Fabrication of Photonic Wire and Crystal Circuits in Silicon-on-Insulator Using 193-nm Optical Lithography

TLDR

Silicon‑on‑insulator technology offers high‑index contrast that enables wavelength‑scale compact photonic circuits. The study reports fabrication of silicon‑on‑insulator photonic circuits using CMOS processing and demonstrates the suitability of high‑resolution lithography and dry‑etch techniques for mass production. By switching from 248‑nm to 193‑nm lithography and improving dry etching, the authors achieved a wider process window, better linearity, and reduced proximity effects, and used this process to characterize propagation and bending loss. Measurements show a propagation loss of 2.7 dB/cm for 500‑nm wires and an excess bending loss of 0.013 dB/90° at 5‑µm radius, confirming the process’s suitability for mass‑produced photonic integrated circuits.

Abstract

High-index contrast silicon-on-insulator technology enables wavelength-scale compact photonic circuits. We report fabrication of photonic circuits in silicon-on-insulator using complementary metal-oxide-semiconductor processing technology. By switching from advanced optical lithography at 248 to 193 nm, combined with improved dry etching, a substantial improvement in process window, linearity, and proximity effect is achieved. With the developed fabrication process, propagation and bending loss of photonic wires were characterized. Measurements indicate a propagation loss of 2.7 dB/cm for 500-nm photonic wire and an excess bending loss of 0.013 dB/90deg bend of 5-mum radius. Through this paper, we demonstrate the suitability of high resolution optical lithography and dry etch processes for mass production of photonic integrated circuits.