We investigated the mechanism of cracking between the inter/intra-metallic dielectric (IMD) silicon oxide films after anneal process. The cracks were initiated at the top corner of aluminum lines, then propagated through the silicon oxide films. Thus, the extrusion of melted Al along the IMD cracks, caused metal line bridge. These cracking conditions involve the stresses of the IMD films as well as their thickness. Namely, the cracking was suppressed not only by decreasing the magnitude of compressive stress but also increasing the film thickness on silicon oxide films. These results are in accordance with the finite element method stress analysis using silicon oxide film stress and thickness. In this paper, we focused on the analysis of crack formation mechanism on the IMD film, and finally proposed an empirical criterion for crack-safety condition. (C) 2011 Elsevier B.V. All rights reserved.