Technological Methods of Forming Thin Semiconductor Layers. Part 1
Abstract
The review and analysis of the basic technological methods of formation of thin layers of semiconductor materials is presented. The timeframe for the occurrence of thin film technologies and the main centers of their localization are specified. It is shown that nowadays structure, properties and basic methods of obtaining thin films sufficiently well studied for not only simple but also complex, multi-component inorganic semiconductor materials, new areas of application and increase of requirements to the operational characteristics of devices on their basis require improvement of existing technologies and development of new methods for their synthesis, which involves a detailed analysis of the known, and the search for new, progressive methods of preparation. Due to the fact that the main methods for obtaining thin films of inorganic semiconductor materials are vacuum condensation and chemical precipitation, the first part of the review describes the methods of their vacuum application, in particular, thermal spraying in an open vacuum. It is shown that the most common way of obtaining thin films is the thermal spraying under resistive heating of the evaporator with the source material.We analyze the special structural and technological changes and improvement of traditional methods and systems of thermal spraying, which allow to equalize the ratio of the chemical composition of thin films and the source material, improve the stoichiometry of condensates, and ensure their homogeneity.The designs of thermal evaporators with resistive heating of crucibles in an open vacuum with sublimation or evaporation of one and two substances are presented. It is shown how these types of evaporators exclude the transfer of solid particles into evaporating or sublimation into the vapor phase and eliminate direct vapor deposition on the condensation surface, which more or less protects against heterogeneous condensate inclusions.It is shown that the methods analyzed or their modifications are nowadays the necessary means for the creation of thin-film semiconductor structures with predetermined properties, while vacuum deposition, in particular, traditional and modified thermal spraying in a vacuum due to its simplicity(but at the same time its ability to effectively control a large the number of technological factors and create the necessary conditions for the growth of condensates) remains one of the most common ways of obtaining thin films, including inorganic semiconductors.
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