Optical waveguide apparatus and method of fabrication thereof

A semiconductor structure, comprising:

• a buried oxide layer;
• a first dielectric layer disposed over the buried oxide layer;
• a first waveguide feature disposed in the first dielectric layer;
• a second dielectric layer disposed over the first dielectric layer and the first waveguide feature;
• a plurality of contact features disposed in the second dielectric layer
• a third dielectric layer disposed over the second dielectric layer;
• and
• a second waveguide feature disposed in the second dielectric layer and the third dielectric layer,
• wherein a top surface of the second waveguide feature is higher than top surfaces of the plurality of contact features,
• wherein a portion of the second waveguide feature vertically overlaps a portion of the first waveguide feature.

A structure, comprising:

• a first doped silicon feature and a second doped silicon feature disposed over a substrate;
• a first metal contact disposed over the first doped silicon feature;
• a first silicide feature sandwiched between the first metal contact and the first doped silicon feature;
• a second metal contact disposed over the second doped silicon feature;
• a second silicide feature sandwiched between the second metal contact and the second doped silicon feature;
• a first waveguide feature disposed between the first doped silicon feature and the second doped silicon feature;
• and
• a second waveguide feature disposed between the first metal contact and the second metal contact,
• wherein the second waveguide feature is disposed on the first waveguide feature,
• where a top surface of the second waveguide feature is higher than top surfaces of the first metal contact and the second metal contact.