Anodization behavior of Al/Mo/Al multilayer films is studied by the method of depth profiling with Auger electron spectroscopy. The leaving out of the molybdenum layer by the drastic transport is observed. The results are discussed on the basis of the mobility of molybdenum cations.

Stoichiometries at interface layers of Ta-Al-N anodized films have been investigated. It is shown that the chemical states of interfaces are consisting of stoichiometric Ta2O5, Al2O3 and metals. Off stoichiometries at interfaces are discussed with respect to dissipation factors.

We have studied the oxidation state of Al/Hf and Ta/Hf bi-layered films by AES/XPS analysis. The anion transport process through the upper oxidized layer which is oxygen supply medium for Hf oxidation is examined. It is found that the oxidation reaction of Hf occurring with sufficient anion transport through the upper oxidized layer corresponds to the excellent properties as capacitors.

Formation process of the anodic oxide film of hafnium for use as a thin-film capacitor has been examined by the current-voltage characteristics of the anodization and the in-depth analysis of formed oxide using Auger electron spectroscopy. It is found that the oxide growth obeys three different rate laws such as the linear rate law at first and next the parabolic rate law during the constant current anodization, and then the reciprocal logarithmic rate law during the constant voltage anodization following after the constant current process. From the Auger electron spectroscopy analysis, it is found that the shape of the compositional depth profile of the grown oxide film varies associating with the rate law of oxidation obeyed. The variation of depth profile correlating with the rate law is discussed with respect to each elementary process such as the transport and/or the reaction of chemical species interpreted from the over-all behavior of anodization process. It is revealed that the stoichiometric film having an interface with sharp transition, which is favorable for obtaining excellent electrical properties of the capacitor, can be obtained under the condition that the phase-boundary reaction is the rate-determining step of the anodization. The constant voltage anodization process also satisfies such circumstances and therefore can be the favorable method for preparing highquality thin-film capacitors.

We have successfully prepared low anodization voltage high-quality capacitors using anodized hafnium films with the anodization voltage of 40 V under the preferable conditions of anodization and heat-treatment.