Three dimensional integration of waveguides in bulk silicon

We demonstrated the ability to achieve three-dimensional (3D) vertical stacking of waveguides in bulk silicon using proton beam irradiation with electrochemical etching in hydrofluoric acid. With low fluence irradiation, the ion beam acts to selectively stop etching only at the end-of-range, resulting in a silicon core that is embedded in porous silicon cladding. By using the well-defined ion path, we are able to build a 2 and 3 level waveguide systems with single and double energy irradiation through a patterned mask respectively. This means more devices can be packed densely on a single chip for greater functionality and economic returns.

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