Synthesis of ZrO2 and Y2O3‐Doped ZrO2 Thin Films Using Self‐Assembled Monolayers

Abstract

Undoped or Y2O3‐doped ZrO2 thin films were deposited on self‐assembled monolayers (SAMs) with either sulfonate or methyl terminal functionalities on single‐crystal silicon substrates. The undoped films were formed by enhanced hydrolysis of zirconium sulfate (Zr(SO4)·4H4O) solutions in the presence of HCl at 70°C. Typically, these films were a mixture of two phases: nanocrystalline tetragonal‐ (t‐) ZrO2 and an amorphous basic zirconium sulfate. However, films with little or no amorphous material could be produced. The mechanism of film formation and the growth kinetics have been explained through a coagulation model involving homogeneous nucleation, particle adhesion, and aggregation onto the substrate. Annealing of these films at 500°C led to complete crystallization to t‐ZrO2. Amorphous Y2O3‐containing ZrO2 films were prepared from a precursor solution containing zirconium sulfate, yttrium sulfate (Y2(SO4)38·H2O), and urea (NH2CONH2) at pH 2.2–3.0 at 80°C. These films also were fully crystalline after annealing at 500°C.