CORNERSTONE is an open access Silicon Photonics rapid prototyping foundry based in the UK.

The prototyping platform utilises industrially-compatible deep-UV projection lithography to enable seamless scaling-up to production volumes via your favourite commercial foundry, but also retains device level innovation capability and flexibility in its process flows, making it ideal for researchers to try innovative designs, or to evaluate new photonic circuits.

This process flexibility and license free, open source model is what differentiates CORNERSTONE from other foundries.


Currently, CORNERSTONE offers 3 different silicon-on-insulator platforms via a multi-project-wafer service for active and passive devices:

  • 220 nm Si / 2 µm BOX
  • 340 nm Si / 2 µm BOX
  • 500 nm Si / 3 µm BOX

Furthermore, as a result of market demand for platforms that support additional wavelengths beyond traditional telecoms, CORNERSTONE is delighted to announce 3 exciting new silicon-based technology platforms, 2 new integration platforms and a DUV lithography service, all available from the summer of 2021. The new platforms are:

  • Silicon nitride
  • Germanium-on-silicon
  • Suspended silicon
  • Electronic-photonic integration via flip-chip bonding
  • Light source integration via pick-and-place
  • DUV lithography