Robustness of ultrathin aluminum oxide dielectrics on Si(001)

Abstract

The stability of Al2O3 films during thermal processing will help determine their usefulness as an alternative gate dielectric for advanced complementary metal-oxide-semiconductor devices. We used medium energy ion scattering and atomic force microscopy to examine the degradation of ultrathin Al2O3 layers under ultrahigh vacuum annealing and the effects of low-temperature oxidation. No degradation is observed at 900 °C, but voids appear at higher temperatures. Growth of interfacial SiO2 takes place during low-pressure oxidation at 600 °C, which may limit the capacitance of extremely thin structures.