Analysis of thickness unevenness of the epitaxial silicon layer during deposition from sublimation sources in a vacuum

Background. Si layers, grown by sublimation molecular-beam epitaxy (MBE), are uniform in thickness on a small area (1-4 cm$^2$). Therefore, for further development and industrial use of this method it is necessary to realize epitaxial growth on substrates of sufficiently large area. The aim of this work is to identify conditions of deposition of silicon layers with uniform thickness distribution over the area of a substrate with a diameter of 100-200 mm from sublimation sources. Materials and methods. In order to increase thickness uniformity of epitaxial Si layers, deposited in the process of sublimation MBE, the possibility of using several identical source Si was observed. A sublimation Si source is a rectangular bar with cross-section of 4x4 mm and the length of 120 mm, heated to the working temperature. The proposed model for calculation of thickness distribution of the epitaxial Si layer is based on the fact that the linear density of distribution of Si particles at the surface of a substrate has a form close to the normal distribution law. Results. The authors obtained the experimental and calculated profiles of thickness distribution of epitaxial silicon layers along with the substrate diameter. The calculation results agree well with the experiment. The possibility of obtaining uniform layers of silicon while using three sources of sublimation is showed. Conclusions. In order to obtain the desired degree of uniformity of the epitaxial layer, it is necessary to use several sources of sublimation. For the case of three sublimation sources the authors identified geometric and structural parameters of the mutual arrangement of a substrate and the sublimation sources in a vacuum chamber.