| Microelectronics is a 300 G;We developed an experimental approach using x-ray diffraction to effectively characterize the entire reciprocal space. This experimental technique allows us to identify, using a single measurement, the texture, and nature of all phases in a sample, deformations of the lattice, signals from the thermal diffuse scattering resulting from the interaction of the x-rays with the phonons of the substrate and the presence of planar defects. This technique allowed us to demonstrate that the texture of the phases forming has a crucial impact on the reaction between Ni and Si or is the marker of phenomenon important to understand the reaction. Software, developed to process the raw data and analyze the three dimensional reciprocal space, were made available to the scientific community.;First, we characterize the reaction of 10 nm Ni on Si(001). During the reaction, the first phases to form are Ni2Si and an epitaxial phase at the interface. The Ni2Si phase is consumed by the metastable theta phase. We explain its formation by a nucleation facilitated by the inheritance of the Ni2Si fiber texture. Following the decomposition of the theta phase, which occurs when the temperature allowing the nucleation of the NiSi phase is reached, we observe the regrowth of Ni2Si. This decomposition occurs because a mixture Ni2Si and NiSi has a lower free energy than the theta phase. The NiSi partially inherits the texture of the theta phase.;The reaction between Ni and Si (1 11) is drastically different than the reaction occurring on Si(001). While the phases present in the reaction on Si(001) exhibit mainly fiber textures, the phases present on Si(111) exhibit mainly epitaxial texture. After the deposition, a small proportion of epitaxial theta phase is observed. During anneals, this phase is quickly consumed by the Ni 2Si that inherits the same texture as the epitaxial theta phase. At higher temperature the theta phase does not consume Ni2Si, as observed on Si(001). We can identify different factors that could explain this difference: (i) the interface is more abrupt because of the epitaxial interface and the volume with a proper concentration to nucleate theta is too small, (ii) the concentration in the Ni2Si at the interface is richer in Ni for kinetic reasons and there is therefore no thermodynamical drive to form theta, (iii) the interfacial layer between the Ni2Si and the Si(111) is of different nature than on Si(001) and is more stable in equilibrium with Ni2Si than the theta phase.;On Si(111), Ni2Si is consumed by Ni3Si2 instead of the theta phase. The nucleation of Ni3Si2 on Si(111) is explained by the presence of the Ni2Si/Si interface at a higher temperature on Si(111), which ensures the presence of enough energy to cross the nucleation barrier of Ni3Si2. The NiSi then forms at higher temperatures.;Overall, we have demonstrated that nucleation is key to the phase selection during the thin film reaction. On Si (001), the theta phase nucleation is facilitated by a texture inheritance, while on Si(111) the nature of the interface favors the nucleation of Ni3Si2. The simultaneous growth of two phases, Ni2Si and NiSi, is explained by the decomposition of a metastable phase and will occur as soon as NiSi can nucleate. As nucleation is key to this reaction, any factor affecting it (concentrations, nature and size of the interface) will imply a variation to process conditions use to form contacts on transistors. |
