Atomic layer deposition of YO films using a novel liquid homoleptic yttrium precursor tris(-butylcyclopentadienyl)yttrium [Y(BuCp)] and water

Atomic layer deposition (ALD) of Y 2 O 3 thin films was studied using a novel homoleptic yttrium ALD precursor: tris( sec -butylcyclopentadienyl)yttrium [Y( s BuCp) 3 ]. Y( s BuCp) 3 is a liquid at room temperature. The thermogravimetry curve for Y( s BuCp) 3 is clean, with no indication of decomposition or residue formation. Thermogravimetry-differential thermal analysis measurements showed that Y( s BuCp) 3 is stable for 18 weeks at 190 °C. Y( s BuCp) 3 has a homoleptic structure. Thus, a reduction in manufacturing costs is expected compared to those associated with heteroleptic precursors because additional chemical synthesis steps are usually necessary to produce heteroleptic compounds. In addition, ALD of Y 2 O 3 was demonstrated using Y( s BuCp) 3 and water as a co-reactant. The deposition temperature was varied from 200 to 350 °C. The growth rate was 1.7 Å per cycle. In addition, neither carbon nor nitrogen contamination was detected in the Y 2 O 3 films by X-ray photoelectron spectroscopy. Furthermore, smooth films were confirmed by X-ray secondary-electron microscopy. The root-mean-square roughness was measured to be 0.660 nm by atomic force microscopy. Metal-insulator-semiconductor (MIS) Pt/Y 2 O 3 /p-Si devices were fabricated to evaluate the electrical properties of the Y 2 O 3 films. An electric breakdown field of −6.5 MV cm −1 and a leakage current density of ∼3.2 × 10 −3 A cm −2 at 1 MV cm −1 were determined. The permittivity of Y 2 O 3 was estimated to be 11.5 at 100 kHz. Therefore, compared with conventional solid precursors, Y( s BuCp) 3 is suitable for use in ALD manufacturing processes. Atomic layer deposition of Y 2 O 3 films was demonstrated using a novel liquid homoleptic yttrium precursor Y( s BuCp) 3 and water. The deposited Y 2 O 3 films exhibit high purity, high crystallinity, a smooth surface, and high electronic performance.