High Temperature Process Limitation on TiSi₂

Since is perhaps the most attractive candidate for the self‐aligned silicide technology, it is important to understand the high temperature process limitations of this material. Thin films are formed on single‐crystal silicon, or polysilicon, and, when annealed in He or at temperatures of 900°C or higher, result in degradation of surface morphology and a drastic increase in sheet resistance. Eventually, isolated agglomerates are formed on the surface in case of He annealing. In the case of nitrogen annealing, they are covered with . Shallow junctions with a thin self‐aligned layer formed on top were electrically stable up to 900°C. Heat‐treatment beyond this temperature caused both the junction leakage and the contact resistance to increase. In addition to agglomeration, when thin films were formed on polysilicon, mixing of into polysilicon at temperatures beyond 850°C was observed. In the case of MOS devices, this degrades gate integrity.