Surface roughness reduction for photonics using high-temperature implantation

A method of forming a waveguide, comprising:

• providing a workpiece including a buried oxide atop a substrate, and a shallow trench isolation formed over the buried oxide;
• forming a contact etch stop layer (CESL) over the shallow trench isolation;
• patterning the CESL to expose an upper surface of the shallow trench isolation in a waveguide target area;
• forming an oxide layer over the CESL, including over the upper surface of the shallow trench isolation in the waveguide target area;
• directing ions into an upper surface of a dielectric film formed atop the oxide layer using a high-temperature ion implant to decrease a surface roughness of the upper surface of the dielectric film;
• and
• patterning a waveguide from the dielectric film after the high-temperature ion implant, wherein the waveguide is formed over the waveguide target area.

A method for reducing surface roughness of a waveguide, the method comprising:

• providing a workpiece including a buried oxide atop a substrate, and a shallow trench isolation formed over the buried oxide;
• forming a contact etch stop layer (CESL) over the shallow trench isolation;
• patterning the CESL to expose an upper surface of the shallow trench isolation in a waveguide target area;
• forming an oxide layer over the CESL, including over the upper surface of the shallow trench isolation in the waveguide target area;
• patterning the waveguide from a dielectric film formed atop the oxide layer, wherein the waveguide is formed over the waveguide target area;
• and
• directing ions into an upper surface of the waveguide using a high-temperature ion implant to reduce the surface roughness of the upper surface of the waveguide.