Dependence Of Depth Resolution Research Articles

Dependence of depth resolution on primary energy of low‐energy Ar+ Ions (100–1000 eV) in AES sputter depth profiling of GaAs/AlAs superlattice

AbstractThe dependence of the depth resolution on the primary energy of low‐energy Ar+ ions in Auger electron spectroscopy (AES) sputter depth profiling of an ISO reference material GaAs/AlAs superlattice was investigated for the ion incidence angle of 50° from the sample surface normal. The depth resolution was found to improve as the square root of the primary energy of the ions as the primary energy decreased from 1000 to 200 eV. In contrast, a deterioration of the depth resolution was observed at 100 eV, which was induced by the difference in the etching rates between GaAs and AlAs and preferential sputtering. Further investigation of AES sputter depth profiling under irradiation of 100‐eV Ar+ ions at the incident angle of 70° revealed that the difference in the etching rate and preferential sputtering could be suppressed by changing the incident angle from 50° to 70° , leading to a depth resolution of ∼1.3 nm with 100 eV. The present results confirmed that glancing incidence is effective in achieving higher depth resolution from the point of view of the reduction of not only atomic mixing but also the difference in the etching rates and preferential sputtering. Careful attention is required for optimizing conditions of low‐energy ion irradiation in sputter depth profiling using the GaAs/AlAs reference material. Copyright © 2006 John Wiley & Sons, Ltd.

Influence of crystalline structure and amorphous materials in the depth resolution of sputter etching

AbstractThe dependence of depth resolution Δz/z on the sputtering angle θ is investigated for three sputter‐deposited films: Cr (bee), SiNx (amorphous) and FeCoTb (amorphous). The depth resolution for the Cr system exhibits two maxima at θ = 35° and 45°. These are characteristic for bee textured material but different from fee textured material. The amorphous films show a very weak dependence, if any, owing to the absence of crystallites and crystalline texture. These results are in accordance with channeling theory.

Optimization of rotational Auger depth profiling

AbstractThe dependence of depth resolution on the rate of sample rotation in rotational Auger depth profiling was systematically investigated for Cu/Fe multilayer films, using 1–3 keV Ar+ and Xe+ ions as projectiles. Except for Xe+ ion bombardment at 1 keV, the depth resolution was invariably improved by increasing the rate of rotation up to a critical value. The resolution improvement was more pronounced for Ar+ sputtering, but at and above the critical rate the resolution was nearly constant, independent of the sputtering conditions. The critical rotation rate depended on ion species and energy, decreasing with lowering ion energy and increasing ion mass. For 1 keV Xe+ the depth resolution obtained without rotation was comparable to that obtained with sample rotation, indicating that sample rotation was not the sole means to attain high depth resolution. As confirmed by scanning electron microscopy, highly resolved depth profiles for rotated samples were due mainly to reduced surface roughening. Evidence is also presented that at the critical rate of rotation the depth resolution was limited by the intrinsic interface roughness.

Depth resolution in Auger depth profile analysis of aluminum metallization in microelectronics: The effect of crystalline texture

Due to the wide application as metallic interconnect material, aluminum alloys are important for integrated circuit technology. Analysis of aluminum thin films by Auger depth profiling, however, is impeded by severe roughening of the aluminum surface during the ion bombardment. It is shown that this is caused by the effect of ion channeling on the sputtering yield, resulting in an orientation-dependent sputter rate of the individual crystallites. Because of the strong crystalline texture of aluminium films, roughening is enhanced if the ion incidence coincides with the preferred orientations of the channeling axes. The dependence of depth resolution on ion impact angle, ion species and ion energy can be explained qualitatively by Onderdelinden's theory of single-crystalline sputtering.

AES depth profiling of TaSi multilayers: dependence of depth resolution on Ar + ion energy and incidence angle : S Hofmann, Max-Planck-Institut für Metallforschung, Institut für Werkstoffwissenschaft, Seestr 92, 7000 Stuttgart 1, FRG and W Hösler and R von Criegern, Siemens AG, ZFE F1 FKE 4, Otto-Hahn-Ring 6, D-8000 München, FRG

AES depth profiling of TaSi multilayers: dependence of depth resolution on Ar + ion energy and incidence angle : S Hofmann, Max-Planck-Institut für Metallforschung, Institut für Werkstoffwissenschaft, Seestr 92, 7000 Stuttgart 1, FRG and W Hösler and R von Criegern, Siemens AG, ZFE F1 FKE 4, Otto-Hahn-Ring 6, D-8000 München, FRG

Sputter‐depth profiling in AES: Dependence of depth resolution on electron and ion beam geometry

AbstractThe precise geometrical relationship between the ion and electron beams and the sample affects the depth resolution of sputter‐depth profiles in AES. A theory is presented which predicts this instrumental depth resolution by considering the shape of the ion‐eroded crater and the corresponding orientation of the electron beam. The variation in depth resolution is analysed for a range of conditions including (a) varying ion and electron beam diameter (b) the angular orientation of the electron and ion beam and (c) the effect of misalignment of the two beams.

Depth resolution in sputter profiling

The dependence of depth resolution on sputter depth due to various parameters is theoretically estimated. Comparison with experimental work of different authors shows the validity of the proposed model.