Influence of Cu diffusion conditions on the switching of Cu-SiO₂-based resistive memory devices

This paper presents a study of Cu diffusion at various temperatures in thin SiO₂ films and the influence of diffusion conditions on the switching of Programmable Metallization Cell (PMC) devices formed from such Cu-doped films. Film composition and diffusion products were analyzed using secondary ion mass spectroscopy, Rutherford backscattering spectrometry, X-ray diffraction and Raman spectroscopy methods. We found a strong dependence of the diffused Cu concentration, which varied between 0.8 at.% and 10^{- 3} at.%, on the annealing temperature. X-ray diffraction and Raman studies revealed that Cu does not react with the SiO₂ network and remains in elemental form after diffusion for the annealing conditions used. PMC resistive memory cells were fabricated with such Cu-diffused SiO₂ films and device performance, including the stability of the switching voltage, is discussed in the context of the material characteristics.