Water assisted atomic layer deposition of yttrium oxide using tris( N , N '-diisopropyl-2-dimethylamido-guanidinato) yttrium(iii): process development, film characterization and functional properties.

We report a new atomic layer deposition (ALD) process for yttrium oxide (Y 2 O 3 ) thin films using tris( N , N' -diisopropyl-2-dimethylamido-guanidinato) yttrium(iii) [Y(DPDMG) 3 ] which possesses an optimal reactivity towards water that enabled the growth of high quality thin films. Saturative behavior of the precursor and a constant growth rate of 1.1 Å per cycle confirm the characteristic self-limiting ALD growth in a temperature range from 175 °C to 250 °C. The polycrystalline films in the cubic phase are uniform and smooth with a root mean squared (RMS) roughness of 0.55 nm, while the O/Y ratio of 2.0 reveal oxygen rich layers with low carbon contaminations of around 2 at%. Optical properties determined via UV/Vis measurements revealed the direct optical band gap of 5.56 eV. The valuable intrinsic properties such as a high dielectric constant make Y 2 O 3 a promising candidate in microelectronic applications. Thus the electrical characteristics of the ALD grown layers embedded in a metal insulator semiconductor (MIS) capacitor structure were determined which resulted in a dielectric permittivity of 11, low leakage current density (≈10 -7 A cm -2 at 2 MV cm -1 ) and high electrical breakdown fields (4.0-7.5 MV cm -1 ). These promising results demonstrate the potential of the new and simple Y 2 O 3 ALD process for gate oxide applications.