Low-temperature atomic layer deposition of metastable MnTe films for phase change memory devices

초록

This work demonstrates an atomic layer deposition (ALD) process for achieving the MnTe film with metastable beta phase at a growth temperature of 100 degrees C. By employing a nitrogen-coordinated Mn precursor (bis[bis(trimethylsilyl)amido]manganese(ii)) and co-injecting NH3 with the Te precursor (bis(trimethylsilyl)telluride(ii)), stoichiometric and high-purity beta-MnTe films were deposited with self-limiting behavior on SiO2 substrate at a growth temperature of 100 degrees C. The metastable beta phase was stabilized without needing non-equilibrium synthesis methods, offering smooth (root-mean-squared roughness similar to 0.55 nm) nanocrystalline films with excellent uniformity and conformality on both planar and high-aspect-ratio structures. Substrate- and temperature-dependent growth behaviors revealed that the formation of beta-MnTe is governed by the chemical bonding environment, with the phase transitioning to the stable alpha phase on conductive substrates or at higher growth temperatures. Annealing studies demonstrated the beta to alpha phase transition via a displacive transformation, highlighting the feasibility of the ALD MnTe films for future phase change memory devices. This work offers insights into the ALD of metastable-phase chalcogenides, enabling their integration into advanced electronic devices.

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