Nanolaminates of Zirconia and Silica Using Atomic Layer Deposition

In a low-pressure chemical vapor deposition reactor, alternating exposure of Si(100) substrates to tri(tert-butoxy) silanol and anhydrous zirconium nitrate deposited mixed films of zirconia and silica at 162 °C. The deposition rate, defined as the thickness (Å) per cycle, exhibited saturation behavior indicative of self-limiting growth. The maximum rate of approximately 12 Å/cycle exceeded the thickness expected for a single monolayer each of ZrO₂ and SiO₂. Metal composition of the films, as determined using Rutherford backscattering spectrometry, ranged from 3.3 to 49% zirconium. A singular reflection in the low-angle X-ray scattering pattern had a d spacing indicative of an ordered bilayer structure. The films were atomically smooth and their thickness was uniform across the entire substrate. Both the refractive indices, measured by ellipsometry, and the effective dielectric constants exhibited a linear dependence on the zirconium concentration.