Investigation of the Initial Silicon-on-Sapphire Layer Formed by CVD Techniques

The complexity of optimizing the technology of heteroepitaxy is an important limiting factor of the application of silicon-on-sapphire (SOS) structures. In order to eliminate this technological barrier, we study the gas-phase formation of the initial silicon layer on the R-plane of sapphire. The parameters of the deposited layers are analyzed using industrial quality-control methods and X-ray diffraction, SEM, and Raman-spectroscopy. The resistivity-distribution profiles are obtained by the spreading-resistance (SRP) method. It is shown that the initial stage of growth at a temperature of 910–930°C leads to a decrease in the autodoping of the silicon layer with aluminum from the substrate. Heat treatment of the initial layer formed at a temperature of 945–965°C makes it possible to obtain a high structural quality of SOS structures in a wide range of deposition temperatures (960–1005°C) of the main layer layer. Comparison of the SOS structures obtained with optimal parameters of the developed mode and by means of the conventional process shows a decrease in the full width at half-maximum of the rocking curve to ~0.24°, a decrease in mechanical compressive stresses to 0.8–1.96 GPa, and homogeneity of the resistivity profile to a depth of 180–350 nm. Application of the developed technological modes can significantly improve the homogeneity of the control parameters of the SOS in a single process, which improves the performance of the manufacturing process.