Titanium Silicide Formation in Presence of Oxygen

C Nobili,G De Santi,G Ottaviani,F Nava,M Costato,G Queirolo

doi:10.1155/1992/94394

C Nobili, G De Santi + Show 4 more

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https://doi.org/10.1155/1992/94394

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Abstract

In-situ resistivity vs. temperature, Rutherford backscattering spectrometry, Auger electron spectroscopy and X-ray diffraction measurements have been performed in order to study the effects arising from the presence of oxygen in the annealing ambient on the integrity of amorphous films of TiSix, with x ranging from 1.45 to 2.1. Crystalisation occurs around 400 C. The presence of oxygen produces the formation of silicon and titanium oxide around 500 C. Critical analysis of the experimental results have indicated that metal oxidation is inhibited when an excess of silicon is present, which suggests the use of a sputtered Si coating cap as a medium capable of effectively decoupling the silicide film from oxygen. This avoids unwanted Ti oxidation even in heavily oxygen contaminated ambients up to the highest temperatures used for the formation of low resistivity titanium disilicide.

Highlights

Among the refractory metal/silicon compounds, titanium-disilicide is the material with the lowest electrical resistivity at room temperature1,:
We have seen that the amorphous films of titanium-silicon alloys as deposited exhibit a high electrical resistivity, and that suitable heat treatments are necessary to FIGURE 10b X-ray diffraction (XRD) spectra taken in a Ti-rich sample as deposited, after heating in purified atmosphere up to 420 C and up to 800 C
According to XRD analysis, it corresponds to the transformation from the amorphous to crystalline bc C49 TiSi2 phase

Summary

Introduction

Among the refractory metal/silicon compounds, titanium-disilicide is the material with the lowest electrical resistivity at room temperature1,:. As a consequence it is preferred when interconnections in silicon integrated electronic devices are required. The transformation kinetics of the silicon-titanium compounds are expected to be influenced by the presence of impurities, such as oxygen, carbon and nitrogen. These impurities can be (i) incorporated in the metal film during deposition, (ii) incorporated in the polysilicon film used as a substrate in the polycide gate structure, or (iii) located at the metal/silicon interface

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