CALORIMETRIC AND MICROSTRUCTURAL STUDY OF NICKEL SILICON THIN-FILM REACTIONS

Thin-film reactions of nickel-silicon bilayers with an atomic concentration ratio of 2 Ni atoms to 1 Si atom are investigated by differential scanning calorimetry and plan-view transmission electron microscopy between 25 and 600-degrees-C. Several significant thermal effects can be seen on the thermograms: A small exothermal effect before the main peak is associated with grain growth of polycrystalline nickel. The activation energy (2.3 +/- 0.6 eV) is comparable to values obtained for grain growth processes in polycrystalline materials. The main exothermal peak is due to the formation of delta-Ni2Si. The activation energy (1.5 +/- 0.3 eV) is in agreement with literature results. A shoulder on the trailing edge of the main peak is interpreted by grain growth of the delta-Ni2Si phase. The complicated shape of the thermograms at higher temperatures is related to further grain growth processes of delta-Ni2Si.