Development of a flux-film-coated sputtering (FFC-sputtering) method for fabricating c-axis oriented AlN film

In this study, we developed a novel growth method named “Flux-Film-Coated (FFC) sputtering.” In this method, nitrogen radicals were supplied to the Al–Sn flux at around 600 °C followed by the deposition of an Al–Sn metal film on a sapphire substrate as flux, which resulted in the growth of high-quality AlN films. The nitrogen radical, which is the source of nitrogen for the growth of AlN, was generated by the radio frequency plasma in a nitrogen atmosphere. Using a zirconia target in the plasma generation process, nitrogen radicals were easily generated because the zirconia was not etched in a pure nitrogen atmosphere, which enabled us to fabricate the AlN film using the flux method in the sputtering chamber in a single step. The crystallinity of the synthesized AlN determined using the FFC-sputtering method was remarkably improved when compared with that of the AlN film deposited using the reactive sputtering method.