Subnanometer Linewidth Uniformity in Silicon Nanophotonic Waveguide Devices Using CMOS Fabrication Technology

TLDR

The study employs wavelength‑selective devices—ring resonators, Mach‑Zehnder interferometers, and arrayed waveguide gratings—fabricated on silicon‑on‑insulator wafers using 193 nm or 248 nm optical lithography and dry etching to evaluate device nonuniformity within and between chips. Using high‑volume CMOS tools, the authors achieved subnanometer linewidth uniformity, with 2 nm lithography and 2.6 nm after dry etch across a 200 mm wafer, and demonstrated <0.6 nm control within chips and <2 nm chip‑to‑chip, highlighting the need for high‑resolution 193 nm lithography.

Abstract

We report subnanometer linewidth uniformity in silicon nanophotonics devices fabricated using high-volume CMOS fabrication tools. We use wavelength-selective devices such as ring resonators, Mach-Zehnder interferometers, and arrayed waveguide gratings to assess the device nonuniformity within and between chips. The devices were fabricated using 193 or 248 nm optical lithography and dry etching in silicon-on-insulator wafer technology. Using 193 nm optical lithography, we have achieved a linewidth uniformity of 2 nm (after lithography) and 2.6 nm (after dry etch) over 200 mm wafer. Furthermore, with the developed fabrication process, using wavelength-selective devices, we have demonstrated a linewidth control better than 0.6 nm within chip and better than 2 nm chip-to-chip. The necessity for high-resolution optical lithography is demonstrated by comparing device nonuniformity between the 248 and 193 nm optical lithography processes.