In situ transmission electron microscopy study of Ni silicide phases formed on (001) Si active lines

The formation of Ni silicides is studied by transmission electron microscop y during in situ heating experiments of 12 nm Ni layers on blanket silicon, or in patterned structures covered with a thin chemical oxide. It is shown that the first phase formed is the NiSi2 which grows epitaxially in pyrami dal crystals. The formation of NiSi occurs quite abruptly around 400 degree sC when a monosilicide layer covers the disilicide grains and the silicon i n between. The NiSi phase remains stable up to 800 degreesC, at which tempe rature the layer finally fully transforms to NiSi2. The monosilicide grains show different epitaxial relationships with the Si substrate. Ni2Si is nev er observed. (C) 2001 American Institute of Physics.