Junctionless back end of the line via contact
A method of forming an interconnect structure includes providing a first dielectric layer, patterning a wire opening in a first dielectric layer, lining the wire opening with a metal liner and includes filling the wire opening with a first conductive material. The method also includes depositing a first cap on the first dielectric layer, depositing a second dielectric layer, and patterning a via trench in the second dielectric layer. The method also includes depositing a metal liner, removing the metal liner from a via junction, and enlarging the contact area. The method also includes filling the via trench with a second conductive material to form a via.
1. A method of forming an interconnect structure, the method comprising:
providing a first dielectric layer,
patterning a wire opening in a first dielectric layer,
lining the wire opening with a metal liner,
filling the wire opening with a first conductive material,
depositing a first cap on the first dielectric layer to form a first device layer, the first device layer comprising the first dielectric layer and the first cap,
depositing a second dielectric layer on the first device layer,
patterning a via trench in the second dielectric layer, wherein the via trench includes a via junction at the top of the second conductive material,
depositing a metal liner,
removing the metal liner from a via junction,
enlarging the contact area, and
filling the via trench with a second conductive material to form a via.
2. The method of claim 1 , wherein filling the via trench with a second conductive material comprises seeding the second conductive material from a surface of the first conductive material.
3. The method of claim 1 , the method further comprising planarizing the structure after filling the via trench with a second conductive material.
4. The method of claim 1 , wherein the first conductive material and the second conductive material are the same material.
5. The method of claim 4 , wherein the first conductive material and the second conductive material are copper.
6. The method of claim 1 , wherein the first dielectric layer and the second dielectric layer are the same material.
7. The method of claim 1 , wherein removing the metal liner from the via junction comprises reactive ion etching.
8. The method of claim 1 , further comprising undercutting the first conductive material with isotropic wet etching before filling the via trench with the second conductive material.
9. A method of forming an interconnect structure, the method comprising:
depositing an interlayer dielectric on a bottom interconnect layer, the bottom interconnect layer comprising a bottom dielectric layer and a first material,
patterning a trench in the interlayer dielectric, the trench extending through the interlayer dielectric to the top of the first material,
depositing a metal liner on the patterned interlayer dielectric,
anisotropically etching the liner to remove the liner from the bottom of the trench,
isotropically etching the structure to remove a portion of the first material, and
depositing a second material to fill the trench.
10. The method of claim 9 , wherein the interlayer dielectric is a dielectric material having a dielectric constant less than 4.
11. The method of claim 9 , wherein the first material and the second material are the same material.
12. The method of claim 11 , wherein the first material and the second material are copper.
13. The method of claim 9 , wherein the second material is a sacrificial material.
14. The method of claim 9 , further comprising depositing a first cap on the bottom interconnect layer.
15. The method of claim 9 , further comprising depositing a second cap on the interlayer dielectric.