Gate cut with integrated etch stop layer
View Patent ↗A method of forming a power rail to semiconductor devices comprising removing a portion of the gate structure forming a gate cut trench separating a first active region of fin structures from a second active region of fin structures. A conformal etch stop layer is formed in the gate cut trench. A fill material is formed on the conformal etch stop layer filling at least a portion of the gate cut trench. The fill material has a composition that is etched selectively to the conformal etch stop layer. A power rail is formed in the gate cut trench. The conformal etch stop layer obstructs lateral etching during forming the power rail to substantially eliminate power rail to gate structure shorting.
1. A method of forming a power rail to semiconductor devices comprising:
providing a first active semiconductor region and a second active semiconductor region;
forming a gate structure extending from the first active region to the second active region;
removing a portion of the gate structure forming a gate cut trench separating the first active region from the second active region;
forming a conformal etch stop layer in the gate cut trench;
forming a fill material on the conformal etch stop layer filling at least a portion of the gate cut trench, wherein the fill material has a composition that is etched selectively to the conformal etch stop layer; and
forming a power rail in the gate cut trench, wherein the conformal etch stop layer obstructs lateral etching during forming the power rail to substantially eliminate power rail to gate structure shorting.
2. The method of claim 1 , wherein the first active region comprises at least one first fin structure, and the second active region comprises at least one second fin structure.
3. The method of claim 2 , wherein the forming the gate structure extending from the first active region to the second active region comprises:
forming a dummy polysilicon gate structure over the channel portions of the at least one first fin structure, wherein first source and drain regions of the at least one first fin structure are present on opposing sides of the dummy polysilicon gate structure, and second source and drain regions of the at least one second fin structure are present on opposing sides of the dummy polysilicon gate structure; and
forming a gate sidewall spacer on the sidewalls of the gate structure.
4. The method of claim 1 , wherein said removing the portion of the gate structure comprises an anisotropic etch process.
5. The method of claim 1 , wherein the gate cut trench is present through an interlevel dielectric layer extending between adjacent portions of the gate structure that have been separated by the gate cut trench.
6. The method of claim 1 , wherein said forming the conformal etch stop layer comprises depositing the conformal etch stop layer on sidewalls of the gate cut trench and a base of the gate cut trench.
7. The method of claim 1 , wherein forming a conformal etch stop layer comprises hafnium oxide (HfO 2 ).
8. The method of claim 6 , wherein the fill material is composed of a nitride.
9. The method of claim 8 , wherein the fill material is deposited to fill an entirety of the gate cut trench.
10. The method of claim 1 , wherein said forming the power rail in the gate cut trench comprises:
forming an etch mask exposing a portion of the gate cut trench;
etching the fill material to provide a power rail opening, wherein the conformal etch stop layer obstructs lateral etching during said etching of the fill material to substantially eliminate power rail to gate structure shorting; and
depositing an electrically conductive material for the power rail in the power rail opening.
11. A method of forming a power rail to semiconductor devices comprising:
providing a first active semiconductor region and a second active semiconductor region;
forming a sacrificial gate structure extending from the first active region to the second active region;
removing a portion of the sacrificial gate structure forming a gate cut trench separating the first active region from the second active region; forming a conformal etch stop layer in the gate cut trench;
forming a fill material on the conformal etch stop layer filling at least a portion of the gate cut trench, wherein the fill material has a composition that is etched selectively to the conformal etch stop layer;
substituting the sacrificial gate structure with a functional gate structure; and
forming a power rail in the gate cut trench, wherein the conformal etch stop layer obstructs lateral etching during forming the power rail to substantially eliminate power rail to gate structure shorting.
12. The method of claim 11 , wherein the sacrificial gate structure is composed of polysilicon.
13. The method of claim 11 , wherein said forming the conformal etch stop layer comprises depositing the conformal etch stop layer on sidewalls of the gate cut trench and a base of the gate cut trench.
14. The method of claim 11 , wherein forming a conformal etch stop layer comprises hafnium oxide (HfO 2 ).
15. The method of claim 11 , wherein the fill material is composed of a nitride.
16. The method of claim 11 , wherein said forming the power rail in the gate cut trench comprises:
forming an etch mask exposing a portion of the gate cut trench;
etching the fill material to provide a power rail opening, wherein the conformal etch stop layer obstructs lateral etching during said etching of the fill material to substantially eliminate power rail to sacrificial gate structure shorting; and
depositing an electrically conductive material for the power rail in the power rail opening.
17. The method of claim 11 , wherein said substituting the sacrificial gate structure with a functional gate structure comprises:
removing the sacrificial gate structure with a selective etch to provide a functional gate structure opening;
forming at least one gate dielectric in the functional gate structure opening; and
forming at least one gate conductor on the at least one gate dielectric in the functional gate structure opening.