A focused ion beam secondary ion mass spectroscopy system Focused ion beam secondary electron images of polycrystalline aluminum films are valuable in revealing the grain structure of the films with great clarity on a scale of Ͻ50 nm. The contrast mechanism for focused ion beam images in crystalline materials was identified ten years ago as due to crystalline channeling of the ion beam. To our knowledge there has been no report which quantifies this mechanism either with respect to the magnitude of the intensity changes or their angular dependence. The ''critical angles'' of the angular dependence are expected to depend on the source of the secondary electrons, which may be different than the channeled angular dependence of backscattering or sputtering, for example, because of the difference in the distance of approach between the ion and a target atom at which the physical mechanism of interest takes place. The experiment described here quantifies the change in intensity and angular width in the case of channeled 30 keV Ga ions in aluminum thin films. This has been accomplished through a novel combination of focused ion beam images and electron backscatter diffraction measurements. Results of these experiments, and their possible implications for metallurgical imaging, will be discussed.
Electroplated Cu films undergo a remarkable recrystallization at room temperature that has been associated with dislocations and defects arising from the influence of surface-active additives during plating. In the process of plating, the composition of the bath changes as the organic additives are depleted by incorporation into the Cu films or electrolytic decomposition and replenished by fresh additions. Given the sensitivity of the plating process to low concentrations of additives, the properties of the plated Cu might be expected to differ between a freshly prepared bath and an older bath that has processed thousands of wafers and achieved a steady state composition of additives and by-products.In this paper we compare the recrystallization rates of Cu films deposited from two such baths on wafers with damascene trenches of widths from 0.3 to 5 μm. Films deposited from the older bath consistently recrystallize at a faster rate for all trench widths and both barrier materials (Ta, TaN) studied. The concentration of impurities is comparable in the two films. Therefore, the difference in rates is likely due to a difference in defect densities in the film due to different adsorbate/surface interactions during plating. Although the recrystallization rates vary, X-ray diffraction pole figure analysis of films plated from the two baths show no differences in texture. Sidewall growth components are visible in both sets of samples. Data on the influence of the barrier material and trench width on recrystallization rates are also presented.
The dopant-defect interaction in silicon-on-insulator (SOI) material is studied for Si film thicknesses ranging from 60 to 274 nm, with regards to (1) boron pileup and (2) defect-induced boron clustering. Results are obtained on boron-implanted samples and on molecular beam epitaxy-grown deposited-boron samples. The experimental results verify simulations predicting (a) boron pileup at both upper and lower interfaces of the Si film, and (b) no reduction of the boron clustering in SOI compared with bulk silicon.
Articles you may be interested inBrightness measurements of a gallium liquid metal ion source Gallium liquid metal ion source (abstract) Rev. Sci. Instrum. 65, 1355 (1994; Droplet emission from a gallium liquid metal ion source as observed with an ion streak camera A study of time and angle correlations in the ion emission from gallium liquid metal ion sources J. Vac. Sci. Technol. B 6, 482 (1988); 10.1116/1.584046 Measurement of the energy distribution of a gallium liquid metal ion sourceGallium ion clusters Ga n l with n ranging up to 30 have been measured from liquid gallium ion sources using a time-of-flight spectrometric technique. The observations were made as a function of total ion emission current, angle of emission, and temperature of the liquid metal. Under all conditions Ga t is the overwhelmingly dominant species emitted. The cluster data reveal several remarkable features. First, emission of clusters tends to be very low below 2 itA emission cun-ent, to rise steeply with current to 10 or 20 f-lA and decrease for higher current. Second, within the range examined, clusters with n = 8 and 15 have particularly low abundances. Third, the energy distributions of the resolvable clusters are bimodal with characteristic peaks at approximately 30 and 120 eV below the source potential. Fourth, the angular distributions of the clusters are more nearly axial than that of the primary species. The temperature of the liquid metal has no noticeable effect on cluster emission over the range examined. A possible model for cluster formation will be discussed.
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