Robustness of ultrathin aluminum oxide dielectrics on Si(001)

The stability of Al2O3 films during thermal processing will help determine their usefulness as an alternative gate dielectric for advanced complementa ry metal-oxide-semiconductor devices. We used medium energy ion scattering and atomic force microscopy to examine the degradation of ultrathin Al2O3 l ayers under ultrahigh vacuum annealing and the effects of low-temperature o xidation. No degradation is observed at 900 degreesC, but voids appear at h igher temperatures. Growth of interfacial SiO2 takes place during low-press ure oxidation at 600 degreesC, which may limit the capacitance of extremely thin structures. (C) 2001 American Institute of Physics.