Cobalt-tungsten alloy and method of fabricating the same

Abstract

Disclosed are a cobalt-tungsten alloy and a method of fabricating the same. More particularly, cobalt-tungsten alloy nanowires according to an embodiment are formed using an electroplating method, a grain structure of the cobalt-tungsten alloy nanowires is controlled according to the content of tungsten, and the electrical resistivity of the cobalt-tungsten alloy nanowires can be reduced through annealing.

What is claimed is: 
     
         1 . Cobalt-tungsten alloy nanowires, wherein the cobalt-tungsten alloy nanowires are formed using an electroplating method, a grain structure of the cobalt-tungsten alloy nanowires is controlled according to a content of tungsten, and electrical resistivity of the cobalt-tungsten alloy nanowires is reduced through annealing. 
     
     
         2 . The cobalt-tungsten alloy nanowires according to  claim 1 , wherein a cobalt-tungsten intermetallic compound is formed through the annealing and thus the electrical resistivity is reduced. 
     
     
         3 . The cobalt-tungsten alloy nanowires according to  claim 1 , wherein the intermetallic compound appears at 2θ of 40.70°±0.3°, 43.88°±0.3° and 46.46°±0.3° during x-ray diffraction (XRD) analysis. 
     
     
         4 . The cobalt-tungsten alloy nanowires according to  claim 1 , wherein the annealing is performed at 25° C. to 600° C. 
     
     
         5 . The cobalt-tungsten alloy nanowires according to  claim 1 , wherein the grain structure is controlled to have an amorphous-like structure when the content of tungsten is 25.1 at. %. 
     
     
         6 . The cobalt-tungsten alloy nanowires according to  claim 1 , wherein the grain structure is controlled to have a mixed structure comprising an amorphous-like structure and a polycrystalline structure when the content of tungsten is 15.8 at. % to 19.1 at. %. 
     
     
         7 . The cobalt-tungsten alloy nanowires according to  claim 1 , wherein the content of tungsten is controlled by adjusting at least one of a tungsten precursor concentration and a current density. 
     
     
         8 . The cobalt-tungsten alloy nanowires according to  claim 1 , wherein the cobalt-tungsten alloy nanowires are formed by the electroplating method of using a deionized water-based solution comprising precursors, cobalt sulfate heptahydrate (CoSO 4 .7H 2 O) and sodium tungstate heptahydrate (Na 2 WO 4 .7H 2 O). 
     
     
         9 . The cobalt-tungsten alloy nanowires according to  claim 8 , wherein the deionized water-based solution further comprises boric acid (H 3 BO 3 ) and citric acid (C 6 H 8 O 7 ), as buffers, and sodium citrate tribasic dihydrate (C 6 H 7 Na 3 O 8 ) as an additive. 
     
     
         10 . The cobalt-tungsten alloy nanowires according to  claim 1 , wherein the cobalt-tungsten alloy nanowires are applied in the form of at least one of a barrier and a liner with respect to at least one of a via, contact and metal line comprised in a back end of line (BEOL) layer of a semiconductor device. 
     
     
         11 . The cobalt-tungsten alloy nanowires according to  claim 10 , wherein the cobalt-tungsten alloy nanowires are applied in the form of the barrier and the liner on a metal layer of the metal line. 
     
     
         12 . A method of fabricating cobalt-tungsten alloy nanowires, the method comprising:
 forming cobalt-tungsten (Co—W) alloy nanowires on a nanotemplate using an electroplating method; and   annealing the formed alloy nanowires,   wherein, in the forming, a grain structure of the alloy nanowires is controlled according to a content of tungsten.   
     
     
         13 . The method according to  claim 12 , wherein, in the annealing, a cobalt-tungsten intermetallic compound is formed through the annealing and thus electrical resistivity is reduced. 
     
     
         14 . The method according to  claim 12 , wherein the annealing is performed at 25° C. to 600° C. 
     
     
         15 . The method according to  claim 12 , wherein, in the forming, the content of tungsten is adjusted to 25.1 at. % to control the grain structure of the alloy nanowires to have an amorphous-like structure. 
     
     
         16 . The method according to  claim 12 , wherein, in the forming, the content of tungsten is adjusted to 15.8 at. % to 19.1 at. % to control the grain structure of the alloy nanowires to have an amorphous-like structure. 
     
     
         17 . The method according to  claim 12 , wherein, in the forming, the cobalt-tungsten alloy nanowires are formed using the electroplating method in an environment in which a current density of 1.25 mA/cm 2  to 5.00 mA/cm 2  is applied to simultaneously reduce cobalt and the tungsten. 
     
     
         18 . The method according to  claim 12 , wherein, in the forming, a precursor concentration of the tungsten is adjusted to 0.20 mol L −1  and a current density is adjusted to 5.00 mA/cm 2  to control the content of tungsten. 
     
     
         19 . The method according to  claim 12 , wherein the nanotemplate comprises a polycarbonate membrane (PCM) or anodic aluminum oxide (AAO) and at least one nano-porous track is formed in the nanotemplate. 
     
     
         20 . The method according to  claim 12 , further comprising separating the annealed alloy nanowires from the nanotemplate.