Structures and methods for stress and gap mitigation in integrated optics microelectromechanical systems

A method of fabricating an optical channel waveguide comprising:

• depositing a lower cladding comprising a first silicon dioxide layer of a first predetermined thickness upon a substrate;
• depositing and patterning a core of the optical channel waveguide comprising silicon nitride of a second predetermined thickness and a first predetermined width upon the lower cladding;
• depositing an upper cladding comprising a second silicon dioxide layer of a third predetermined thickness atop the core and lower cladding;
• and
• annealing the resulting structure within a nitrogen environment under first predetermined conditions;
• wherein
• the annealing results in a refractive index of the optical channel waveguide varying in a non-step wise manner from the silicon nitride core to the silicon dioxide cladding in both vertical and horizontal directions relative to the substrate.

A method of fabricating an optical channel waveguide comprising:

• depositing a lower cladding comprising a first silicon dioxide layer of a first predetermined thickness upon a substrate;
• depositing and patterning a core of the optical channel waveguide comprising silicon nitride of a second predetermined thickness and a first predetermined width upon the lower cladding;
• depositing an upper cladding comprising a second silicon dioxide layer of a third predetermined thickness atop the core and lower cladding;
• annealing the resulting structure within a nitrogen environment under first predetermined conditions;
• and
• performing one or more further sequences, each further sequence comprising:
• depositing a further upper cladding comprising a third silicon dioxide layer of a fourth predetermined thickness atop the core and lower cladding;
• and
• annealing the resulting structure within a nitrogen environment under second predetermined conditions.

A method of fabricating an optical channel waveguide comprising:

• depositing a lower cladding comprising a first silicon dioxide layer of a first predetermined thickness upon a substrate;
• depositing and patterning a core of the optical channel waveguide comprising silicon nitride of a second predetermined thickness and a first predetermined width upon the lower cladding;
• depositing an upper cladding comprising a second silicon dioxide layer of a third predetermined thickness atop the core and lower cladding;
• annealing the resulting structure within a nitrogen environment under first predetermined conditions;
• and
• depositing a further upper cladding comprising a third silicon dioxide layer of a fourth predetermined thickness atop the core and lower cladding;
• wherein
• the annealing step results in a layer of varying silicon oxynitride surrounding a predetermined portion of the core of the optical channel waveguide;
• the upper cladding deposited prior to the annealing step is a thin layer;
• and
• the further upper cladding is a thick layer.

A method of fabricating an optical channel waveguide comprising:

• depositing a lower cladding comprising a first silicon dioxide layer of a first predetermined thickness upon a substrate;
• depositing and patterning a core of the optical channel waveguide comprising silicon nitride of a second predetermined thickness and a first predetermined width upon the lower cladding;
• depositing an upper cladding comprising a second silicon dioxide layer of a third predetermined thickness atop the core and lower cladding;
• annealing the resulting structure within a nitrogen environment under first predetermined conditions;
• and
• performing one or more additional processing sequences, each additional processing sequence comprising:
• depositing a further upper cladding comprising a further silicon dioxide layer of a predetermined thickness atop structure resulting from the previous processing;
• and
• annealing the resulting structure within a nitrogen environment under another set of predetermined conditions.

A method of fabricating an optical channel waveguide comprising:

• depositing a lower cladding comprising a first silicon dioxide layer of a first predetermined thickness upon a substrate;
• depositing and patterning a core of the optical channel waveguide comprising silicon nitride of a second predetermined thickness and a first predetermined width upon the lower cladding;
• depositing an upper cladding comprising a second silicon dioxide layer of a third predetermined thickness atop the core and lower cladding;
• annealing the resulting structure within a nitrogen environment under first predetermined conditions;
• and
• performing one or more additional processing sequences prior to depositing a final upper cladding layer, each additional processing sequence comprising:
• depositing a further upper cladding comprising a further silicon dioxide layer of a predetermined thickness atop structure resulting from the previous processing;
• and
• annealing the resulting structure within a nitrogen environment under another set of predetermined conditions;
• and
• depositing the final upper cladding layer.

A method of fabricating an optical channel waveguide comprising:

• depositing a lower cladding comprising a first silicon dioxide layer of a first predetermined thickness upon a substrate;
• depositing and patterning a core of the optical channel waveguide comprising silicon nitride of a second predetermined thickness and a first predetermined width upon the lower cladding;
• depositing an upper cladding comprising a second silicon dioxide layer of a third predetermined thickness atop the core and lower cladding;
• annealing the resulting structure within a nitrogen environment under first predetermined conditions;
• and
• performing one or more additional processing sequences prior to depositing a final layer, each additional processing sequence comprising:
• depositing a further upper cladding comprising a further silicon dioxide layer of a predetermined thickness atop structure resulting from the previous processing;
• and
• annealing the resulting structure within a nitrogen environment under another set of predetermined conditions;
• and
• applying the final layer with a spin-on planarization process.

A method of fabricating an optical channel waveguide comprising:

• depositing a lower cladding comprising a first silicon dioxide layer of a first predetermined thickness upon a substrate;
• depositing and patterning a core of the optical channel waveguide comprising silicon nitride of a second predetermined thickness and a first predetermined width upon the lower cladding;
• depositing an upper cladding comprising a second silicon dioxide layer of a third predetermined thickness atop the core and lower cladding;
• and
• annealing the resulting structure within a nitrogen environment under first predetermined conditions;
• wherein
• the annealing impacts:
• each lateral sidewall of the core with the upper cladding;
• a lower surface of the core with the lower cladding;
• and
• an upper surface of the core with the upper cladding;
• such that the propagation loss of the resulting optical waveguide is reduced for both TE and TM polarisations.