Ultra-low temperature silicon nitride photonic integration platform

Area of Science:

• Materials Science
• Optical Engineering
• Nanotechnology

Background:

• Integrated photonics requires materials with low optical loss and controllable stress.
• Traditional deposition methods often require high temperatures, limiting substrate compatibility and process integration.

Purpose of the Study:

• To develop high-quality silicon nitride (SiNx) films at ultra-low temperatures for photonic applications.
• To demonstrate the viability of ultra-low temperature SiNx as a platform for integrated photonic devices.

Main Methods:

• Deposition of SiNx films using inductively coupled plasma chemical vapor deposition (ICP-CVD) at 75 °C.
• Fabrication of microcavities using alternating SiNx/SiO2 layers for distributed Bragg reflectors (DBRs).
• Fabrication of microring resonators using electron-beam lithography (EBL) and plasma etching.

Main Results:

• Achieved SiNx films with controllable low stress and low optical loss at 75 °C.
• Demonstrated crack-free microcavities (11.5 μm thickness, 49 layers) showcasing excellent stress control.
• Fabricated microring resonators with an average waveguide loss of 0.79 ± 0.22 dB/cm (1550-1600 nm) for radii > 40 μm.

Conclusions:

• Ultra-low temperature SiNx deposition is a viable method for producing high-quality films for photonics.
• The developed SiNx material platform enables the fabrication of complex integrated photonic structures.
• This technology holds promise for various photonic integration applications requiring low loss and low stress.