Using electrical resistance asymmetries to infer the geometric shapes of foundry patterned nanophotonic structures

TL;DR

This paper demonstrates that electrical resistance measurements can be used to infer the three-dimensional geometry of silicon nanophotonic structures, enabling better understanding of fabrication processes and potential improvements in nanofabrication accuracy.

Contribution

It introduces a novel method to reconstruct 3D geometries of nanophotonic structures from electrical resistance data, bridging a gap in metrology for silicon photonics fabrication.

Findings

Electrical resistance asymmetries correlate with geometric features.

Method successfully infers 3D geometries from foundry data.

Potential sources of error identified and discussed.

Abstract

While silicon photonics has leveraged the nanofabrication tools and techniques from the microelectronics industry, it has also inherited the metrological methods from the same. Photonics fabrication is inherently different from microelectronics in its intrinsic sensitivity to 3D shape and geometry, especially in a high-index contrast platform like silicon-on-insulator. In this work, we show that electrical resistance measurements can in principle be used to infer the geometry of such nanophotonic structures and reconstruct the micro-loading curves of foundry etch processes. We implement our ideas to infer 3D geometries from a standard silicon photonics foundry and discuss some of the potential sources of error that need to be calibrated out to improve the reconstruction accuracy.