Film modification by low energy ion bombardment during deposition

Heteroepitaxial Y2O3 films were grown on Si(100) substrates by the technique of reactive ionized cluster beam deposition. The crystallinity of the films was investigated with reflection high energy electron diffraction (RHEED), glancing angle x-ray diffraction (GXRD), and the interface was examined by high resolution transmission electron microscopy (HRTEM). Under the condition of 5 kV acceleration voltage at the substrate temperature of 800 °C, the Y2O3 film grows epitaxially on the Si(100) substrate. RHEED and GXRD results revealed that the epitaxial relationship between Y2O3 and Si(100) is Y2O3(110)//Si(100), and HRTEM observation showed a sharp interface without an amorphous layer.

Epitaxial growth of Y2O3 films on Si(100) without an interfacial oxide layer

Magnetron plasma processes involving metal atoms and clusters are reviewed. The formation of metal atoms near the cathode and their nucleation in a buffer gas flow are discussed. The flow of a buffer gas with metal clusters through a magnetron chamber disturbs the equilibrium between the buffer gas flow and clusters near the exit orifice and is accompanied by cluster attachment to the chamber walls. Cluster charging far off the cathode, the disturbance of equilibrium between the buffer gas flow and cluster drift, and the attachment of charged clusters to the chamber walls — the factors determining the output parameters of the cluster beam escaping the magnetron chamber — are analyzed. Cluster deposition on a solid surface and on dusty plasma particles is considered.

https://iopscience.iop.org/article/10.1070/PU2007v050n05ABEH006138/pdf

Magnetron plasma and nanotechnology

Deposition of titanium/titanium oxide clusters produced by magnetron sputtering

The processes are considered in a cluster plasma consisting of a dense plasma of a buffer gas and a metal admixture These processes involving clusters in a gas or plasma include nucleation processes in a supersaturated vapor, formation of metallic clusters in a dense gas from metal-containing compounds, and chemical processes in the course of this conversion, processes of cluster charging in a plasma and under the action of an electron beam The basic methods are analyzed for cluster generation including formation and growth of clusters in free jet expansion of a gas, under laser action on the metallic surface, and growth of clusters in a plasma resulted from injection of metal-containing molecules into a plasma Some applications of cluster beams are discussed, which include fabrication of thin films, new materials, and creation of a hot nonuniform plasma

Generation of cluster beams

The ionized cluster beam (ICB) deposition and epitaxial process is an ion-assisted technique by which high quality films of metals, dielectrics and active semiconductor materials can be formed at a low substrate temperature in a technical-grade vacuum system. In the ICB process, film material is vaporized from a confinement crucible under conditions which result in the formation of aggregate clusters of atoms held together by weak forces. Clusters can be ionized by electron impact and subsequently accelerated by high potentials. Through selection of available parameters, it is possible to control the average energy of depositing species over the range from thermal ejection to above 100 eV per atom. It is within this range that optimum conditions for film growth are generally achieved. In the ICB deposition, characteristics of the deposition are mainly caused by both the structural characteristic of the clusters and the effects of ionization and acceleration of the clusters.

Toshinori Takagi

Papers

Ionized-cluster beam deposition and epitaxy