[en] This review discusses experimental techniques used for determining the variety of observables in ion-bombardment induced erosion of solid surfaces. Boundary conditions for performing reproducible and accurate sputtering yield measurements are formulated. To this end, an inventory is made of the observed systematics in several phenomena accompanying sputtering and of the more regular exceptions to the general trends, also, a brief treatment of some theoretical predictions is given, based on the available literature. Following this extensive survey, the merits and limitations of a number of measurement methods, tailored to study one or more different observables, are discussed. Techniques that seem widely applicable or highly promising are emphasized. (author)

No abstract available

[en] Sputtering yields of Zn were determined for bombardment with Ne and Xe ions at normal incidences in the energy range 0.2-20 keV under ultrahigh vacuum conditions. Mass selection was employed and the energy spread was limited to a few electron volts. High fluences of the order of 3 X 10¹⁷ cm^-2 were used to obtain stationary state yields. The yields were determined from accurate weighing of the samples prior to and after the irradiation stage. The measured yields obtained in low current density bombardments are in excellent agreement with predictions from Sigmund's linear cascade theory. There is no evidence of an anomalous, spike-like, cascade behaviour, in sharp contrast to what could be expected on the basis of experimental systematics or theoretical considerations. Yields measured for 20 keV Ne⁺ bombardment of Zn at high flux show a sharp deviation from the Sigmund estimate. Tests have revealed this to be induced by beam heating of the target. The huge yields observed, however, cannot be attributed to a simple evaporation process but must be interpreted as tentative evidence of a so-called thermal spike. (Auth.)

[en] Many groups have investigated the interaction of surfaces with ion beams, with and without simultaneous exposure to a reactive gas, as a model simulation system for plasma etching. On the basis of their experimental evidence current understanding of ion beam assisted etching of semiconductors is reviewed. The discussion is restricted to technologically important ions with atomic number Z or approx. 6 in the energy range 0.25-25 keV. This allows for a meaningful comparison with predictions from linear cascade theory. First, physical sputtering by noble gas ions will be discussed. Next, reactive and molecular ions are treated. It is shown that their sputtering yield behaviour is not dramatically different from that of inert gas ions and that chemical contributions can reasonably be accounted for. Finally, chemical sputtering of materials by simultaneous exposure to ion bombardment and a reactive gas flow is examined. Observed systematics in absolute etch rates and energy distributions of emitted reaction products point to a number of parallel acting mechanisms. Adsorption and subsequent ion beam mixing of the reactive gas into the surface, ion induced desorption, electronic excitation of the target, surface temperature and the chemical activity of the gas can each dominate the detailed etch behaviour. In spite of the fact that the broad trends in chemical sputtering apparently agree with a collision-cascade-like ejection mechanism, this multitude of interactions presently prohibits development of quantitative models. (author)

[en] Recently proposed semiempirical formulae for the sputtering yield near threshold energy are examined. By simple theoretical and experimental arguments it is shown that no reliable threshold energies can be extracted from experimental data on the basis of such expressions, as these formulae cannot be used in the energy range where they discriminate against another. (author)

[en] Elementary processes occurring at solid surfaces immersed in low pressure plasmas are reviewed. In particular mechanisms leading to anisotropic or directional etching are discussed. The crucial role of ion bombardment is emphasized. First a brief summary of the interaction of (excited) neutrals, ions and electrons with targets is given. Next various aspects of sputter-etching with noble gas and reactive ions are surveyed. Finally it will be argued that synergistic effects, invoked by ion bombardment of a surface under simultaneous exposure to a reactive gas flux, are foremost important in explaining anisotropic plasma etching. It is shown that the role of the ions is not merely to stimulate the chemical reaction path but rather that the active gas flow chemically enhances the sputtering. (author)

[en] Some methods and formulae are discussed to estimate g-factors of low-lying states. The shell-model picture is used in the derivation of all expressions. The active (outer) nucleous determine the properties of the nucleus. First, the additivity relation for g-factors of neighbouring nuclei is discussed. Next, the separation of g-factors into an isoscalar and an isovector part is used to study nuclei with atomic mass A<=55. The results of calculations with these relations are compared with experimentally known g-factors and a good agreement is found

[en] The claim that the systematics observed in high-energy ion-beam-mixing experiments applies equally well to broadening observed in low-energy sputter depth profiling studies is addressed. Taking the expression for energetic mixing derived by the Caltech group at face value, it is shown that under fairly general assumptions this can be cast into a more tractable analytical formula. Essentially the final result reads that the broadening at low impact energy E is proportional to E^1/2 cos θ for not too glancing angles of incidence (θ<60deg). The prefactor turns out to be independent of projectile type and only contains thermodynamic quantities determining the efficiency of mixing. Published experimental data support the above-sketched behaviour. Some corroborative data for a deltalike Sb dopant distribution in Si profiled with low energy O₂⁺, Ar⁺ or Xe⁺ primary ions has been obtained. (orig.)

[en] The transient field phenomenon is studied. The dynamical behaviour of this field must be known in order that g-factors can be extracted from the measured precessions. In previous experiments the measured precession angles were found to increase approximately proportionally with velocity for ²⁸Si in Fe. The associated strong field (1000 T) at high velocity have been explained by the capture of polarized electrons from the ferromagnetic host into bound atomic s-shells of the moving nuclear ion. Here precession measurements on ²⁰Ne and ²⁴Mg at various velocities (to v/c approximately 0.06) are described. These measurements, together with data obtained elsewhere, establish the universality of the linear velocity dependence of the field. In addition a marked structure is observed in the atomic number dependence for light ions in iron. It is shown that the field strength can be parametrized empirically if it is assumed that the field is caused predominantly by unpaired polarized electrons in specific s-shells depending on atomic number

[en] Ion-induced secondary electron yields for clean polycrystalline Al, Ti, Ni, Cu, Zn, Mo, Ag, Au and Pb bombarded at normal incidence with 5-20 keV H⁺, H₂⁺, He⁺, Ne⁺, Ar⁺, Kr⁺ or Xe⁺ ions at current densities of about 10 μA/cm² have been measured. Ultra-high vacuum conditions (P < 1 X 10^-7 Pa) and mass-selected particle beams were employed. Target cleaning was achieved by sputtering and monitored by Auger electron spectroscopy. A relatively simple electron yield determination method was used, employing direct current measurement combined with a variable positive target bias voltage. Good overall agreement was found with the scarce experimental data available for the same energy range. A confrontation with predictions of recent sophisticated theoretical work reveals that, even qualitatively, the features of the bombardment energy dependence of the ion-induced secondary electron yields are not well understood. (Auth.)