TiN/TiSi₂ Formation Using TiN_x Layer and Its Feasibilities in ULSI

A new technique for the formation of the TiN/TiSi₂ bilayer using a TiN_x layer was described. The TiN_x layer was deposited by sputtering in a mixed gas atmosphere of argon and nitrogen, wherein the concentration of nitrogen was controlled to be lower than that required in the formation of stoichiometric TiN. The nitrogen atoms in the Ti matrix relaxed the mechanical stress of the deposited film and also limited the number of Ti atoms available for the interaction with the Si substrate (i.e., silicidation reaction). Upon thermal annealing, TiN_x changed to the bilayer structure of TiN/TiSi₂, in which the thickness of the overlying TiN was so great that only a rather thin TiSi₂ was formed between TiN and the Si substrate. Moreover, TiN had the (111) texture, and TiSi₂ formed on the (100)Si substrate was found to show well-aligned epitaxial properties with an extremely uniform thickness.