Spacer structure for semiconductor device
The present disclosure describes an inner spacer structure for a semiconductor device and a method for forming the same. The method for forming the inner spacer structure in the semiconductor device can include forming a vertical structure over a substrate, forming a gate structure over a portion of the vertical structure, exposing sidewalls of the portion of the vertical structure, forming multiple spacers over the sidewalls of the portion of the vertical structure, and forming a void in each of the multiple spacers.
1. A semiconductor structure, comprising:
a substrate;
a vertical structure over the substrate, wherein the vertical structure comprises:
a first portion having one or more channel layers separated from each other; and
a second portion having a source/drain region in contact with the one or more channel layers;
a gate structure between each of the one or more channel layers; and
a plurality of inner spacers disposed between the gate structure and the source/drain region, wherein each of the plurality of inner spacer comprises a void isolated from the source/drain region and a curved surface adjacent to the void and in contact with the source/drain region.
2. The semiconductor structure of claim 1 , wherein each of the plurality of inner spacers is disposed between adjacent channel layers of the one or more channel layers.
3. The semiconductor structure of claim 1 , wherein each of the plurality of inner spacers further comprises:
an oxide layer; and
a dielectric layer, wherein the oxide layer and the dielectric layer surround the void.
4. The semiconductor structure of claim 1 , wherein the void is between adjacent channel layers of the one or more channel layers.
5. The semiconductor structure of claim 1 , wherein:
the first portion of the vertical structure comprises a base region under the one or more channel regions; and
the gate structure is between the base region and the one or more channel regions, wherein one or more of the plurality of inner spacers are between the base region and the one or more channel regions.
6. A semiconductor device, comprising:
a substrate;
a vertical structure formed on the substrate;
a stack of channel regions in the vertical structure, wherein the vertical structure comprises source/drain regions electrically coupled to the stack of channel regions;
a gate structure surrounding each of the channel regions in the stack of channel regions; and
inner spacers on opposite sidewalls of each gate structure, each inner spacer comprising first and second dielectric layers and a void between the first and second dielectric layers, wherein an interface between the first and second dielectric layers is perpendicular to a top surface of the substrate, and wherein the interface is substantially coplanar with a side surface of the void.
7. The semiconductor device of claim 6 , wherein the void is filled with air.
8. The semiconductor device of claim 6 , wherein the void has a rectangular shape.
9. The semiconductor device of claim 6 , wherein the void has length, width, and height dimensions in a range of about 1 nm to about 8 nm.
10. The semiconductor device of claim 6 , wherein the first dielectric layer comprises a low-k material having a dielectric constant less than about 3.5.
11. The semiconductor device of claim 6 , wherein the inner spacers are located between the gate structures and the source/drain regions.
12. The semiconductor device of claim 6 , wherein the sidewall of the void is parallel to another sidewall of the void.
13. A transistor, comprising:
a substrate;
a stack of nanostructures formed on the substrate, the nanostructures comprising channel regions alternating with gate structures;
source/drain regions formed on the substrate, the source/drain regions coupled to the channel regions; and
spacers formed adjacent to the gate structures, each of the spacers comprising first and second insulators and encapsulating a void structure, wherein a top of first insulator is aligned with a top of the second insulator along a direction parallel to a top surface of the substrate.
14. The transistor of claim 13 , wherein the first and second insulators comprise at least two different dielectric materials.
15. The transistor of claim 14 , wherein the void structures are formed between the at least two different dielectric materials.
16. The transistor of claim 14 , wherein the at least two different dielectric materials include one or more of an oxide material, a nitride material, and a low-k dielectric material.
17. The transistor of claim 13 , wherein the void structures have rectangular cross sections.
18. The transistor of claim 13 , wherein each of the void structures is surrounded on three sides by the first insulator and on one side by the second insulator.
19. The transistor of claim 13 , wherein the void structures have a dielectric constant substantially equal to 1.0.
20. The transistor of claim 13 , wherein an interface between the first insulator and the source/drain regions is curved.