The impacts of fabrication error in Si wire-waveguides on spectral variation of coupled resonator optical waveguides

We experimentally investigate the impacts of fabrication error in Si wire-waveguides on the spectral variation of 5th-order coupled resonator optical waveguides (CROWs). In the fabrication of these waveguide devices, 40-nm-node CMOS technology with ArF immersion lithography was used. The characterization of the CROWs was done by using an automatic optical wafer-level probing system. As for the fabrication errors in 440-nm-wide/220-nm-thick waveguides, standard deviations in waveguide cross-sectional size for a single 300-mm wafer were confirmed to be 0.83 nm in width and 0.24 nm in height. The fabricated CROWs in a single wafer exhibited quite similar resonant peak shapes to each other, and also showed a remarkably small standard deviation of 0.67 nm in resonant wavelength, which agrees with the theoretical estimation from the fabrication error. These results show that the precise process control using ArF immersion lithography technology is effective to the reproducible device fabrication for wide-bandwidth optical interconnection.

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