“…Thus, recently, the Cu conduction lines produced with a high density of the twin boundaries have attracted great attention due to its unique properties in the conductivity and electro-migration resistance [ 12 , 13 , 14 ]. Twin boundaries in the Cu phase can be produced by either mechanical or annealing treatment, which are called mechanical twin and annealing twins, respectively [ 15 , 16 , 17 , 18 , 19 , 20 ]. Furthermore, many researchers reported that twin boundaries can be produced by means of the electroplating [ 9 , 12 , 21 , 22 , 23 ].…”