Sputter deposition and characterization of TiB2/TiSi2 bilayer contact structure

Co-sputtering technique was applied to deposit amorphous titanium boride thin film, which has a promising barrier property against copper in microelectronic devices of high density integration level. The boron concentration in the Ti-B film is critical. Films with B/Ti ratio less than 2 were found to have poor barrier properties, but a boron rich titanium boride is a good barrier. It is preferential to have exact stoichiometry of TiB/sub 2/ since boron rich TIB/sub 2/ film is a very effective free boron source which might deteriorate the adjacent film structure. It is, therefore desirable to protect the semiconductor with an additional barrier against boron penetration. Titanium silicide was chosen as the barrier because diffusion of boron in TiSi/sub 2/ is negligible. Thus, the goal of this work is to form a TiB/sub 2//TiSi/sub 2/ bilayer barrier structure for ULSI semiconductor devices with copper metallization.