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Dry etch behavior of Fe in inductively coupled chlorine-based plasma at elevated temperatures has been investigated. Etch rates up to 300 nm/min at 190 °C were achieved, with good selectivity towards SiO2 and Al2O3 masks. Etching did not take place in pure Cl2 plasma or Ar/Cl2 plasma, but required the addition of a few percent BCl3 or SiCl4. The process was found to be a combination of spontaneous and ion enhanced chemical etching. Simultaneous exposure to ultraviolet light from an external source did not enhance the etch rate, but did shorten the inhibition time of the etching.

Dry etch behavior of CoNbZr in an inductively coupled plasma of Cl2/BCl3 at elevated temperatures has been studied. Etch behavior of the alloy is ion induced with a strong chemical enhancement. The etch rate shows nonstoichiometric behavior when compared with the constituting elements. The increase by about 35% is attributed to interactive effects. A further enhancement up to about 40% is obtained under simultaneous exposure of deep ultraviolet irradiation. A fast anisotropic dry patterning process for CoNbZr has been developed, with etch rates up to 300 nm/min at 220 °C.

Summary The soils which occur along the southern shore of the Caspian Sea, in the Mazanderan Province, which is one of the main rice-producing regions in Iran, are formed mainly from young alluvial deposits in which pedo-climate is considered to be the major soil-forming factor. According to differences in pedo-climate, the soils have been differentiated into soil associations which are related to the topographical situation in which they occur, namely the several landscapes characteristic of the morphology of a we11-developed riverine plain. The occurrence of salty soils can be explained by the influence of the Caspian in the past, and their reclamation, although theoretically possible by drainage improvement, the application of soil amendments, and adequate leaching, has been found to be very difficult in practice. Soil analyses have shown interrelationships between natural vegetation or crop yield and salty conditions. The soils have been further classified according to their suitability for paddy-rice cultivation, particularly with regard to the economy of irrigation water. As none of the irrigability classifications yet devised appears to be suitable for the purpose of classifying rice soils, a special system has been developed to meet the circumstances prevailing in Mazanderan.