Semiconductor device and method of forming the same
Provided are a semiconductor device and a method of forming the same. The semiconductor device includes a semiconductor device. The semiconductor device includes a substrate including a plurality of fins, a plurality of semiconductor nanosheets stacked on the plurality of fins, a plurality of gate stacks wrapping the plurality of semiconductor nanosheets, an isolation structure around the plurality of fins, and a separator structure on the isolation structure to separate the plurality of gate stacks from each other. The separator structure includes a body and a cap on the body. The cap includes a first portion and a second portion. Sidewalls and bottom of the second portion is wrapped by the first portion.
1 . A semiconductor device, comprising:
a substrate comprising fins;
semiconductor nanosheets stacked on the fins;
an isolation structure around the fins;
a separator structure on the isolation structure, wherein the separator structure comprises:
a body; and
a cap disposed on the body, wherein the cap comprises a first cap portion and a second cap portion connected to the first cap portion, the second cap portion extends laterally from the first cap portion in a direction different from a stacking direction of the semiconductor nanosheets, and the first cap portion is thicker than the second cap portion along the stacking direction of the semiconductor nanosheets, and a first top surface of the first cap portion is higher than a second top surface of the second cap portion along the stacking direction of the semiconductor nanosheets.
2 . The semiconductor device of claim 1 , wherein a top surface of the body is covered by the second cap portion.
3 . The semiconductor device of claim 1 , wherein the cap comprises:
a first dielectric portion; and
a second dielectric portion, wherein sidewalls and bottom of the second dielectric portion is wrapped by the first dielectric portion, an interface is between the first dielectric portion and the second dielectric portion, and the interface comprises a first segment; a second segment; and a third segment, wherein the first segment and the third segment extend longitudinally, and the second segment extends laterally and is connected to bottom ends of the first segment and the third segment.
4 . The semiconductor device of claim 3 , wherein a minimum horizontal distance between the first segment and an outer sidewall of the cap decreases from bottom to top.
5 . The semiconductor device of claim 3 , wherein a minimum horizontal distance between the third segment and an outer sidewall of the cap decreases from bottom to top.
6 . The semiconductor device of claim 3 , wherein a top width of the second dielectric portion of the cap is greater than a bottom width of the second dielectric portion of the cap.
7 . The semiconductor device of claim 1 , wherein outer sidewalls of the cap substantially align with outer sidewalls of the body.
8 . The semiconductor device of claim 3 , wherein the first segment and the third segment are arcs or inclined lines.
9 . The semiconductor device of claim 3 , wherein the second dielectric portion of the cap is free of voids or seams.
10 . A semiconductor device, comprising:
a substrate comprising fins;
semiconductor nanosheets stacked on the fins;
an isolation structure around the fins;
source/drain (S/D) features on the fins;
a separator structure on the isolation structure to separate the source/drain (S/D) features from each other, wherein the separator structure comprises:
a body in contact with the isolation structure; and
a cap disposed on the body, wherein the cap comprises a first cap portion and a second cap portion connected to the first cap portion, the second cap portion extends laterally from the first cap portion in a direction orthogonal to a stacking direction of the semiconductor nanosheets, and a first top surface of the first cap portion is higher than a second top surface of the second cap portion along the stacking direction of the semiconductor nanosheets.
11 . The semiconductor device of claim 10 , wherein the cap comprises a first dielectric portion and a second dielectric portion, an interface is between the first dielectric portion and the second dielectric portion, and the interface comprises:
a first segment;
a second segment; and
a third segment, wherein the first segment and the third segment extend longitudinally, and the second segment extends laterally and is connected to bottom ends of the first segment and the third segment.
12 . The semiconductor device of claim 10 , wherein the second top surface of the second cap portion is located at a height level between the first top surface of the first cap portion and a top surface of the body.
13 . The semiconductor device of claim 10 , wherein the cap comprises a bottom portion disposed on the body and a top portion disposed on the bottom portion, and the top portion of the cap is narrower than the bottom portion of the cap.
14 . The semiconductor device of claim 10 , further comprising an etch stop layer on the source/drain (S/D) features and the separator structure, and sidewalls and a top surface of the cap are covered by the etch stop layer.
15 . The semiconductor device of claim 14 , wherein a portion of the etch stop layer is laterally sandwich between the separator structure and the source/drain (S/D) features.
16 . A method of forming a semiconductor device, comprising:
providing a substrate comprising a plurality of fins;
forming a plurality of semiconductor nanosheets stacked on the plurality of fins;
forming an isolation structure around the plurality of fins; and
forming a separator structure on the isolation structure, wherein the forming the separator structure comprises:
forming a body; and
forming a cap on the body, wherein the cap comprises a first cap portion and a second cap portion connected to the first cap portion, the second cap portion extend laterally from the first cap portion in a direction orthogonal to a stacking direction of the semiconductor nanosheets, and a first top surface of the first cap portion is higher than a second top surface of the second cap portion along the stacking direction of the semiconductor nanosheets.
17 . The method of claim 16 ,
further comprising forming a gate stack over a portion of the semiconductor nanosheets and a portion of the separator structure.
18 . The method of claim 17 , further comprising performing a removal process to remove end portions of the semiconductor nanosheets, and a portion of the cap not covered by the gate stack, thereby forming a first cap portion covered by the gate stack and the second cap portion uncovered by the gate stack.
19 . The method of claim 16 , further comprising forming a first dielectric material on the body, and a second dielectric material over the first dielectric material to form the cap.
20 . The method of claim 19 ,
wherein sidewalls and bottom of the second dielectric material is wrapped by the first dielectric material and a width of the first dielectric material contacting sidewalls of the second dielectric material continuously decreases from a top surface of the body in a direction towards a top end of the cap.