Silicon dioxide is the most commonly used insulator material in IC technology and in the other fields of silicon device fabrication technology. This chapter explains the various aspects of the growth and deposition of silicon dioxides. It also shows with example the utilization of different kinds of silicon dioxides for various purposes in the fabrication of MEMS devices. It also gives some idea on the common oxidation processes found in MEMS manufacturing. Growth methods of silicon dioxide include thermal oxidation. When a silicon wafer experiences an oxidizing ambient at the elevated temperatures the silicon dioxide is chemically grown on the surface. If the oxidizing ambient is steam, the process is known as wet oxidation and if pure oxygen gas is employed, the process is called dry oxidation. This chapter explains the dopant effects, chlorine effects, pressure effects, stress effects, and multidimensional effects in oxidation processes. Oxidation-induced defects of silicon are also described. Structure and properties of Silicon Dioxides are explained in detail. The thermally grown silicon dioxide on silicon is amorphous. The noncrystalline phase likes to develop towards the thermodynamic equilibrium structure by the process is known as the devitrification is explained. This chapter touches on the topics of oxide processing, cleaning and etching. The intention of the cleaning is to remove particles and photoresistant residues, metallic impurities, and organic contamination. Etching is a method for the material removal in many industrial processes.