What is Silicon Dioxide?
Silicon Dioxide (SiO2), often referred to as silica, is a chemical compound that is an oxide of silicon. It is naturally found in quartz but is synthetically grown on silicon wafers for use in the semiconductor industry.
Why is it used in Semiconductors?
SiO2 is the backbone of the modern electronics industry due to its incredible properties:
- Electrical Insulation: It has high electrical resistivity, making it an excellent insulator (dielectric) to separate conductive parts of a chip.
- Surface Passivation: Thermal oxide protects the silicon surface from impurities and defects, stabilizing electrical characteristics.
- Masking: It serves as a hard mask during ion implantation or diffusion processes (dopants penetrate silicon but are blocked by SiO2).
- Gate Dielectric: Thin layers of oxide are used as the gate dielectric in MOSFET transistors.
Cross-section of thermal oxide growth on a silicon substrate.