Contacts formed with self-aligned cuts
Methods of fabricating structures that include contacts coupled with a source/drain region of a field-effect transistor. Source/drain regions are formed adjacent to a temporary gate structure. In one process, a sacrificial layer is disposed over the source/drain regions and a dielectric pillar is formed in the sacrificial layer between the source/drain regions, followed by deposition of a fill material, replacement of the temporary gate structure with a functional gate structure, and removal of the fill material. In another process, the fill material is formed first and the temporary gate structure is replaced by a functional gate structure; following removal of the fill material, a sacrificial layer is disposed over the source/drain regions and a dielectric pillar is formed in the sacrificial layer between the source/drain regions. A conductive layer having separate portions contacting the separate source/drain regions is formed, with the dielectric pillar separating the portions of the conductive layer.
1. A method comprising:
forming a first source/drain region and a second source/drain region adjacent to a temporary gate structure;
forming a sacrificial layer over the first source/drain region and the second source/drain region;
etching a trench in the sacrificial layer that is disposed between the first source/drain region and the second source/drain region;
depositing a first dielectric material in the trench to form a dielectric pillar between the first source/drain region and the second source/drain region;
after depositing the first dielectric material in the trench, forming a fill layer over the first source/drain region and the second source/drain region;
after forming the fill layer, replacing the temporary gate structure with a functional gate structure;
after replacing the temporary gate structure with the functional gate structure, removing the fill layer; and
forming a conductive layer having a first portion contacting the first source/drain region and a second portion contacting the second source/drain region,
wherein the dielectric pillar separates the first portion of the conductive layer from the second portion of the conductive layer.
2. The method of claim 1 wherein the sacrificial layer is composed of an organic planarization layer material.
3. The method of claim 1 further comprising:
before depositing the first dielectric material in the trench, depositing a dielectric liner on sidewalls of the trench.
4. The method of claim 1 wherein etching the trench in the sacrificial layer comprises:
forming a lithography stack over the sacrificial layer;
forming an opening in the lithography stack to expose a portion of the sacrificial layer; and
etching the exposed portion of the sacrificial layer.
5. The method of claim 1 wherein etching the trench in the sacrificial layer comprises:
etching an upper portion of the trench in the sacrificial layer, the upper portion exposing a portion of the first source/drain region and a portion of the second source/drain region;
forming a dielectric spacer on sidewalls of the upper portion of the trench; and
etching a lower portion of the trench in the sacrificial layer, the dielectric liner material protecting remaining portions of the sacrificial layer arranged over the first source/drain region and the second source/drain region.
6. The method of claim 5 wherein etching the lower portion of the trench comprises:
anisotropically etching the sacrificial layer disposed between the first source/drain region and the second source/drain region; and
isotropically etching the sacrificial layer disposed below the portion of the first source/drain region and below the portion of the second source/drain region.
7. The method of claim 5 further comprising:
depositing a dielectric liner on sidewalls of the lower portion of the trench, on the exposed portion of the first source/drain region, and on the exposed portion of the second source/drain region.
8. The method of claim 7 wherein the dielectric liner and the dielectric spacer are each composed of a second dielectric material.
9. The method of claim 5 further comprising:
before forming the dielectric spacer, etching an outer portion of the first source/drain region and an outer portion of the second source/drain region.