Monolithic splitter using re-entrant poly silicon waveguides

A method for forming an electromagnetic waveguide, comprising:

• forming a dummy gate electrode over a substrate;
• forming spacers along sidewalls of the dummy gate electrode, wherein the spacers include a re-entrant profile;
• removing the dummy gate electrode;
• and
• depositing a conductive body between the spacers with a conformal deposition process, wherein a void is formed within the conductive body during the deposition of the conductive body.

An electromagnetic waveguide, comprising:

• a first spacer;
• a second spacer;
• a first portion of a conductive body formed along sidewalls of the first and second spacer and over a substrate on which the electromagnetic waveguide is formed;
• and
• a second portion of the conductive body formed between an upper portion of the first portion of the conductive body, wherein the first portion of the conductive body and the second portion of the conductive body define a void through the electromagnetic waveguide.

A method of forming an electromagnetic waveguide, comprising:

• forming a dummy gate electrode;
• forming spacers on sidewalls of the dummy gate electrode;
• removing the dummy gate electrode;
• depositing a first portion of a conductive body along sidewall surfaces of the spacers and over a top surface of a substrate on which the electromagnetic waveguide is formed with a conformal deposition process;
• depositing a sacrificial material over the first portion of the conductive body with a non-conformal deposition process;
• depositing a second portion of a conductive body over the sacrificial material;
• and
• removing the sacrificial material to form a void defined by the first portion of the conductive body and the second portion of the conductive body.