Characteristics of Amorphous Bi2Ti2O7 Thin Films Grown by Atomic Layer Deposition for Memory Capacitor Applications

Abstract

films were deposited on sputtered substrates by atomic layer deposition using tris(1-methoxy-2-methyl-2-propoxy)bismuth , titanium tetraisopropoxide as Bi and Ti precursors, and as oxidant, respectively. The wafer temperature was varied from 225 to 300°C. The growth rates decreased from at 225°C to at 300°C. The Bi concentration in the film decreased with increasing growth temperature and it could be controlled within a certain range by changing the Bi feeding at a given temperature. The as-grown films were amorphous but contained metallic Bi at high growth temperatures and high Bi concentrations. Bi and Ti piled-up on the film surface and the Ru interface, respectively. The electrical leakage property of the thin film became worse with increasing deposition temperature and Bi concentration due to the metallic Bi formation. The dielectric constant at the optimum deposition condition (225°C) was , and the leakage current level was at at a film thickness of . Reasonable conformal film thickness and cation composition over contact holes with a diameter of and a depth of were obtained.