Semiconductor devices and methods for fabricating the same. The devices include a substrate, a catalyst layer, a second dielectric layer, and carbon nanotubes (CNTs). The substrate comprises an overlying first dielectric layer with an electrode embedded therein. The catalyst layer overlies the electrode and the first dielectric layer and substantially comprises Co and M.sub.1, wherein M.sub.1 is selected from a group consisting of W, P, B, Bi, Ni, and a combination thereof. The second dielectric layer overlies the catalyst layer and comprises an opening exposing parts of the catalyst layer. The carbon nanotubes (CNTs) are disposed on the exposed catalyst layer and electrically connect the electrode.