Multi-region diffusion barrier containing titanium, silicon and nitrogen
The disclosed technology generally relates to semiconductor structures and their fabrication, and more particularly to diffusion barrier structures containing Ti, Si, N and methods of forming same. A method of forming an electrically conductive diffusion barrier comprises providing a substrate in a reaction chamber and forming a titanium silicide (TiSi) region on the substrate by alternatingly exposing the substrate to a titanium-containing precursor and a first silicon-containing precursor. The method additionally comprises forming a titanium silicon nitride (TiSiN) region on the TiSi region by alternatingly exposing the substrate to a titanium-containing precursor, a nitrogen-containing precursor and a second silicon-containing precursor. The method can optionally include, prior to forming the TiSi region, forming a titanium nitride (TiN) region by alternatingly exposing the substrate to a titanium-containing precursor and a nitrogen-containing precursor.
1 . A method of forming an electrically conductive diffusion barrier, the method comprising:
providing a substrate comprising an exposed silicon surface formed of monocrystalline silicon or polycrystalline silicon in a reaction chamber;
forming a first region directly on the exposed silicon surface by alternatingly exposing the substrate to a titanium precursor and a nitrogen precursor;
forming a second region over the first region by exposing the substrate to a silicon precursor; and
forming a third region comprising TiSiN over the second region by alternatingly exposing the substrate to the titanium precursor and the nitrogen precursor, wherein exposures to the titanium precursor and the nitrogen precursor immediately follow each other without exposing the substrate to the silicon precursor therebetween, thereby forming TiN, followed by exposing the substrate to the silicon precursor,
wherein the first, second and third regions are formed in situ in the reaction chamber.
2 . The method of claim 1 , wherein a combined thickness of the first to third regions of the diffusion barrier does not exceed 10 nm.
3 . The method of claim 1 , wherein forming the first region comprises exposing the exposed silicon surface to the titanium precursor as a first precursor contacting the exposed silicon surface.
4 . The method of claim 1 , wherein forming the second region further comprises exposing the substrate to the titanium precursor prior to exposing the substrate to the silicon precursor.
5 . The method of claim 1 , wherein the first to third regions are formed at a temperature of about 550° C. to about 700° C.
6 . The method of claim 1 , wherein forming the first to third regions comprises thermally reacting respective precursors without using plasma.
7 . The method of claim 1 , wherein forming the third region comprises alternatingly exposing the substrate to the titanium precursor immediately followed by exposing the substrate to the nitrogen precursor without exposing the substrate to the silicon precursor therebetween, followed by exposing the substrate to the silicon precursor.
8 . The method of claim 1 , wherein the first region forms a TiN region.
9 . The method of claim 1 , wherein the third region forms a TiSiN region.
10 . A method of forming an electrically conductive diffusion barrier, the method comprising:
providing a substrate comprising an exposed silicon surface formed of monocrystalline silicon or polycrystalline silicon in a reaction chamber;
forming a first region directly on the exposed silicon surface by exposing the substrate first to a titanium precursor, followed by alternatingly exposing the substrate to a nitrogen precursor and the titanium precursor;
forming a second region over the first region by exposing the substrate to a silicon precursor; and
forming a third region comprising TiSiN over the second region by alternatingly exposing the substrate to the titanium precursor and the nitrogen precursor to form TiN, followed by exposing the substrate to the silicon precursor,
wherein a combined thickness of the first to third regions does not exceed 10 nm.
11 . The method of claim 10 , wherein the silicon precursor comprises SiH 2 Cl 2 , SiHCl 3 or SiCl 4 .
12 . The method of claim 10 , wherein forming the second region further comprises exposing the substrate to the titanium precursor prior to exposing the substrate to the silicon precursor.
13 . The method of claim 10 , wherein the first to third regions are formed at a temperature of about 550° C. to about 700° C.
14 . The method of claim 10 , wherein forming the first to third regions comprises thermally reacting respective precursors without using plasma.
15 . The method of claim 10 , further comprising depositing tungsten directly on the third region.
16 . The method of claim 10 , wherein forming the third region comprises exposing the substrate to the nitrogen precursor immediately followed by exposing the substrate to the titanium precursor without exposing the substrate to the silicon precursor therebetween.
17 . A method of forming an electrically conductive diffusion barrier, the method comprising:
providing a substrate comprising an exposed silicon surface formed of monocrystalline silicon or polycrystalline silicon in a reaction chamber;
forming a first region directly on the exposed silicon surface of the substrate by alternatingly exposing the substrate to a titanium precursor and a nitrogen precursor;
forming a second region over the first region by exposing the substrate to a silicon precursor; and
forming a third region comprising TiSiN over the second region by alternatingly exposing the substrate to the titanium precursor and the nitrogen precursor to form TiN, followed by exposing the substrate to the silicon precursor,
wherein forming the first to third regions comprises thermally reacting respective precursors without using plasma.
18 . The method of claim 17 , wherein a combined thickness of the first to third regions does not exceed 10 nm.
19 . The method of claim 17 , wherein forming the first region comprises exposing the exposed silicon surface to the titanium precursor as a first precursor contacting the exposed silicon surface.
20 . The method of claim 17 , wherein forming the second region further comprises exposing the substrate to the titanium precursor prior to exposing the substrate to the silicon precursor.
21 . The method of claim 18 , wherein the silicon precursor comprises SiH 2 Cl 2 , the titanium precursor comprises TiCl 4 and the nitrogen precursor comprises NH 3 .
22 . The method of claim 17 , wherein forming the third region comprises exposing the substrate to the nitrogen precursor immediately followed by exposing the substrate to the titanium precursor without exposing the substrate to the silicon precursor therebetween.