標準晶圓製程下之微共振腔整合設計

Silicon photonics has been widely studied as the next generation integratedcircuits and applied in applications such as computing, communication, andsensing. Traditionally, on-chip waveguides provide ways for optical signaltransferring from fibers to integrated processors. By utilizing the maturecomplementary metal-oxide-semiconductor (CMOS) technique, integratedphotonics shows small footprint, low-cost fabrication, and the capability to bringlab-bench-top models to portable devices in the real world. For all the integratedcomponents, waveguide-based resonators play a critical role in manyperspectives, ranging from modulators, filters, detectors, switchers, and on-chipnarrow-linewidth lasers. Traditionally, resonators with high quality factor (Q) forapplications like nonlinear and quantum photonics require delicate processes.For instance, electron beam (E-beam) lithography is needed to provide elegant,nanometer-scale patterning while user-defined trenches for strain release arealso widely used to yield crack-free resonator. In addition, U- or V-grooves areneeded to make interconnection between fiber and on-chip waveguide, especiallyfor the stability at high-input power. Although these processes have been wellestablished, they still limit the process flexibility for future integration with hybridsemiconductor platforms.In this proposal, we introduce several ideas to simplify the process flow andalleviate the fabrication difficulties of making high quality microresonators. Forthe 1st phase, we aim to integrate silicon nitride-based resonator with the I-linestepper lithography, providing a cost-effective, fast, and large-scale process forwaveguide patterning. Resonators with quality factor (Q) 10^5~10^6 will bedemonstrated. In addition, a groove-first method will be included to providehighly stable fiber-to-waveguide coupling. This process integration helps tosimplify the groove-etching process and shows the potentials to inherently form anano-taper at the groove edge with hyper-resolution exceeding the I-line limit.This naturally formed taper can improve the coupling efficiency from the fiber tothe on-chip waveguide. For the 2nd phase, to compensate the weak couplingfrom the limited fabricated gap between the bus waveguide and resonator, asingle-side taper is proposed to enhance the coupling to the resonator within Ilineresolution limit (300 nm ~ 400 nm). This design not only helps to yield overcouplingfor nonlinear and quantum applications but also provides criticalcoupling for linear applications with a moderate Q (Q<10^5) from the I-linestepper process. Last, these integrated processes will also be applied to III-V(Gallium nitride)-based waveguide resonators. This work provides a compact,cost-effective, large-scale, and simple fabrication process for photonicsintegration.