Additive core subtractive liner for metal cut etch processes
An additive core subtractive liner method is described for forming electrically conductive contacts. The method can include forming a first trench in an first dielectric layer to expose a first portion of a metal liner, and filling said first trench with a second dielectric layer. A metal cut trench is formed in the second dielectric layer. A portion of the metal liner exposed by the metal cut trench is removed with a subtractive method. The method continues with filling the metal cut trench with a dielectric fill, and replacing the remaining portions of the second dielectric layer with an additive core conductor to provide contacts to remaining portions of the metal liner.
1. A method of forming an electrically conductive structure to a device comprising:
forming a first trench in a first dielectric layer to expose a first portion of a metal liner;
filling said first trench with a second dielectric layer;
forming a metal cut trench in the second dielectric layer;
removing a portion of the metal liner exposed by the metal cut trench with a subtractive method;
filling the metal cut trench with a dielectric fill; and
replacing remaining portions of the second dielectric layer with an additive core conductor to provide contacts to remaining portions of the metal liner that were not removed by the subtractive method.
2. The method of claim 1 , wherein the first dielectric layer is an interlevel dielectric layer and the second dielectric layer is an organic planarization layer (OPL).
3. The method of claim 1 , wherein the metal liner is in contact with source/drain regions of a semiconductor device.
4. The method of claim 1 , wherein the metal liner is a layer within a replacement gate structure of a replacement metal gate process, wherein a high-k gate dielectric is underlying the metal liner in a gate cavity.
5. The method of claim 1 , wherein the metal liner is a component of an interconnect during back end of the line (BEOL) processing.
6. The method of claim 1 , wherein the subtractive method comprises a wet etch having a composition selected from the group consisting of a first mixture of ammonium hydroxide, hydrogen peroxide and water, a second mixture of hydrochloric acid, hydrogen peroxide and water, a sulfuric peroxide mixture and a combination thereof.
7. The method of claim 1 , wherein the subtractive method for removing the portion of the metal liner that is removed by the subtractive method is an atomic layer etch process.
8. The method of claim 1 , wherein said filling the metal cut trench comprises a low temperature deposition process.
9. The method of claim 1 , wherein said replacing said remaining portions of the second dielectric layer with with said additive core conductor to provide contacts comprises:
removing the remaining portions of the second dielectric layer selective to the first dielectric layer, and the dielectric fill to provide openings to the remaining portions of the metal liner;
filling the openings to the remaining portions of the metal liner with an electrically conductive material; and
planarizing the electrically conductive material to provide the additive core conductor.
10. The method of claim 9 , wherein the electrically conductive material filling the openings to the remaining portions of the metal liner comprises a conformal metal liner and a bulk metal core fill.
11. The method of claim 1 , wherein said forming the metal cut trench in the second dielectric layer comprises a subtractive etch process that forms a tapered sidewall for the metal cut trench, wherein said tapered sidewall is provided by an addition of a polymeric additive to the subtractive etch process in a patterning etch chemistry for the subtractive etch process.
12. The method of claim 1 , wherein said removing the portion of the metal liner exposed by the metal cut trench with the subtractive method comprising implanting chemical species into the exposed portion of the metal liner, wherein the chemical species increase at least one of etch directionality and etch rate, wherein said chemical species is selected from the group consisting of oxygen, a halogen, a noble gas atom, nitrogen and a combination thereof.