Tadahiko Saito

Ionic conductivity of tantalum oxide by rf sputtering

Abstract Tantalum oxide thin films were prepared by rf sputtering. The dependence of deposition conditions (i.e. sputtering power, total sputtering pressure, and oxygen partial pressure) on ionic resistivities for tantalum oxide films were evaluated. The proton conductivities varied from 3.3 × 10 −6 S/cm to −10 S/cm. The activation energy for ion motion varied from 0.25 to 0.4 eV; increasing exponentially with the optical absorption coefficient of the films. Variation in the ionic conductivities could be attributed to changes in the carrier concentrations and mobilities; although, a quantitative assessment was not made.

Properties of tantalum oxide thin film for solid electrolyte

Abstract Tantalum oxide thin films were prepared by RF ion-plating and RF sputtering. Protonic conductivities of the films varied from 10 −5 to 10 −10 S/cm with the condition of deposition. The high ionic conductive film has low packing density and shows strong O-H absorption. It was concluded that the adsorbed water gives much influence to the protonic conduction.

Development of optical coatings for 157-nm lithography. II. Reflectance, absorption, and scatter measurement

The total loss that can be suffered by an antireflection (AR) coating consists of reflectance loss, absorption loss, and scatter loss. To separate these losses we developed a calorimetric absorption measurement apparatus and an ellipsoidal Coblentz hemisphere based scatterometer for 157-nm optics. Reflectance, absorption, and scatter of AR coatings were measured with these apparatuses. The AR coating samples were supplied by Japanese vendors. Each AR coating as supplied was coated with the vendors coating design by that vendors coating process. Our measurement apparatuses, methods, and results for these AR coatings are presented here.

Development of low-loss optical coatings for 157-nm lithography

In the F2 laser lithography, it is essential to reduce the loss of the optical coatings deposited on calcium fluoride lenses. In order to make low loss optical coatings, we have developed measurement apparatus, evaluated the coatings with various analyses, and found a correlation with the optical constants. In this paper we describe the optical loss measurement apparatus and the evaluation results analyzed for either single layer coatings or multi-layer anti-reflection coatings.

Measurement of total integrated scatter of optical coatings for 157-nm lithography

A new Coblentz type scatterometer is developed for evaluation of 157-nm optical coatings. The Coblentz hemisphere has ellipsoidal design for higher sensitivity and stability. The scatterometer works under nitrogen atmosphere keeping away from the organic contamination. Some kind of antireflective coatings are obtained from several Japanese suppliers and evaluated by the scatterometer. Results of the scatter measurement are almost equal except one sample that includes Na3AlF6 layer as low refractive index material. Its extremely high scatter loss could be ascribed degradation by reaction to the water in the air.