Enhancement of TiSi2 Formation during Rapid Thermal Annealing in N 2 by the Presence of Native Oxide

Abstract

Ti/Si and systems are annealed by rapid thermal annealing (RTA) in ambient, and the formation of silicide and nitride is studied and compared. The sheet resistance of system is slightly higher than that of Ti/Si system because of native oxide (1.9 nm) at the Ti/Si interface. The only impurity detected by Auger electron spectroscopy at the Ti/Si interface is oxygen in the system, but no impurities are detected in the Ti/Si system. After RTA in ambient at 715°C for 10 s, it is interesting to find that the results of sheet resistance measurement for two systems are reversed. This suggests that the formation of Ti silicide in the system is easier than in the Ti/Si system whereas the formation of Ti nitride in the system is more difficult than in the Ti/Si system. X-ray measurement shows that the annealed systems have a higher intensity peak of and lower intensity peak of TiN as compared to those of the annealed Ti/Si systems. The AES study also supports the easier formation of in the system, where it is found that the diffusion of N from the ambient into Ti film is more difficult in the case of the system, such that the diffusion of Si toward the surface is easier. A difference is clearly observed in N and O diffusion through the TiN film and in the interface position. When the RTA time was varied from 10 s to 20 s and 30 s, X-ray diffraction shows the same results described above except that the to phase transformation occurs, and the resulting silicide phase is a mixture of C49 and By contrast, the TiN phase has no phase transformation but the intensity is more and more intense. The sheet resistance of the annealed system has lower values than those of the annealed Ti/Si system as the RTA increases. interface analysis is characterized by cross-sectional transmission electron microscopy. © 2001 The Electrochemical Society. All rights reserved.