Silicon Oxynitride – Si2N2O

Silicon oxynitride is a film coating that is a compound of silicon, oxygen and nitrogen. This film is deposited on wafers via PECVD, and undergoes a very similar process to silicon nitride, with nitrous oxide gas (N2O) introduced to hydrides of nitrogen and silicon (NH3 & SiH4) inside a furnace. Using a nitrous oxide precursor leads to fewer hydrogen impurities and improves stability while giving the wafer great crack resistance.

This film has very similar properties to silicon nitride, so they are often used together to planarize multilevel interconnects because they have similar properties, but different etch rates.


SVM PECVD Silicon Oxynitride Specifications:

Thickness:  100Å – 2μm
Refractive index: 1.5 – 1.9
Film stress: 250MPa
Wafer diameter: 50mm300mm


Silicon Oxynitride Deposition Process:

Plasma enhanced chemical vapor deposition (PECVD) is the most common way to deposit silicon oxynitride on wafers. The precursor contains both oxide and nitride, which have different film properties, allowing the film composition to change continuously. The result is a single side film with flexible properties. The ability to change the film properties by influencing the deposition environment is ultimately what allows the film to work well with other coatings like silicon nitride.


Si2N2O coatings suppress boron penetration, improve device reliability, and improve hot carrier resistance in wafers. Hot carrier resistance prevents high kinetic energy electrons from fracturing the crystal lattice or displacing and leaving a hole where the electron was. This makes these films great as an alternative for gate dielectrics when lower temperatures are required. These properties mean silicon oxynitride works great as a final passivation layer, intermetal level dielectric and liner for trench isolation. In other applications it also works as an oxide diffusion barrier for more complex film coatings.

Although silicon oxynitride has a higher dielectric constant than silicon dioxide, it has very similar properties. In temperature restricted specifications, this film works well as a replacement for silicon dioxide.

Silicon Valley Microelectronics has a wide selection of Si2N2O coatings on a variety of wafer diameters, CONTACT SVM today for more information or to request a quote.