Technological Methods of Forming Thin Semiconductor Layers Part 3. Сathode Sputtering
Abstract
The peculiarities and the basic technological ways of forming thin layers of semiconductor materials in vacuum by the method of thermal sputtering in quasi-closed volume are analyzed. The disadvantages of thermal deposition of thin films in open vacuum for multicomponent semiconductor compounds are indicated. We present designs of special collapsible evaporation chambers for quasi-closed volume thermal vacuum deposition, which contain the source material and the substrate in quasi-insulated conditions, and allow to create and control the necessary temperature ratios between the evaporator, substrate, walls and other structural elements. It is shown that the spatial distribution of temperature in the mentioned above chambers provides the evaporation (sublimation) of the starting material, the reflection of vapors from the heated walls, the intense exchange interaction between the gas phase and the condensation surfaces, which contributes to the diffusion mechanism of the transfer of matter and thermodynamically balanced process of film growth. It is shown that for all modifications the conditions of isolation of the localized volume and equilibrium of the condensation process are fulfilled to a greater or lesser extent by creating the required temperature gradient. However, it is problematic to use such designs for mass production because of their complexity and technological features. That is why, the method of thermal deposition of thin films in a quasi-closed volume is most often used in the manufacture of epitaxial single crystalline layers for research and experimental development, and for industrial production it is very effective to develop methods for obtaining thin films that combine on the one side universality of open vacuum, and on the other allow to approximate the processes of evaporation (sublimation) – condensation to thermodynamic equilibrium, for example, different variants of “hot walls”. It is stated that the analyzed methods or their modifications are today a necessary means of creating thin-film semiconductor structures with predetermined properties. It is stated that the analyzed methods or their modifications are today a necessary means of creating thin-film semiconductor structures with predetermined properties.
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