Electrical properties of ZrO2 gate dielectric on SiGe

Abstract

We report the electrical properties of a high dielectric constant (high-k) material, ${\mathrm{ZrO}}_{\mathrm{2}},$ deposited directly on SiGe, without the use of a Si buffer layer or a passivation barrier. ${\mathrm{ZrO}}_{\mathrm{2}}$ thin films of equivalent oxide thickness (EOT) down to 16.5 Å were deposited on strained SiGe layers by reactive sputtering. Results indicate that ${\mathrm{ZrO}}_{\mathrm{2}}$ films on SiGe have good interfacial properties and low leakage currents. Sintering in forming gas at $\text{350\hspace{0.05em}°}\mathrm{C}$ for 1 h could further improve the film quality. Although threshold voltage stability and dielectric dispersion become a concern for thick ${\mathrm{ZrO}}_{\mathrm{2}}$ films, thin ${\mathrm{ZrO}}_{\mathrm{2}}$ films of EOT less than 20 Å exhibit excellent electrical properties making them a good candidate for SiGe applications.