The copper films with a thickness of 600 nm were prepared on TiN at 180 degrees C under O.5 Torr using chemical vapor deposition (CVD) method. The deposited films were subjected to be annealed at various temperatures (350-550 degrees C) in Ar and H-2(10%)/Ar ambients. The changes of the microstructures and the electrical resistivity after annealing were investigated. H-2(10%)/Ar was more effective than Ar as an ambient gas for the post annealing of the copper films, because smaller resistivity and larger grain size of the annealed film was given. The resistivity of the annealed film decreased, and the grain size increased with the annealing temperature. However, 550 degrees C is found to be inappropriate as the annealing temperature, because the out-diffusion of silicon through the TiN layer was observed. Upon annealing at 450 degrees C for 30 min in an H-2(10%)/Ar ambient, the grain size of the film increased from 148 nm to 219 nm, and the resistivity decreased from 2.35 mu Omega . cm to 2.12 mu Omega . cm.