Bryan Danforth, Eric Dickey, Lotus Applied Technology, Hillsboro, Oregon
Single-component metal oxide films of alumina (Al₂O₃) and silica (SiO₂) grown by atomic layer deposition (ALD) have been well-characterized for their barrier properties. Neither SiO₂, nor Al₂O₃ exhibit robust barrier performance individually, but it has been previously shown that combining those binary oxide films to form ternary oxide (AlSiO) improves barrier performance, particularly in resilience to damp heat conditions. Previous methods for creating ternary metal oxides have been achieved by alternating layers to create nanolaminate structures, or by alternating ALD cycles between the two materials to create a homogeneous mixture. In this work, aluminum and silicon precursors are simultaneously co-delivered in a single vapor stream to grow a homogeneous mixture of AlSiO via a process that exhibits well-behaved, tunable composition control. It is shown that mixing these constituents within a specific compositional range results in optimal barrier performance, even in exposure to damp heat. This ALD process, featuring spatial precursor separation and plasma-enabled oxidation, provides a path to high-speed deposition at low substrate temperatures for growth of thin ultra-barrier coatings in batch, sheet-to-sheet, and roll-to-roll platforms.