Video Presentation: Reactive Ion Beam Etching of Lithium Niobate for Photonic Integrated Circuits
Susanne Hartmann's presentation at the Photonics Spectra Integrated Photonics Summit 2026 explains how reactive ion beam etching (RIBE) addresses sidewall effects such as footing, fencing, and trenching in thin-film lithium niobate (TFLN) processing, thereby enabling lower optical losses in photonic integrated circuits.
Few forces are shaping photonics right now as much as the compute and bandwidth demands of artificial intelligence (AI). A single AI query can consume up to ten times the power of a standard web search. Inside data centers, tens of thousands of racks need to communicate over cable runs as long as two kilometers, incurring ohmic losses, heat dissipation, and electromagnetic interference along the way.
Photonics offers a way out: photons traveling through glass fibers and waveguides avoid these losses almost entirely and by superposition of different wavelengths allow many data channels to run in parallel on a single circuit.
At Photonics Spectra Integrated Photonics Summit 2026, Susanne Hartmann presented on how these Photonic Integrated Circuits (PICs) are manufactured, with a focus on lithium niobate (LiNbO3, LN) or Thin-Film Lithium Niobate (TFLN). She explains how ion beam etching, particularly its reactive variant (RIBE), which introduces fluorine-containing gases such as CHF3 into the argon plasma, can improve both etch rate and material selectivity compared to pure ion beam milling (IBE).
A key part of the talk addressed the typical challenges of ion beam etching LiNbO3:
- Fencing – redeposited LN material along mask edges
- Footing – a non-horizontal base caused by shallow etch angles (shadowing effect)
- Trenching – small trenches near the structure caused by ions reflected off the mask at steep angles
- Mask erosion – common with photoresist masks, leading to edge artifacts
- Curtaining – mask roughness transferred onto the LN surface
The solution to these challenges is to adjust the gas flow, optimize the tilt angle, and use a two-step etch process.
