The effects on metal transport and loss in Hf and La aluminate films deposited on Si induced by rapid thermal annealing at 1000°C were investigated. Decomposition of HfAlO films on Si during rapid thermal annealing was reveled by the decrease of the Hf and Al contents. Metal loss from LaAlO/Si structures was also observed following annealing in vacuum, while strong metal transport and interfacial reaction were induced by annealing in a O2 containing atmosphere. These instabilities were hampered by means of post deposition thermal nitridation in NH3 at temperatures lower than 1000°C performed before the rapid thermal annealing step. The role of nitridation is discussed in terms of the N profiles in the nitrided structures.