Tantalum nitride thin films with different thickness are sputtered deposited on silicon dioxide in the Cu/TaN/SiO2/Si multiplayer structure. Using resistivity analyses, X-ray diffraction, scanning electron microscopy and Rutherford backscattering spectroscopy, this work examines the impact of varying layer thickness on the crystal structure, resistivity, intermixing and reactions at the interfaces before and after annealing. The thinner the film thickness of TaN, the severe the reactions at the interface of Cu/TaN and consumed more conductive Cu. All the structures shown similar degradation process, and were found to be stable up to 500 degreesC for 35 min. Accelerated grain growth and agglomeration were also observed after annealing temperature higher than 550 degreesC at all Cu surfaces of the samples.