Properties of High kappa Gate Dielectrics Gd sub 2 O sub 3 and Y sub 2 O sub 3 for Si

We present the materials growth and properties of both epitaxial and amorphous films of Gd sub 2 O sub 3 (epsilon=14) and Y sub 2 O sub 3 (epsilon=18) as the alternative gate dielectrics for Si. The oxide films were prepared by ultrahigh vacuum vapor deposition from an oxide source. The use of vicinal Si (100) substrates is key to the growth of (110) oriented, single domain films in the Mn sub 2 O sub 3 structure. Typical leakage current results are 10 sup (-5) A/cm sup 2 at 1V for an epitaxial Gd sub 2 O sub 3 film 34angstroms thick at an equivalent SiO sub 2 thickness of 15angstroms. The amorphous oxide films deposited in regular Si substrates showed a smooth morphology and interface with Si. A very low leakage of 10 sup (-6) A/cm sup 2 at 1V, and a specific capacitance as high as 35 fF/microns sup 2 were obtained for an amorphous Y sub 2 O sub 3 dielectric film 45angstroms thick, corresponding to an equivalent SiO sub 2 thickness of 10angstroms. The absence of SiO sub 2 segregation at the dielectric/Si interface is established from infrared absorption spectroscopy and scanning transmission electron microscopy. The amorphous Gd sub 2 O sub 3 and Y sub 2 O sub 3 films withstand the high temperature anneals to 850C, and remain electrically and chemically intact.