Systematic Nonuniformity Analysis of Amorphous Silicon-on-Insulator Photonic Microring Resonators

Low temperature deposited hydrogenated amorphous silicon (a-Si:H) is a promising material to fabricate compact photonic-electronic integrated circuits (PICs) in multiple layers. However, high refractive index contrast (HIC) photonic circuits are challenging in fabrication and even smallest deviations of the material quality or manufacturing have huge impact on the system performance. We present a systematic study of intrawafer nonuniformity and wafer-to-wafer reproducibility of low-loss aSi:H and investigate the spectral disorder of photonic microring resonators (MRRs). Photonic MRRs in various spatial configurations, different mask resolutions, and in multiplexed arrangement were fabricated and the spectral disorder in resonance position was examined in within-chip, chip-to-chip, and wafer-to-wafer spectral transmission measurements. The microrings exhibit chip-averaged wafer ranges less than 7.5 nm over 16 chips a 1.5 × 1.5 cm
²
with standard deviations of 220 pm in average for short range systems distanced by a few 100 μm. The spatially normalized wafer median of the resonance wavelength spread was determined to be lower 0.7 nm/cm on three wafers. The results demonstrate that a-Si:H PICs are suitable for large-scale integration and the manufacturing quality facilitates low-cost and high throughput assembly-line processing.