Bulk diffusion studies of metallizations on titanium- based contacts at 600°C

Abstract

The reactions occurring at the interface metal/Ti–Si–C, where metal=gold, aluminum or palladium and Ti–Si–C=Ti 3SiC 2, TiSi 2 or TiC, have been investigated on bulk diffusion couples. Prior to experimental work thermodynamic phase diagram calculations were performed to gain information about reactions likely to take place. After annealing cross sections of the metal/Ti–Si–C samples for 1.5 (metal+TiSi 2), 8 (metal+Ti 3SiC 2) and 23 h (metal+TiC) of samples were analyzed using SEM/EDX. The reactivity between the metals and the Ti–Si–C phases decreases in the sequence TiSi 2–Ti 3SiC 2–TiC and Au–Al–Pd. Using gold as metallization a liquid eutectic AuSi formed at the interface to TiSi 2 and Ti 3SiC 2, aluminum on both TiC and TiSi 2 results in formation of TiAl 3 and palladium on TiSi 2 reacts to an undetermined phase. In case a reaction occurred the layer thickness varied from over 100 μm for gold/TiSi 2 and 1.5 μm for palladium/TiSi 2.