Thermally stable yttrium–scandium oxide high-k dielectrics deposited by a solution process

Abstract

We investigated the thermal stability of electrical properties in ternary alloy (Y _x Sc_1−x )₂O₃ high-k oxides as a function of yttrium fraction, x. The yttrium–scandium oxide dielectric films are deposited using a facile ink-based process. The oxides have a stoichiometry-dependent relative dielectric constant of 26.0 to 7.7 at 100 kHz, low leakage current density of 10⁻⁸ A·cm⁻², high breakdown field of 4 MV⋅cm⁻¹, and interface trap density of 10¹² cm⁻²·eV⁻¹ with silicon. Compared with binary oxides, ternary alloys exhibit less frequency dispersion of the dielectric constant and a higher crystallization temperature. After crystallization is induced through a 900 °C anneal, ternary (Y_0.6Sc_0.4)₂O₃ films maintain their low leakage current and high breakdown field. In contrast, the electrical performance of the binary oxides significantly degrades following the same treatment. The solution-processed ternary oxide dielectrics demonstrated here may be used as high-k gate insulators in complementary metal-oxide semiconductor (CMOS) technologies, in novel electronic material systems and devices, and in printed, flexible thin film electronics, and as passivation layers for high power devices. These oxides may also be used as insulators in fabrication process flows that require a high thermal budget.