Improving electrical properties of pure nickel silicide by employing spike anneal as the second rapid thermal anneal

To create a nickel monosilicide (NiSi) film with superior electrical properties, two-step rapid thermal annealing (RTA) was optimized. Using in-situ chemical dry cleaning and increasing initial RTA temperature makes it possible to macroscopically transform nickel into NiSi without causing oxygen-contamination problems. Nevertheless, the Ni₂Si remaining on the top surface of the NiSi degrades its electrical properties. Accordingly, to microscopically enhance the integrity of the NiSi, the second RTA was also optimized. It was found that using a spike anneal for the second RTA completely transforms the residual Ni₂Si into NiSi, thereby improving the electrical properties of NiSi in 65-nm-node logic devices.