Why is silicon dioxide used between layers in an integrated circuit?

In an integrated circuit, silicon dioxide (SiO₂) is used between layers primarily because it serves as a high-quality insulator.

Its role is critical to the functionality of silicon-based devices for the following reasons:

• Electrical Isolation: As an insulator, silicon dioxide prevents unwanted electrical contact between conductive layers or components, ensuring that current flows only through intended pathways.
• Ease of Integration: One of the primary reasons silicon supplanted other materials like germanium in device fabrication is that silicon dioxide is exceptionally easy to incorporate into the manufacturing process as part of a silicon-based device.1

By providing a stable, reliable insulating barrier, silicon dioxide allows for the complex, multi-layered architecture required in modern integrated circuits.1