Carrier lifetime and xray imaging correlations of an oxideinduced stacking fault ring and its gettering behavior in Czochralski siliconEffect of a vacuum ion gauge on the contamination of a hydrogenpassivated silicon surface

In relation to intrinsic gettering, the dependence of denuded zone width and thermally induced microdefect density on thermal conditions are investigated in a three-step annealing procedure consisting of high temperature annealing, low temperature, and dry O2 oxidation at 1000 °C. Additionally, depth profiles of interstitial oxygen concentrations are studied using thermal conversion. The obtained results show that at least an initial interstitial oxygen concentration above 8×1017 cm−3 is required to achieve efficient intrinsic gettering. The depth profile obtained after the third annealing is not the simple out-diffusion profile approximated by an error function, but one with a peak in the denuded zone. The dependence of depth profiles on a third annealing condition indicates that the formation of the peak in the depth profile can be ascribed to a reduction of interstitial oxygen resulting from precipitation in the bulk region. In order to explain the obtained profiles, we propose a simple diffusion model which takes into consideration the oxygen precipitation in the bulk region. By comparing the calculated profiles with the experimental ones, it is proved that this model can be used to estimate depth profiles under various annealing conditions.

The three-dimensional stress distributions in a substrate due to a rectangular film deposited on the substrate are calculated by linear elastic theory on the assumption of a concentrated force at the film edge. Furthermore, on the basis of the results, resolved shear stress distributions in a (001) silicon crystal substrate are calculated to evaluate the character of the dislocations generated at the film edge. These calculated results are compared to experimental ones obtained in a sample of a (001) silicon substrate with a 3×3-mm-square pattern of Si3N4 film. The results show that the glide planes and Burgers vectors of the dislocations generated at the film edge can be determined by a simple rule.

We have investigated the intrinsic gettering (IG) of Cu in silicon wafers. Oxygen precipitates for IG were formed in wafers subjected to two-step annealing consisting of thermal treatment for 16 h at 800°C, then for 0-16 h at 1000°C. Cu was deposited on the back surface by dipping the wafers into a contaminant solution, and introduced into the wafer bulk from the back surface by heating for 5 min at 1000°C. The surface concentration of Cu was measured by total-reflection X-ray fluorescence. We found that the gettering efficiency, which was determined from the difference between the surface concentration on reference wafers and the corresponding concentration on the IG-treated wafers, depends on the Cu contamination concentration. Moreover, we used a simulation based on the Fokker-Planck equation to analyze the data with regard to the dependence of gettering efficiency on oxygen precipitate density. As a result, we have shown that the total number of oxygen precipitates, rather than their size determines the gettering efficiency. These experimental and calculated results can provide useful information for achieving effective IG of Cu. © 2002 The Electrochemical Society. All rights reserved.

The density of dislocations generated at Si3N4 film edges on silicon substrate by selective oxidation is measured and the relation between the selective oxidation conditions and dislocation generation at the film edges is investigated. Dislocations are observed using Secco etching. The results show that the density of dislocations does not continuously increase with oxidation temperature, but decreases markedly at temperatures above 1000°C. A further experiment with recessed oxide structure reveals that the generation of dislocations depends strongly on the cross‐sectional structure of the sample These results are interpreted in terms of viscous flow of SiO2 film. Another experiment suggests that high pressure oxidation is not effective for suppressing dislocation generation, although it is useful for reducing oxidation time. Finally, collector‐emitter shorts of transistors in bipolar integrated circuits are examined quantitatively using a simple statistical method in relation to the dislocations generated at Si3N4 film edges.