Formation of SiO2 Dendritic Structures During Annealing of Silicon on Insulator Wafers

Silicon-based sensors and actuators are the most prominent applications of silicon-on-insulator (SOI) microelectronic devices. The main reason for defects of these products is the low mechanical properties of the plates, due to their surface defects. To find out the causes of defects, studies are carried out by methods of measuring electron work function, scanning electron microscopy, atomic force, and secondary ion microscopy. It shows that in the case of defective SOI samples (doped by boron) on the silicon surface, there are silica fiber structures formed in zones having copper impurities. It is suggested that the fibrous SiO2 structure appeares as a result of the catalytic copper action on the process of silicon oxidation, causing the formation of polymeric fibers, at the end of which there are "caps" of copper. Presence of silica fibrous structure on the surface causes abnormally low electron work function values (<4.0 eV). Study of the heat treatment effect (room temperature divided by 900 degrees C) of silicon wafers doped with boron and antimony impurities on the surface morphology made it possible to identify the changes that occur, to determine the roughness and the size of surface micro-roughness, and to optimize the technological routes for MEMS manufacturing.