MECHANISMS OF EPITAXIAL COSI2 FORMATION IN THE MULTILAYER CO/TI-SI(100) SYSTEM

We describe how the unique growth environment provided by a multilayer Co/Ti(O)-Si structure leads to the formation of epitaxial CoSi2/Si(100). A key factor is the preferential nucleation of (311) CoSi which is the dominant phase from 650 to 800-degrees-C in this multilayer system. Epitaxial CoSi2 then nucleates at the (311) CoSi/(100) Si interface and grows during a 900-degrees-C second annealing. Having Ti as the first layer in contact with the Si substrate reduces the native Si oxide and residual impurities. The amorphous Ti(O) provides a uniform supply of slowly diffusing Co that promotes preferential CoSi formation. The upper Co and Ti layers serve to stabilize the reaction and suppress agglomeration.