Simulation-guided optimization of CMOS-compatible silicon nitride micro-ring resonators: design, fabrication, and wafer-level evaluation

Silicon nitride micro-ring resonators are critical components in photonic integrated circuits due to their compact footprint, high optical quality, and compatibility with standard complementary metal-oxide-semiconductor fabrication processes. This study presents a comprehensive design, fabrication, and performance evaluation of silicon nitride-based micro-ring resonators, with a focus on optimizing the optical quality factor and analyzing key metrics such as free spectral range, extinction ratio, and coupling efficiency. Here we demonstrate a simulation-guided, wafer-scale workflow that delivers repeatable, high- Q resonators across 200 mm substrates. Finite-difference time-domain simulations were used to guide the design, exploring variations in waveguide width, ring radius, and coupling gap. Devices were fabricated using both low-pressure and plasma-enhanced chemical vapor deposition methods, followed by wafer-level optical characterization. The best devices reached an intrinsic quality factor of 4.2 × 10 5 and a free spectral range of 1.2 nm at 852 nm, with <5% die-to-die spread; narrower 400 nm gaps boosted Q by ∼30 % without sacrificing extinction ratio. The results emphasize the importance of careful design and process control to achieve high performance in scalable, complementary metal-oxide-semiconductor-compatible photonic platforms. These quantified gains translate to >18 months projected lifetime extension in visible–NIR sensing modules, paving the way for mass-produced Si 3 N 4 photonic chips. These findings support the integration of optimized micro-ring resonators into applications such as optical sensing and communication, and offer design guidelines for further improvement in device yield and performance consistency.