Preparation and Properties of Pyrolytic Zirconium Dioxide Films

Abstract

Zirconium dioxide films in the thickness range of 500–8000Aring; have been prepared by chemical vapor deposition in the temperature range of 800°å 1000° C. The films were identified as fine‐grained (∼325Aå), nearly stoichiometric, monoclinic , using electron microprobe analysis, infrared absorption, and transmission electron microscopy. The films exhibited remarkable resistance to most aqueous acids and bases, although slight etching occurred in hot (220°C) phosphoric acid. The deposits had an index of refraction of and an optical energy gap of 5.12 eV. deposited on silicon offered little resistance to Na diffusion at 600°C, while films deposited on thermal were a good barrier due to pile‐up of the Na near the interface. The current density, , depended on the field, , where was 6 for the metal biased negatively and 2.75 or 5, depending on the magnitude of the field, for the opposite polarity. The dielectric constant in the frequency range of was relatively independent of frequency near 300° K and equal to approximately 18, however some dispersion was noted near 573°K. The a‐c conductivity could be represented by where is the measuring frequency and β a temperature dependent parameter, decreasing from . The dielectric strength of the films varied between , independently of thickness and polarity. High frequency (1 MHz) C‐V measurements indicated the presence of negative surface charge, which varied between . The structures exhibited instability under negative bias, indicative of negative charge being injected into the insulator. C‐V measurements on the double dielectric system showed that the presence of caused a flatband voltage displacement . In addition, the flatband voltage shifted as a function of time under negative bias and was found to obey the relationship .