$N^+$ beam modified diffusion barriers have been proposed for Cu metallization . The crystalline phases of W and Ti thin films change from polycrytalline to amorphous phase by the N ion implantation of 1~$3 imes 10^{17}$atoms/$ extrm{cm}^2$. The comparison between these amorphized diffusion barriers and the conventional W and TiN films shows that the amorphized W and Ti diffusion barriers are superior to the conventional w and TiN for protecting the Cu diffusion barriers are superior to the conventional W and TiN for protecting the Cu diffusion at the annealing temperature range $600^{circ}C$~$800^{circ}C$ for 30min. This is a worldwidely new and excellent result on the high temperature thermal stability of diffusion barrier.