E. Zsoldos

Enhancement of oxidation resistance in Cu and Cu(Al) thin layers

High conductivity and good resistance to electromigration makes copper a promising interconnect material in microelectronics. However, one of its disadvantages is the poor corrosion resistance. Two methods of passivation are investigated and compared: Al alloying and BF a ion implantation. X-ray diAraction (XRD) and Rutherford Backscattering Spectrometry (RBS) show the oxidation inhibition of both methods, but the diAerent ratio of CuO2 to CuO phases suggests diAerent mechanisms of passivation. There are no definite oxide lines in the XRD spectrum of the implanted and annealed Cu(Al) sample, so the presence of Al and the implantation together give increased protection against oxidation. The diAerence between the two mechanisms of oxidation inhibition is discussed briefly. ” 1999 Published by Elsevier Science B.V. All rights reserved.

Epitaxy of orthorhombic gadolinium disilicide on 〈100〉 silicon

Epitaxial orthorhombic GdSi2 was grown by in situ vacuum annealing of a 50‐nm Gd layer on 〈100〉 silicon. The epitaxy was proved by x‐ray diffraction, electron diffraction, and ion channeling measurements. The lattice mismatch between the orthorhombic GdSi2 and 〈100〉 silicon substrate was found to be 4%.

Epitaxy of GdSi≊1.7 on 〈111〉Si by solid phase reaction

Epitaxial hexagonal GdSi≊1.7 was grown by in situ vacuum annealing of 50 and 250 nm Gd layers on 〈111〉 silicon. The epitaxy was investigated by x‐ray and electron diffraction measurements.

Formation of GdSi2 under UHV evaporation and in situ annealing

GdSi2 was prepared under ultrahigh vacuum conditions. Prior to processing, a clean interface was produced using diluted HF dipping. It is pointed out that the ‘‘critical temperature’’ for formation published earlier is probably an artifact and correlation between the interface native oxide and the critical temperature is established.

Effect of ion beam treatment on thermal annealing of GaAs-Au layer structures

Comparison of thermal annealing and ion mixing + thermal annealing on (100) GaAs-Au evaporated layers was made. The structures were investigated by SEM, X-ray diffraction, RBS + channeling and AES. Phase formation is retarded by ion implantation both for Ar and Xe, interdiffusion, however, is enhanced for Xe. Phases, as β-phase and GaAu2, were detected. An anomalous interdiffusion was found after low-dose Xe mixing, as gold penetration was deeper for 400°C post-annealing than for 500°C. Current-voltage characteristics of the diodes show that implantation procedure brings them nearer to ohmic behavior. Electrical measurements also point to a decrease of the number of defects as the annealing temperature increases up to 475°C in contrast to thermal annealing only [1].

The survivability of polycrystalline C60 to high speed vibration milling

Abstract For the solvent free mechanochemical synthesis of fullerene compounds as initiated by us in 1994, it became necessary to know how the polycrystalline C 60 structures resist to high speed vibration milling (HSVM). We have shown that there is no mechanical damage in the C 60 molecule up to a HSVM time of 30 min.

Kinetic pattern formation of Gd‐silicide films in lateral growth geometry

The solid phase reaction of gadolinium thin film and silicon substrate was investigated in lateral growth geometry with the help of periodic titanium protective stripes by optical microscopy. In the lateral reaction zone the shape of the interface between gadolinium and Gd silicide was very complicated and showed pattern formation. This silicide growth can be described as a kinetic process modified by the structure of the Gd film in contrast to the previously proposed simple nucleation.

Strain distribution in As+ and Sb+ ion implanted and annealed 〈100〉 Si

Abstract Si 〈100〉 wafers were implanted with a dose of 4×10 15 cm −2 with 40 keV and 72 keV As + and Sb + , respectively. Samples were isochronally annealed at 600, 700 and 800°C for 30 min. Characterization of the samples was made by double crystal X-ray diffractometry (DCD) and cross-sectional transmission electron microscopy (XTEM). Lattice strain depth profiles were determined from simulation of the X-ray rocking curves by a semikinematical model and were compared to XTEM observations. For arsenic it was found that the well-known positive strain arising from the dislocation loops at the earlier amorphous/crystalline interface increased with increasing annealing temperature. No significant change was found for antimony. The effect of larger ion size of Sb is confirmed by a positively strained layer at about half the depth of the regrown layer with roughly the same distribution as the distribution of the implanted antimony. In case of As, only a very small strain was observed at about the depth of the impurity concentration maximum. The strain distributions obtained from the rocking curve analysis were in good agreement with the XTEM observations.

Regrowth of a thin InP surface covering layer in the Au/InP system during annealing

Au(100 nm)/InP(111) samples were annealed at 500 °C in a forming gas for 10 min. Au9In4 and AuIn2 phases formed during the heat treatment. Besides the formation of Au‐In phases, a thin (about 20 nm thick), polycrystalline, continuous InP layer was observed on the top of the sample.

Thermal behaviour of Au/AIIIBV samples controlled with mass spectrometer

Abstract Au/GaAs, Au/GaP and Au/InP samples were annealed in vacuum using a 150°C /min heating rate. The evaporation of volatile components (As and P respectively) were monitored with a mass-spectrometer during the heating cycle. The samples were quenched from different temperatures, characterized by typical points of the evaporation vs temperature curve. In this paper the RBS spectra of the samples heat treated in this way, will be discussed. After the heat treatment significant change in the surface morphology was observed by scanning electron microscopy. Different grains and protrusions appeared which belong to different intermetallic phases formed as a result of the interaction. Using X-ray diffractometric measurements we found Au 2 Ga and s-AuGa phases in the Au/GaAs samples. The same phases were also identified in the Au/GaP system. In the case of Au/InP contacts the phase identification is very difficult. The formation of Au 3 In 2 phaase is indicates by the X-ray spectra of the heat-treated Au/InP samples.