Atomic Layer Deposition of Lu Silicate Films Using [(Me[sub 3]Si)[sub 2]N][sub 3]Lu

Abstract

Rare-earth silicates are promising materials for future microelectronic devices based on high dielectric constant dielectrics. In this work, we report the investigation of Lu silicate films deposited using atomic layer deposition on Si(100). The films were grown from tris[bis(trimethylsilyl)amido]lutetium— [(Me3Si)2N]3Lu[(Me3Si)2N]3Lu (where Me=CH3Me=CH3 ), which can supply both Lu and Si. Water or ozone were used as oxygen sources. The films deposited using the latter are shown to be richer in Si. The films are amorphous as grown, have a low physical roughness, an electronic density lower than expected for both crystalline and amorphous stoichiometric Lu silicates, and promote a SiO2SiO2 -rich interfacial layer on Si(100). Crystallization, observed only in films deposited using O3O3 , has an onset temperature above 900°C900°C . Annealing at 950°C950°C induces film densification. Signs of crystallization are observed only in the electron diffraction patterns of the annealed film deposited using O3O3 as oxygen source, but the resulting crystallographic phases cannot be unequivocally identified. The κ values of the dielectric stacks are between 5 and 7. The conduction band offset between the Lu silicate layer and Si(100) measured for the film deposited using O3O3 is 2.2eV2.2eV .