Aqueous solution–gel preparation of ultrathin ZrO2 films for gate dielectric application

Zirconia ultrathin films were deposited by aqueous chemical solution deposition, using citratoperoxo-Zr(IV) precursors with different citric acid content. The precursor synthesis, thermal decomposition and crystallization of oxide powders were studied. This showed an effect of the citric acid content in every stage. The precursors were applied for the deposition of uniform, ultrathin films (< 30 nm thickness) as well. Tetragonal ZrO2 crystallized starting from 500 °C for thin films with a thickness of 10 nm. This was independent of the citric acid content in the precursor. The topography after annealing at 600 °C was also similar. However, annealing at higher temperatures led to coarser grain size. The dielectric constant was high (~ 21–22) and comparable to ZrO2 deposited by atomic layer deposition.