This work investigates the thermal interactions of Cu/Ta-N/Ta/fluorinated silicate glass (FSG) structures after annealing up to 900 degreesC, where Ta-N layers are as-deposited amorphous TaNx, (xsimilar to0.5) or polycrystalline TaN films. It is found that both TaN, and TaN barriers possess excellent capability to prevent Cu from diffusing after annealing at 700 degreesC or lower. After annealing at 800 degreesC, however, inward diffusion of Cu occurred in Cu/Ta-N/FSG structures. The outward diffusion of fluorine was also observed. After annealing at 900 C, reaction spots, which exposed the underlying FSG layer, were observed on the surface and formation of oxide phases was detected in the Cu/TaNx/FSG structure. However, exposure of FSG and oxidation were not found in the Cu/TaN/FSG structure. Nevertheless, in Cu/TaN/FSG structure. the sheet resistance was found to increase drastically after annealing at 900 degreesC. The significant increase in the sheet resistance could be attributed to the agglomeration of Cu. The influences of TaN, and TaN interlayers on the thermal stability of Cu/FSG system are discussed on the basis of chemical composition of these two Ta-N barriers. (C) 2004 Elsevier B.V. All rights reserved.