substrate 100 referring again to example fig1 a cover film 108 may be formed over the inside surface of the trench t as shown in fig4 a barrier layer 110 is formed over the cover film 108 the cover film 108 may be formed of sin and the barrier layer 110 may be formed of tan ta wn ti tin tisin tasin or the like the barrier layer 110 may be formed in multiple layers with combinations of these or equivalent materials among other effects the barrier layer 110 prevents material in a metal layer from being diffused into another layer the barrier layer may also enhance the adhesion between the insulating film and the metal layer a metal line 112 is formed so as to fill the trench defined by the barrier layer 110 wherein the metal line 112 is electrically connected with the lower conductor the metal line 112 is formed of a conductive low resistance material such as copper below a method for forming the metal line of the semiconductor device having the above configuration will be explained with reference to example fig2 to 4 together with fig1 example fig2 to 4 provide cross sectional views to describe the manufacturing method of the metal line of the semiconductor device in accordance with embodiments as shown in fig2 the etch stop layer 104 and the interlayer insulating film 106 are deposited over the substrate 100 having the lower conductor 102 then a trench.