Semiconductor structure, semiconductor device with air spacers, and method for fabricating the same
A semiconductor device is provided, which includes a substrate, a first dielectric layer, a conductive layer, and an insulating capping layer. The first dielectric layer is disposed on the substrate. The conductive layer is disposed on the first dielectric layer. The conductive layer comprises a plurality of conductive wires. The insulating capping layer is disposed on the conductive layer, and configured to enclose a plurality of first gaps between the conductive wires to form a plurality of air spacers.
1 . A semiconductor device, comprising:
a substrate;
a first dielectric layer, disposed on the substrate;
a conductive layer, disposed on the first dielectric layer, wherein the conductive layer comprises a plurality of conductive wires disposed on and in contact with a top surface of the first dielectric layer; and
an insulating capping layer, disposed on and in contact with top surfaces of the conductive wires of the conductive layer, and configured to enclose a plurality of first gaps between the conductive wires to form a plurality of air spacers, wherein top openings of the air spacers are coplanar with the top surfaces of the conductive wires and are enclosed by the insulating capping layer;
a first insulating layer having a horizontal portion in contact with the top surface of the first dielectric layer and a vertical portion in contact with a lateral surface of one of the conductive wires, wherein the vertical portion of the first insulating layer is located between one of the conductive wires and one of the air spacers; and
a second dielectric layer disposed on and in contact with the horizontal portion of the first insulating layer, such that the horizontal portion of the first insulating layer is positioned between the first dielectric layer and the second dielectric layer;
wherein bottom openings of the air spacers are enclosed by a top surface of the second dielectric layer, such that a height of each of the air spacers is less than a thickness of each of the conductive wires;
wherein a top surface of the vertical portion of the first insulating layer and the top surfaces of the conductive wires are coplanar with each other and are in contact with the insulating capping layer.
2 . The semiconductor device of claim 1 , further comprising a conductive element disposed on the substrate and adjacent to the first dielectric layer, wherein at least one of the conductive wires is in contact with a top surface of the conductive element.
3 . The semiconductor device of claim 2 , wherein the top surface of the first dielectric layer is coplanar with the top surface of the conductive element.
4 . The semiconductor device of claim 1 , further comprising a second insulating layer, disposed on the second dielectric layer, and filling a plurality of second gaps of the second dielectric layer along lateral directions, wherein each of the air spacers is located between the second insulating layer and the vertical portion of the first insulating layer, such that each of the air spacers is enclosed by the insulating capping layer, the first insulating layer, the second dielectric layer, and the second insulating layer, wherein a top surface of the second insulating layer is in contact with the insulating capping layer.
5 . The semiconductor device of claim 4 , wherein the second insulating layer, the first insulating layer, and the second dielectric layer above a first top surface of the conductive layer are polished.
6 . The semiconductor device of claim 5 , wherein the top openings of the air spacers are coplanar with the top surface of the second insulating layer, such that the height of each of the air spacers is equal to a thickness of the second insulating layer.
7 . The semiconductor device of claim 6 , wherein the second insulating layer, the first insulating layer, and the second dielectric layer are polished using a chemical mechanical polishing process.
8 . The semiconductor device of claim 3 , wherein the second dielectric layer comprises silicon oxide.
9 . The semiconductor device of claim 4 , wherein the insulating capping layer, the first insulating layer, and the second insulating layer are made of a first insulating material.
10 . The semiconductor device of claim 9 , wherein the first insulating material comprises silicon nitride.
11 . The semiconductor device of claim 4 , wherein each of the air spacers is located above the second dielectric layer and the horizontal portion of the first insulating layer.
12 . A semiconductor structure, comprising:
a substrate;
a first dielectric layer, disposed on the substrate;
a plurality of conductive wires, disposed on in contact with a top surface of the first dielectric layer;
a plurality of air spacers, disposed at a plurality of first gaps between the conductive wires along lateral directions of the conductive wires;
a first insulating layer having a horizontal portion in contact with the top surface of the first dielectric layer and a vertical portion in contact with a lateral surface of one of the conductive wires, wherein the vertical portion of the first insulating layer is located between the one of the conductive wires and one of the air spacers;
a second dielectric layer disposed on and in contact with the horizontal portion of the first insulating layer, such that the horizontal portion of the first insulating layer is positioned between the first dielectric layer and the second dielectric layer; and
a second insulating layer disposed on the second dielectric layer, wherein each of the air spacers is located above the second dielectric layer and the horizontal portion of the first insulating layer;
wherein top openings of the air spacers are coplanar with first top surfaces of the conductive wires while bottom openings of the air spacers are enclosed by a top surface of the second dielectric layer, such that a height of each of the air spacers is less than a thickness of each of the conductive wires;
wherein a top surface of the vertical portion of the first insulating layer and the top surfaces of the conductive wires are coplanar with each other.
13 . The semiconductor structure of claim 12 wherein each of the air spacers is located between the second insulating layer and the vertical portion of the first insulating layer, such that each of the air spacers is enclosed by the first insulating layer, the second dielectric layer, and the second insulating layer.
14 . The semiconductor structure of claim 13 , wherein the second insulating layer, the first insulating layer, and the second dielectric layer above the first top surfaces of the conductive wires are polished.
15 . The semiconductor structure of claim 14 , wherein a width of each of the air spacers is equal to a distance between the second insulating layer and the vertical portion of the first insulating layer.
16 . The semiconductor structure of claim 15 , further comprising:
an insulating capping layer, disposed on the first top surfaces of the conductive wires to enclose the top openings the air spacers.