Mechanical stress and stress evolution in interconnections may cause reliability problems in IC circuits. It is thus of great importance to understand the origin of this stress.
In this paper, the stress evolution during the solid state reaction between blanket titanium and aluminum films has been studied by in-situ substrate curvature measurements. Whereas the formation of TiAl3 is expected to induce large tensile stress because of a global volume decrease of 6-8%, curvature measurements of titanium/aluminum dual layers during annealing at 450°C suggests the formation of a compressive compound.
The evolution of the average force per unit width of the layer during the solid state reaction is interpreted on the basis of a phenomenological model used to describe stress evolution during silicide formation.