30–90 nm Ti films sputter deposited onto 50 nm Si3N4have been rapid thermal annealed for 30 s in Ar and N2ambients, and the phases formed identified using Auger electron spectroscopy, transmission electron microscopy, and electron diffraction. Reaction at 900 °C produces TiN surface and interfacial layers and an intermediate TiSi2layer. The Ti‐Si‐N ternary phase diagram is used to explain the reaction sequence.