Preparation of AIN Coatings on Mo by RF‐Reactive Ion Plating: The Deposition Mechanism

Abstract

Aluminum nitride films were deposited at 0.15–0.33 μm/min on Mo by rf‐reactive ion plating as an application of a low‐Z material or a refractory coating. The structure, chemical state, and composition of the deposits were analyzed by scanning electron microscopy, x‐ray diffraction, infrared and AES spectra, and x‐ray microanalyzer; the deposits were confirmed to be aluminum nitride. Any nitride films improved the oxidation resistance of Mo up to 1100°–1200°C, and the adhesion and thermal cycle stability of the coatings were good. The composition of the deposit effectively depended on the partial pressures of reactant gases. The free Al of the nonstoichiometric deposits may lead to local film failure under high temperature vacuum. The relation between degree of nitridation and mean free path of the gas suggests that the reaction between Al and occurs on the substrate surface. The morphology is discussed in terms of the mean free path, and the nitridation rate is also described.