Patent ID: 8415185

Claim:
A process for fabricating an optical slot waveguide on silicon, comprising the steps of: deposition of a thin film of single-crystal silicon on a substrate covered with a buried insulating layer, and subsequently uniform deposition of an insulating or semi-insulating layer on the silicon film, excavation over the entire thickness of this insulating or semi-insulating layer of two openings having vertical sidewalls separated by a narrow gap constituting an insulating or semi-insulating vertical wall extending along a path which is the desired path for the slot waveguide, and epitaxial growth of single-crystal silicon in the openings wherein, before the uniform deposition of the insulating or semi-insulating layer, a local thermal oxidation is carried out over the entire depth of the thin single-crystal silicon film in order to form an insulating oxidized strip extending along the path of the vertical wall, beneath and either side of said wall over the entire length of the path, so that the insulating vertical wall that will subsequently be formed is not adjacent to the thin single-crystal silicon film.