Multi-tiered semiconductor waveguide and multi-tiered waveguide heater

An integrated chip, comprising:

• a base dielectric layer;
• a multi-tiered semiconductor waveguide layer over the base dielectric layer, the multi-tiered semiconductor waveguide layer having a first waveguide tier having a first width at a first height over the base dielectric layer, a second waveguide tier having a second width, greater than the first width, at a second height, less than the first height, over the base dielectric layer, and a third waveguide tier having a third width, greater than the second width, at a third height, less than the second height, over the base dielectric layer;
• a cladding layer conformally overlying the multi-tiered semiconductor waveguide layer;
• a multi-tiered conductive heater layer conformally overlying the cladding layer, the multi-tiered conductive heater layer spaced apart from the multi-tiered semiconductor waveguide layer by the cladding layer, the multi-tiered conductive heater layer having a first heater tier over the first waveguide tier, the multi-tiered conductive heater layer having a pair of second heater tiers at the first height, over the second waveguide tier, and on opposite sides of the first waveguide tier, and the multi-tiered conductive heater layer having a pair of third heater tiers at the second height, over the third waveguide tier, and on opposite sides of the second waveguide tier;
• a pair of first contacts over and coupled to the multi-tiered conductive heater layer along the first heater tier;
• a pair of second contacts over and coupled to the multi-tiered conductive heater layer along one of the pair of second heater tiers;
• a pair of third contacts over and coupled to the multi-tiered conductive heater layer along the other of the pair of second heater tiers;
• a pair of fourth contacts over and coupled to the multi-tiered conductive heater layer along one of the pair of third heater tiers;
• and
• a pair of fifth contacts over and coupled to the multi-tiered conductive heater layer along the other of the pair of third heater tiers.

A method for forming an integrated chip, the method comprising:

• etching a semiconductor waveguide layer to form a multi-tiered semiconductor waveguide from the semiconductor waveguide layer, the multi-tiered semiconductor waveguide having a first waveguide tier having a first width at a first height over a base dielectric layer, the multi-tiered semiconductor waveguide having a second waveguide tier having a second width, greater than the first width, at a second height, less than the first height, over the base dielectric layer, the multi-tiered semiconductor waveguide having a pair of protrusions protruding upward on opposite sides of the first and second waveguide tiers;
• depositing a cladding layer conformally over the multi-tiered semiconductor waveguide;
• depositing a conductive heater layer conformally over the cladding layer to form a multi-tiered conductive heater over the cladding layer and the multi-tiered semiconductor waveguide, the multi-tiered conductive heater having a first heater tier over the first waveguide tier, the multi-tiered conductive heater having a pair of second heater tiers at the first height, over the second waveguide tier, and on opposite sides of the first waveguide tier, wherein the pair of protrusions of the multi-tiered semiconductor waveguide are spaced from the multi-tiered conductive heater on opposite sides of the multi-tiered conductive heater;
• depositing an upper dielectric layer over the multi-tiered conductive heater;
• etching the upper dielectric layer to form a first contact opening, a second contact opening, and a third contact opening in the upper dielectric layer, the first contact opening over the first heater tier, the second contact opening and the third contact opening over the pair of second heater tiers, respectively;
• depositing a metal over the upper dielectric layer and in the first contact opening, the second contact opening, and the third contact opening to form a first contact in the first contact opening, a second contact in the second contact opening, and a third contact in the third contact opening, the first contact coupled to the multi-tiered conductive heater at the first heater tier, the second contact and the third contact coupled to the multi-tiered conductive heater at the pair of second heater tiers, respectively;
• and
• forming a fourth contact on one of the pair of protrusions of the multi-tiered semiconductor waveguide and coupled to the multi-tiered semiconductor waveguide at the one of the pair of protrusions.