Photonic silicon-insulator-silicon modulator and methods for forming the same

A method of fabricating a photonic device, comprising:

• etching a silicon-on-insulator substrate to form a first terminal comprising silicon and a waveguide structure connected with the first terminal;
• forming a cladding dielectric layer around the first terminal and the waveguide structure;
• forming a capacitor dielectric layer over the first terminal, wherein forming the capacitor dielectric layer comprises:
• forming a gate oxide layer over the first terminal, wherein forming the gate oxide layer consumes the silicon of the first terminal;
• forming a SiON layer by introducing nitrogen into the gate oxide layer;
• and
• annealing the SiON layer;
• forming a polysilicon layer over the capacitor dielectric layer;
• and
• etching the polysilicon layer and the capacitor dielectric layer to form a second terminal comprising polysilicon and an insulator comprising a portion of the capacitor dielectric layer disposed between the first terminal and the second terminal.

A method of fabricating a photonic device, comprising:

• providing a silicon-on-insulator substrate;
• forming a core comprising:
• etching the silicon-on-insulator substrate to form a silicon portion of the core;
• forming an oxide layer over the silicon portion of the core, wherein forming the oxide layer comprises:
• forming a gate oxide layer over the first terminal, wherein forming the gate oxide layer consumes the silicon of the first terminal;
• forming a SiON layer by introducing nitrogen into the gate oxide layer;
• and
• annealing the SiON layer;
• and
• forming a polysilicon portion of the core over the oxide layer;
• forming a cladding dielectric layer around the core;
• wherein the silicon portion extends to a first terminal and the polysilicon portion extends to a second terminal, wherein the oxide layer is disposed between the silicon portion and the polysilicon portion.