Semiconductor structure and method of fabricating the same
View Patent ↗A semiconductor structure includes a substrate and a metal layer disposed in the substrate. The semiconductor structure includes a dielectric layer disposed over the metal layer. The semiconductor structure further includes a semiconductor layer disposed over the dielectric layer, where the metal layer extends across the semiconductor layer. The semiconductor layer includes a two-dimensional grating coupler including a plurality of scattering elements disposed in the semiconductor layer and a pair of tapered structures extending laterally from the two-dimensional grating coupler.
1 . A semiconductor structure, comprising:
a substrate;
a metal layer;
a dielectric layer disposed over the metal layer; and
a semiconductor layer disposed over the dielectric layer, the metal layer extending across the semiconductor layer, the semiconductor layer including:
a two-dimensional grating coupler including a plurality of scattering elements disposed in the semiconductor layer; and
a pair of tapered structures extending laterally from the two-dimensional grating coupler;
wherein the metal layer extends over an entirety of a region over which the two-dimensional grating coupler and the pair of tapered structures are disposed,
wherein the scattering elements are arranged in an apodized pattern.
2 . The semiconductor structure of claim 1 , wherein the apodized pattern includes first curved grating lines extending along a first direction and second curved grating lines extending along a second direction in a top view, the first direction and the second direction being perpendicular to one another.
3 . The semiconductor structure of claim 2 , wherein a top surface of each scattering element is configured with a polygon shape having a first dimension along a third direction and a second dimension along a fourth direction, each of the third direction and the fourth direction being different from the first direction and the second direction, and wherein the first dimension gradually varies along each of the first direction and the second direction.
4 . The semiconductor structure of claim 3 , wherein the first dimension gradually increases along each of the first direction and the second direction towards each of the tapered structures.
5 . The semiconductor structure of claim 3 , wherein a spacing between adjacent scattering elements gradually decreases along each of the first direction and the second direction towards each of the tapered structures.
6 . The semiconductor structure of claim 3 , wherein the second dimension remains constant along each of the first direction and the second direction.
7 . The semiconductor structure of claim 1 , wherein a top surface of each scattering element is configured with a polygon shape having at least four sides.
8 . The semiconductor structure of claim 7 , wherein the at least four sides each include a straight portion and an elliptical portion.
9 . The semiconductor structure of claim 1 , wherein adjacent scattering elements are configured with different height to form a step profile in a cross-sectional view.
10 . The semiconductor structure of claim 1 , wherein the semiconductor layer further includes a pair of waveguides each extending laterally from a corresponding tapered structure.
11 . A semiconductor structure, comprising:
a first semiconductor layer;
a metal layer;
a dielectric layer disposed over the metal layer; and
a second semiconductor layer disposed over the dielectric layer, including:
a grating coupler having a plurality of scattering elements arranged in an apodized pattern;
a pair of tapered structures extending from the grating coupler; and
a pair of waveguides, wherein each tapered structure couples the grating coupler to a corresponding waveguide;
wherein the metal layer extends over an entirety of a region over which the grating coupler, the pair of tapered structures, and the pair of waveguides are disposed.
12 . The semiconductor structure of claim 11 , wherein the apodized pattern includes first curved lines arranged along a first direction and second curved lines arranged along a second direction perpendicular to the first direction, and wherein each scattering element is positioned at an intersection of each of the first curved lines and each of the second curved lines.
13 . The semiconductor structure of claim 12 , wherein a spacing between two adjacent scattering elements varies along each of the first direction and the second direction.
14 . The semiconductor structure of claim 11 , wherein a top surface of each scattering element is configured with a rhomboid shape.
15 . The semiconductor structure of claim 14 , wherein each side of the rhomboid shape includes a curved portion.
16 . The semiconductor structure of claim 11 , wherein a top surface of each scattering element is configured with an elongated octagon shape.
17 . A semiconductor structure, comprising:
a first semiconductor layer;
a metal layer;
a dielectric layer disposed over the metal layer;
a second semiconductor layer disposed over the dielectric layer, including a two-dimensional grating coupler formed by two single-polarization grating couplers disposed substantially perpendicular to each other, wherein each single-polarization grating coupler includes a set of curved grating lines;
a pair of tapered structures extending from the two-dimensional grating coupler;
wherein the metal layer extends over an entirety of a region over which the two-dimensional grating coupler and the pair of tapered structures are disposed.
18 . The semiconductor structure of claim 17 , further comprising an optical fiber configured to apply an optical input to the semiconductor structure at an incident angle.
19 . The semiconductor structure of claim 17 , wherein at least one set of the curved grating lines are each configured with an elliptical shape.
20 . The semiconductor structure of claim 17 , wherein the two-dimensional grating coupler includes a plurality of scattering elements disposed in the second semiconductor layer, each scattering element having a top surface configured with a rhomboid shape.