Interconnection structures in a semiconductor device and methods of manufacturing the same
Methods of fabricating interconnection structures of a semiconductor device are provided. The method includes, inter alia: forming a first insulation layer on a semiconductor substrate, forming a mold layer having trenches on the first insulation layer, forming a sidewall protection layer including a first metal silicide layer on sidewalls of the trenches, forming second metal lines that fill the trenches, forming upper protection layers on the second metal lines, removing the mold layer after formation of the upper protection layers to provide gaps between second metal lines, and forming a second insulation layer in the gaps and on the upper protection layers. The second insulation layer is formed to include air gaps between the second metal lines. Related interconnection structures are also provided.
1. A method of fabricating interconnection structures of a semiconductor device, the method comprising:
forming a first insulation layer on a semiconductor substrate;
forming a silicon mold layer having trenches on the first insulation layer;
forming a first metal layer covering sidewalls of the trenches;
reacting the first metal layer with the silicon mold layer to form first metal silicide layers acting as sidewall protection layers;
forming second metal lines that fill the trenches;
forming upper protection layers on the second metal lines;
removing the silicon mold layer after formation of the upper protection layers to provide gaps between second metal lines; and
forming a second insulation layer in the gaps and on the upper protection layers,
wherein the second insulation layer is formed to include air gaps between the second metal lines.
2. The method of claim 1 , further comprising forming contact plugs that penetrate the first insulation layer to connect the semiconductor substrate to the second metal lines prior to formation of the silicon mold layer.
3. The method of claim 1 , wherein forming the silicon mold layer includes:
depositing a silicon layer on the first insulation layer; and
patterning the silicon mold layer to form the trenches.
4. The method of claim 3 , wherein forming the first metal layer includes forming a cobalt containing layer that directly contacts sidewalls of the trenches.
5. The method of claim 4 , wherein the cobalt containing layer is formed by depositing a cobalt layer.
6. The method of claim 5 , wherein the cobalt containing layer is formed to extend onto bottom surfaces of the trenches.
7. The method of claim 6 , wherein forming the sidewall protection layers includes annealing the cobalt containing layer and the silicon mold layer to form cobalt silicide layers corresponding to the first metal silicide layers that cover the sidewalls of the trenches, and
wherein portions of the cobalt containing layer on the bottom surfaces of the trenches remain without any reaction during formation of the cobalt silicide layers, thereby functioning as bottom barrier layers.
8. The method of claim 7 , wherein annealing the cobalt containing layer and the silicon mold layer is performed using a rapid thermal annealing (RTA) process at a temperature of about 450° C. to about 800° C.
9. The method of claim 7 , wherein removing the silicon mold layer is performed using a wet etching process that employs a mixture of nitric acid (HNO 3 ), hyfrofluoric acid (HF), and de-ionized water or a chemical solution including ammonium hydroxide (NH 4 OH) as an etchant.
10. The method of claim 1 , wherein forming the second metal lines includes forming copper layers that fill the trenches.