Hillocks, surface protrusions from thin metal films, have been observed in Al, Al/Cu, Pb, and other materials. Platinum films are widely used as substrates for the deposition of ferroelectric thin films because of their superior oxidation resistance. However, hillock formation in platinum films has not been reported in the literature. In this work, we report the appearance of hillocks in platinum in Pt/Ti bilayers on oxidized silicon wafers. Platinum films 250 to 300 nra were deposited by ion beam sputter deposition at 25°C and 300°C onto a 70 nm Ti film on oxidized Si wafers. The wafers were then heated in flowing argon to 600°C, held 1 hr at 600°C, and cooled to room temperature while the wafer curvature (and hence the film stress) was measured with a laser beam deflection technique. At 600°C, compressive stresses of 0.1 to 0.4 GPa, due to thermal expansion mismatch, developed in the metal films. The platinum surface, initially flat, showed strong hillocking after the anneal. Cross-sectional TEM revealed that severe Ti/Pt interdiffusion occurred, in one case leading to a Ti layer on the top surface.

Effect of secondary electron emission on sheath potential in an electron cyclotron resonance plasma Lowtemperature in situ cleaning of silicon (100) surface by electron cyclotron resonance hydrogen plasma J. Vac. Sci. Technol. B 13, 908 (1995); 10.1116/1.588204Silicon surface electrical properties after lowtemperature in situ cleaning using an electron cyclotron resonance plasmaIn situ electron cyclotron resonance plasma surface cleaning of silicon

The evolution of strain in the Pd–Si system during the growth of Pd2Si thin films on Si (100) substrate has been followed in situ using a double optical beam technique. As was observed for the Pt–Si system, the reaction to form Pd2Si yields a compressive intrinsic surface film stress as well as for the silicon-rich silicides as proposed by Angilello et al. [Thin Film Interfaces and Interactions, edited by J. Baglin and J. Poate (The Electrochemical Society, Pennington, NJ, 1980)]. A transmission electron microscopy analysis has revealed grain growth during the formation of Pd2Si which cannot account for the compressive film stresses. The formation of silicide at the interfaces rather than the overall change in volume agrees with the sign of the stresses formed.

An argon electron cyclotron resonance plasma has been applied to the SiO2/Si system, in order to investigate the SiO2 film etching reaction and the Si surface damage using in situ spectroscopic ellipsometry (SE) and single wavelength ellipsometry. Ex situ atomic force microscopy was used to characterize the surface morphology and compare with SE results. Experiments included a range of ion dose rates from 3×1015–2×1016 ions/cm2 s, at substrate temperatures of floating temperature (<100 °C) and 700 °C, and doses from 1016–1019 ions/cm2 at low ion energies from 0 to 100 V dc bias. Etch rates of about 20 nm/min for SiO2 have been achieved at −50 V bias. At floating temperature a critical minimum ion energy for removal of the oxide is about −25 V bias, and the damage includes a roughness layer and an interface amorphous layer which increased with ion energy. At 700 °C no amorphous layer was observed and the Si roughness layer varied with the ion dose from 0.4 to 30 nm for 1017 and 1019 ions/cm2, respectively after SiO2 removal. The determination of the optimum cleaning end point was achieved using real time ellipsometry.

The process of atomic transport in the silicide during oxidation of silicide layers formed on Si substrates has been analyzed by means of implanted inert markers. The results confirm that CrSi2 oxidizes via the diffusion of Cr atoms towards the Si substrate, and reveal that the same type of transport occurs in VSi2, which is in opposition to the growth of these disilicides that proceeds via Si motion. Moreover during the oxidation of both VSi2 and CrSi2, the diffusing metal atoms are accompanied by a large proportion of the Si atoms from the silicide which also diffuse towards the substrate. Thus, the experimental evidence now available reveals that all the silicon-rich silicides, in increasing atomic numbers from TiSi2 to NiSi2, oxidize with the formation of metal-free SiO2 in a process that involves the diffusion of both metal and Si regardless of the predominant moving species during silicide formation. In CrSi2, VSi2, as well as TiSi2, with similar structures, examination of the structure shows that diffusion should occur via a vacancy mechanism. The thermodynamic conditions that prevail during oxidation lead indifferently to metal diffusion in one direction or Si diffusion in the other. Any selection between one mechanism or the other has to be dictated by kinetic conditions relating to the relative mobilities of the two atomic species. What is known about this is discussed in detail. Finally it is proposed that the observed dual, parallel diffusion of metal and Si, results from the very nature of the oxidation process which modifies the chemical potential of the atoms at the surface being oxidized. Thus is created a force that drives some of the atoms away from the surface, into the inside of the samples. The best known example of this behavior is the often observed ‘‘injection’’ of interstitials during Si oxidation, but a similar process is at work in silicide oxidation, with somewhat similar results. Volume effects, thought to play an important role in solid state chemical reactions, are remarkably well illustrated by the oxidation of silicides.