The mechanism for the enhancement of Co Si2 thin film formation and film quality control by oxide-mediated cobalt silicidation with a Ti-capping layer is discussed. It is found that Ti absorbs oxygen from the Si Ox layer, which induces weak points in the Si Ox layer and then enhances Co diffusion as well as Co Si2 formation. The control of the reactions between Ti and Si Ox is significant because a low reaction rate cannot form a suitable thickness of Co Si2 film, whereas a high reaction rate tends to form the highly resistive CoSi phase. In addition, to maintain the Si Ox layer still existing after annealing is also important because if no Si Ox layer remains, unreacted Co would react with Si directly to form the highly resistive phase of CoSi, leading to the smooth interface between Co Si2 and Si and dense bulk Co Si2 thin film being destroyed.
|Number of pages||4|
|Journal||Journal of Vacuum Science and Technology B: Microelectronics and Nanometer Structures|
|State||Published - 1 Dec 2005|