Rapid thermal annealing (RTA) of Cr films in an NH3 ambient was found to be effective in improving the barrier capability of Cr films in a Cu metallization system. The Cu/Cr/p(+)n junction diodes whose Cr barrier was RTA treated at a temperature of 400 degrees C were able to sustain a 30 min thermal annealing at temperatures up to 700 degrees C without causing degradation to the electrical characteristics of the diodes. This is a 200 degrees C improvement over the junction diodes using a Cr barrier without RTA treatment. Nitrogen degradation in the grain boundaries of the Cr layer was presumably responsible for the improvement in the barrier capability. How ever, the efficiency of improvement in the barrier capability was reduced for RTA treatment at temperatures above 600 degrees C. With RTA treatment at 800 degrees C, the material analysis indicated that SiO2 was formed in addition to oxygen segregation at the Cr/Si interface. The SiO2 thus formed resulted in a poor Cr/Si interface that caused larger leakage currents far the Cu/Cr/p(+)n junction diodes under reverse bias. Moreover, outward diffusion of Si was found in the 800 degrees C RTA-treated Cr layer, which facilitated formation of Cu3Si within the Cr layer for the 800 degrees C annealed Cu/Cr/Si samples. In summary, the improvement in the barrier capability of the Cr layers is closely related to the RTA temperature, and the optimum temperatures were determined to be between 400 and 600 degrees C.