Reactive sputtering techniques have been widely used to fabricate compound thin films. Transition of the target between metallic mode and compound mode is a characteristic feature of reactive sputtering, and needs to be carefully controlled. In this paper, the critical condition for the target mode transition in the Al-O₂ system was studied. First, the conditions for the transition were investigated by varying the amount of sputtered Al atoms and O₂ gas introduced. The ratio of the number of sputtered Al atoms to the number of O atoms introduced was found to be one of the key parameters for the target mode change. Next, the time-dependent variation of the target mode was investigated. The transition time from metallic mode to oxide mode was found to depend on the amount of Al atoms deposited on the chamber wall during pre-sputtering. These results indicate the important role of the chamber wall, which getters reactive gas molecules.

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  In reactive sputtering of titanium target in the oxide mode, oxygen atoms are selectively sputtered from the target surface, which leads to a significant reduction of deposition rate of TiO₂ films. Utilizing this phenomenon, we developed a sputtering type oxygen radical source. Combining this oxygen radical source with a titanium sputtering source which is operated in metal mode, we showed that a high rate deposition of TiO₂ films above 40 nm/min was achieved. In addition, it was confirmed that the crystal structure of the film (anatase and/or rutile) was easily controlled by the control of the amount of oxygen radicals and titanium atoms incident on the substrate surface. Low temperature deposition of crystallized TiO₂ films was also attempted by using this sputter-deposition method. As a result, it was found that deposition of a well crystallized TiO₂ films on unheated substrate could be realized by using crystallized TiO₂ seed layer and a proper ion bombardment.

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  The incorporation of oxygen impurities under ambient environment conditions during reactive sputter deposition of titanium nitride (TiN) films has been studied. TiN films, prepared by DC sputtering of a Ti metal target in 100% N₂ at 1 Pa in an ultra-high vacuum (UHV) sputtering apparatus, were essentially free from oxygen. When oxygen was intentionally introduced into the vacuum chamber, an impurity level of a few atomic percent was obtained at a partial pressure of 3×10⁻⁴ Pa, but the percentage increased rapidly to 10-20 at.% when the partial pressure was 1×10⁻³ Pa or above. It is shown that the increase in the oxygen incorporation is not well explained by the oxygen impingement rate calculated from the partial pressure. We demonstrate that the impurity concentration is related to the ratio of the number of oxygen atoms introduced into the chamber to the number of Ti atoms sputtered from the target. This suggests that oxygen gettering by Ti atoms deposited on the chamber wall significantly reduces the oxygen pressure during deposition and that oxygen incorporation in the film is governed primarily by the total amount of sputtered metal.

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  Electron Stimulated Desorption (ESD) is one of surface analysis techniques using an excitation of adsorbed atoms by electrons. Using a scanning electron beam it is possible to map a two dimensional ESD distribution of adsorbed hydrogen. We detected striped pattern of hydrogen desorption from the stainless steel surface flattened by the processing with the lathe. The hydrogen gas was supplied to backside of the sample membrane, penetrates the sample inside, and arrives at the surface. The ESD pattern of hydrogen reflects density of the dislocation in martensite that occurred by lathe processing on the austenite steel surface.

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  Density functional theory-based investigation is performed to give generalization to changes in the electronic structures of alkali metal—metal surface systems in relation with the work function. The analysis of the density of states (DOS) profiles revealed that the position of the state corresponding to the interaction of adsorbed alkali metals on W(110) can provide insight to the variation of work function of the system. At low coverage, the state resides in the unoccupied region of the DOS profile. Depolarization happens at high coverage when the state shifts to the occupied region. This characteristic is exhibited by the different alkali metals considered in this work: Li, Na, K, Rb, and Cs; providing generalization to the work function variation in relation to their electronic structures.

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