Formation of a stratified lanthanum silicate dielectric by reaction with Si(001)

We have characterized the structure and electrical properties of lanthanum silicate layers formed on Si(001) by reaction of lanthanum oxide with the substrate. Postoxidation of the deposited films results in the formation of a stacked dielectric with a lanthanum silicate layer atop an interfacial layer of ${\mathrm{SiO}}_{\mathrm{2}}.$ This structure combines the interfacial properties of ${\mathrm{SiO}}_{\mathrm{2}}$ with the large permittivity of lanthanum silicate. Although the resulting film has leakage properties far superior to an equivalent thickness of ${\mathrm{SiO}}_{\mathrm{2}},$ there is evidence of significant quantities of ionic charge that must be eliminated before use in electronic applications.