Characterization of the diffusium process in Al2O3 thin films based on ToF-SIMS measurements

In next generation charge trapping non-volatile memory devices the blocking oxide material (currently SiO2) has to be replaced by a highk dielectric thin film. The appropriate selection of a suitable material from a large variety of potential candidates requires precise analytical characterization techniques. This work focuses on Secondary Ion Mass Spectroscopy (SIMS) of Al2O3 thin films which were fabricated by atomic layer deposition on Si(001) wafers. These samples were treated by rapid thermal annealing in wide range of temperatures (750?1100\'0eC) and gas ambiences (N2, O2, H2). SIMS depth profiles indicate that Si diffuses from the substrate through the alumina during annealing which leads to a segregation of Si on the Al2O3 layer surface. Grain boundary diffusion was identified to have the most significant impact in the diffusion process. Furthermore the activation energy of the diffusion was found to be 0.6 eV/atom and 2.3 eV/atom for amorphous and crystalline samples, respectively. The influence of different Al2O3 sublayers (e.g. SiO2, Si3N4) and annealing conditions on the diffusion process will be discussed.