Fig. 2 a, b) is mounted in a
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Telefocus
MsRDo f) DRS Detector Tub Ion Gun
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a) Ellipsometer Input
simultaneous acquisition of ion
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scattering spectra at 200 incidence,
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as measured from the surface normal, using a 25mm diameter ElFigure 2 Analysis system geometry Mul MSP-DT electrostatic dete
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