Self-aligned formation of epitaxial CoSi2, using a Co/Ti bilayer, on linear oxide (SiO2) patterned (100)Si substrates has been investigated. Rapid thermal annealing (RTA) at 550 degrees C resulted in lateral encroachment of silicide at the Si under the edge of the oxide. After RTA at 900 degrees C, even though an epitaxial CoSi2 layer was formed on the Si substrate, defects such as lateral encroachment and void were generated under the edge of the oxide. It was found that such defects yield device failures due to deterioration of the gate oxide and the shallow junction.