Tatsuhiko Adachi

Electrical Properties of Metal-Oxide-Containing SiO2 Films Formed by Organosiloxane Sol–Gel Precursor

High-quality SiO2 film formation is important for many applications, such as large-scale integration (LSI) circuit and micro-electro-mechanical system (MEMS) industries. We evaluated the structural and electrical insulation properties of SiO2 films using an organosiloxane-based silica sol–gel precursor derived from a mixture of tetraethoxysilane (TEOS) and methyltrimethoxysilane (MTMS) by changing the molar ratio of TEOS/MTMS. This sol–gel precursor was converted not only to a low-dielectric-constant film with a relative dielectric constant of 2.8 but also to a dense SiO2 film by optimizing baking conditions. The dense SiO2 film from this sol–gel precursor has excellent dielectric characteristics of low leakage current density and high breakdown voltage, whose values are comparable to those of thermal oxide SiO2 films. Furthermore, the breakdown field intensity of these films was improved by adding a small amount of metal oxides, such as TiO2, HfO2, and ZrO2. A maximum breakdown field intensity of 15 MV/cm can be achieved in the case of 10% TiO2 addition.