Forming dual metallization interconnect structures in single metallization level
Techniques are provided to fabricate metallic interconnect structures in a single metallization level, wherein different width metallic interconnect structures are formed of different metallic materials to eliminate or minimize void formation in the metallic interconnect structures. For example, a semiconductor device includes an insulating layer disposed on a substrate, and a first metallic line and a second metallic line formed in the insulating layer. The first metallic line has a first width, and the second metallic line has a second width which is greater than the first width. The first metallic line is formed of a first metallic material, and the second metallic line is formed of a second metallic material, which is different from the first metallic material. For example, the first metallic material is cobalt or ruthenium, and the second metallic material is copper.
1. A method, comprising:
forming an insulating layer on a substrate;
patterning the insulating layer to form a plurality of trench openings in the insulating layer, wherein the plurality of trench openings comprises a first trench opening having a first width, and a second trench opening having a second width, which is greater than the first width;
depositing a first layer of liner material to form a first liner layer on sidewall and bottom surfaces of the first and second trench openings;
depositing a first layer of metallic material to fill the first trench opening with metallic material, wherein the metallic material within the first trench opening comprises a first metallic line;
forming an etch protection layer to protect the metallic material within the first trench opening;
performing an etch process to remove a portion of the first layer of metallic material within the second trench opening, while the etch protection layer protects the metallic material within the first trench opening from being etched during the etch process; and
depositing a second layer of metallic material to fill the second trench opening with metallic material, wherein the metallic material within the second trench opening comprises a second metallic line;
wherein the metallic material of the second layer of metallic material is different from the metallic material of the first layer of metallic material;
wherein forming the etch protection layer to protect the metallic material within the first trench opening, comprises:
performing a planarizing process to remove an overburden portion of the first layer of metallic material disposed on an upper surface of the insulating layer;
depositing a conformal layer of etch protection material; and
patterning the conformal layer of etch protection material to remove a portion of the conformal layer of etch protection material which covers the second trench opening and expose the portion of the first layer of metallic material within the second trench opening.
2. The method of claim 1 , wherein the first layer of metallic material comprises cobalt.
3. The method of claim 1 , wherein the first layer of metallic material comprises ruthenium.
4. The method of claim 1 , wherein the second layer of metallic material comprises copper.
5. The method of claim 1 , wherein the second width is at least two times greater than the first width.
6. The method of claim 5 , wherein the first width is about 20 nm or less.
7. The method of claim 1 , wherein the first layer of liner material comprises one of tantalum, titanium, tantalum nitride, and titanium nitride.
8. The method of claim 1 , further comprising depositing a second layer of liner material to form a second liner layer on the first liner layer on the sidewall and bottom surfaces of the second trench opening, prior to depositing the second layer of metallic material.
9. The method of claim 8 , further comprising depositing a metallic seed layer on the second liner layer in the second trench opening, prior to depositing the second layer of metallic material.
10. The method of claim 1 , wherein performing the etch process comprises performing a wet etch process with an etch chemistry that is configured to etch the portion of the first layer of metallic material within the second trench opening selective to the etch protection layer and the first liner layer.
11. The method of claim 1 , wherein the insulating layer comprises an interlayer dielectric (ILD) layer of a back-end-of-line (BEOL) structure.
12. The method of claim 1 , wherein the insulating layer comprises a pre-metal dielectric layer of a middle-of-line (MOL) structure.