A thermally stable Cu/ZrN/Si contact system using a ZrN diffusion barrier of low resistivity was developed. In the contact system, the growth of an oriented ZrN(100) layer on Si(100), and subsequent growth of a Cu(110) layer on ZrN(100) were observed. The obtained contact system was fairly stable after annealing even at 750 degrees C for 1 h without any diffusion and/or reactions at either the interface of Cu/ZrN or ZrN/Si. It was revealed that the ZrN layer with low electrical resistivity showed a high performance as a diffusion barrier, and was one of the excellent materials for the use in ultralarge scale integration technology.