disilicide

Disilicide is a binary compound formed between silicon and another element in which silicon is present in a 2:1 ratio, giving the general formula MSi2. The term is commonly used for metal silicides with this stoichiometry, including transition metals and rare-earth metals. These compounds occur across a range of metals and form intermetallic phases with silicon.

Crystal structures of disilicides vary with the metal and can include tetragonal, orthorhombic, or fluorite-related lattices. The silicon atoms often participate in Si–Si bonding within the crystal, while metal atoms occupy surrounding positions. The structure influences properties such as electrical conductivity, thermal stability, and diffusion behavior.

Synthesis of disilicides typically involves direct combination of silicon with the metal at elevated temperatures, or deposition of the elements followed by annealing. In thin films, chemical vapor deposition or sputtering is commonly used, especially for forming silicides at silicon interfaces in microelectronic devices.

Properties of disilicides are diverse. They generally exhibit high melting points and good thermal stability. Their electrical behavior ranges from metallic to semiconducting depending on the specific metal and crystal structure. Some disilicides act as diffusion barriers or provide stable, low-resistivity contacts in silicon-based technologies.

Applications of disilicides are prominent in integrated circuits, where silicidation forms metal silicides at silicon interfaces to create reliable, low-resistance contacts. Prominent examples include titanium disilicide (TiSi2) and cobalt disilicide (CoSi2), which have been widely employed in silicon device fabrication.

See also: silicide, metal silicide, intermetallic compound.