Silicidation process of Ti/TiNx/Si structures

Abstract

One of the most promising metallization schemes on silicon is the TiN/TiSi2/Si structure, since it takes advantage from both the good electrical contact between Si and TiSi2 and the property as a diffusion barrier of TiN. A related system that shows some interesting features is the Ti/TiNx/Si system. The results of two Ti/TiNx/Si structures with different nitride compositions (TiN0.7 and TiN0.8) have been studied. These structures show good electrical characteristics after thermal treatments (>900 °C) and allow one to obtain a smooth variation of the Schottky barrier height, which could lead to tunable contacts in the 0.57–0.53 eV range. Rutherford backscattering spectrometry and grazing incidence x-ray diffraction have been used to establish that the phase sequence observed during the silicidation process is very dependent on the diffusion rate of silicon through the TiNx layer. Finally, the slowest silicidation rate in the Ti/TiNx/Si system permits a higher incorporation of nitrogen from the atmosphere during the thermal treatment, as determined by nuclear reaction analysis. All these characteristics show that these structures can lead to the preparation of the TiN/TiSi2 C54/TiNx/Si in a single thermal treatment.