Silicon Oxynitride (SiNxOy) LPCVD

Adding N2O to the silicon nitride LPCVD gas makes silicon oxynitride, which can provide the passivation and mechanical properties of the nitride and the low dielectric constant and low stress of the oxide. Silicon oxynitride films are used in MEMS and memory devices and also as anti-reflection layers. The thermal expansion coefficient and refractive index can be tuned by varying the process parameters. For example, the refractive index can be increased by increasing the nitrogen fraction, temperature, and/or pressure.

  • Typical film thickness: 0.1 - 2 µm
  • Refractive index at 550 nm / 1.5 - 2.0
  • Batch Size: 50 (18 flat zone) or 100 (34 flat zone)
  • Deposition rate: 1.5 - 8 nm/min. 15 - 80 Å/min.
  • Gases: dichlorosilane, ammonia, nitrous oxide
  • Uniformity: < 5%
  • Deposition Temperature: 770 - 910 °C

Applications: optical waveguides, variable TEC and refractive index, passivation, anti-reflection layers.

LPCVD Processes