Process Development of Low-Loss LPCVD Silicon Nitride Waveguides on 8-Inch Wafer

Silicon nitride is a material compatible with CMOS processes and offers several advantages, such as wide transparent window, large forbidden band gap, negligible two-photon absorption, excellent nonlinear properties, smaller thermo-optic coefficient than silicon. Therefore, it has received significant attention in the field of silicon photonics recent years. The preparation waveguides using low-pressure chemical vapor deposition methods results lower loss better process repeatability. However, due to higher temperature process, when thickness film exceeds 300 nm on an 8-inch wafer, prone cracking high stress generated by film. Limited this stress, waveguide devices are typically developed wafers 4 inches or less. In work, we successfully fabricated 400 nm-thick wafer Damascene method similar for copper interconnects demonstrated propagation losses only 0.157 dB/cm at 1550 0.06 1580 nm.