Characteristics of HfO2 thin films grown by plasma atomic layer deposition -: art. no. 053108

The characteristics of HfO2 films grown on Si substrates using a tetrakis-diethyl-amino-hafnium precursor by the remote plasma atomic layer deposition (RPALD) and direct plasma ALD (DPALD) methods were investigated by physical and electrical measurement techniques. The as-deposited HfO2 layer from RPALD exhibits an amorphous structure, while the HfO2 layer from DPALD exhibits a clearly visible polycrystalline structure. Medium energy ion scattering measurement results indicate that the interfacial layer consists of the interfacial SiO2-x and silicate layers. These results suggested that the stoichiometric change in the depth direction could be related to the energetic reactant in a state of plasma used in the plasma ALD process, resulting in damage to the Si surface and interactions between Hf and SiO2-x. The as-deposited HfO2 films using RPALD have the better interfacial layer characteristics than those using DPALD. A metal-oxide-semiconductor capacitor fabricated using the RPALD method exhibits electrical characteristics such as equivalent oxide thickness (EOT) of 1.8 nm with an effective fixed oxide charge density (Q(f,eff)) of similar to 4.2x10(11) q/cm(2) and that for DPALD has a EOT (2.0 nm), and Q(f,eff)(similar to-1.2x10(13) q/cm(2)). (c) 2005 American Institute of Physics.