Smooth titanium nitride layers and methods of forming the same
The disclosed technology generally relates to forming a titanium nitride layer, and more particularly to forming by atomic layer deposition a titanium nitride layer on a seed layer. In one aspect, a semiconductor structure comprises a semiconductor substrate comprising a non-metallic surface. The semiconductor structure additionally comprises a seed layer comprising silicon (Si) and nitrogen (N) conformally coating the non-metallic surface and a TiN layer conformally coating the seed layer. Aspects are also directed to methods of forming the semiconductor structures.
1. A method of forming a thin film comprising titanium nitride (TiN), the method comprising:
providing a semiconductor substrate comprising a non-metallic surface;
forming on the non-metallic surface a seed layer by atomic layer deposition (ALD), wherein the seed layer is a SiN seed layer; and
forming on the seed layer a TiN layer by ALD,
wherein forming the seed layer comprises alternatingly exposing the semiconductor substrate to one or more cycles, each of the cycles comprising an exposure to a Si precursor and an exposure to a N precursor, thereby forming the SiN seed layer,
wherein the seed layer is distinct from the TiN layer and continuously covers the non-metallic surface with a thickness of about 0.5 nm to about 5 nm, and
wherein a root mean square surface roughness of a stack comprising the TiN layer formed on the seed layer is less than about 8% of a thickness of the stack.
2. The method of claim 1 , wherein a surface roughness of the stack is about the same or lower relative to a surface roughness of a reference TiN layer that is formed using the same ALD as that used to form the TiN layer, but directly formed on a reference non-metallic surface that is the same as the non-metallic surface without a seed layer formed thereon.
3. The method of claim 1 , wherein forming the seed layer and the TiN layer comprises forming by thermal ALD.
4. The method of claim 1 , wherein the non-metallic surface comprises one or both of a semiconductor surface and an insulator surface.
5. The method of claim 1 , wherein forming one or both of the seed layer and the TiN layer on the seed layer comprise growing in a layer-by-layer growth mode.
6. The method of claim 1 , wherein forming one or both of the seed layer and the TiN layer on the seed layer comprise exposing the semiconductor substrate to a Si precursor selected from the group consisting of SiH 4 , Si 2 H 6 , SiH 2 Cl 2 , SiH 3 Cl, Si 2 Cl 6 and Si 3 Cl 8 .
7. The method of claim 1 , wherein the seed layer is at least partially amorphous.
8. The method of claim 1 , wherein the semiconductor substrate comprises a trench or a via comprising an inner surface comprising the non-metallic surface, and wherein forming the thin film comprises conformally lining the inner surface.
9. The method of claim 1 , wherein an electrical resistivity of the TiN layer formed on the seed layer is about the same or lower relative to an electrical resistivity of a reference TiN layer that is formed using the same ALD as that used to form the TiN layer, but directly formed on a reference non-metallic surface that is the same as the non-metallic surface without a seed layer formed thereon.
10. A method of forming a thin film comprising titanium nitride (TiN), the method comprising:
providing a semiconductor substrate comprising a non-metallic surface;
forming on the non-metallic surface a seed layer by atomic layer deposition (ALD), wherein the seed layer is a SiN seed layer; and
forming on the seed layer a TiN layer by ALD,
wherein forming the seed layer comprises exposing the semiconductor substrate to a Si precursor as a first non-nitrogen precursor and further exposing the semiconductor substrate to a N precursor, thereby forming the SiN seed layer,
wherein the seed layer is distinct from the TiN layer and continuously covers the non-metallic surface with a thickness of about 0.5 nm to about 5 nm, and
wherein an electrical resistivity of a stack comprising the TiN layer formed on the seed layer is less than about 200 μΩ-cm.
11. The method of claim 10 , wherein forming the seed layer and the TiN layer comprises forming by thermal ALD.
12. The method of claim 10 , wherein the electrical resistivity of the stack is about the same or lower relative to a reference TiN layer that is formed using the same ALD as that used to form the TiN layer, but directly formed on a reference non-metallic surface that is the same as the non-metallic surface without a seed layer formed thereon.
13. The method of claim 10 , wherein a ratio of thicknesses of the seed layer and the TiN layer is such that the TiN layer has an electrical resistivity less than about 200 μΩ-cm.
14. The method of claim 10 , wherein a thickness ratio between the TiN layer formed on the seed layer and the seed layer exceeds 5.
15. The method of claim 10 , wherein a surface roughness of the TiN layer formed on the seed layer is about the same or lower relative to a surface roughness of a reference TiN layer that is formed using the same ALD as that used to form the TiN layer, but directly formed on a reference the non-metallic surface that is the same as the non-metallic surface without a seed layer formed thereon.