Ju-Chul Park

Epitaxial C49–TiSi2 phase formation on the silicon (100)

The crystallographic characteristics of an epitaxial C49–TiSi2 island formed on the Si (100) substrate were investigated by high-resolution transmission electron microscopy (HRTEM). The analysis results clearly showed that the optimum epitaxial relationship between the C49–TiSi2 phase and the Si substrate is [001]C49//[011]Si and (010)C49//(100)Si. We found that the interfacial energy at the C49–TiSi2/Si interface is relaxed by the formation of misfit dislocations and/or atomic steps, and consequently the epitaxial C49 phase is thermally stable so it is not transformed to the C54 phase even after high-temperature annealing above 900 °C. Further, the mechanism on the formation of the epitaxial C49 phase on the Si substrate and the atomic arrangement of stacking faults lying on the C49 (020) plane are discussed through the analysis of HRTEM images.

Fabrication and Characterization of Ru Thin Films Prepared by Liquid Delivery Metal-Organic Chemical Vapor Deposition

Ruthenium thin film was obtained by the liquid delivery metal organic chemical vapor deposition method using a new Ru(C8H13O2)3 precursor for the advanced capacitor electrode in Gbit-scale dynamic random access memory. Deposition was done on a TiN barrier layer in the range of 250–400°C. The thin film characterization was performed in terms of the resistivity, change of crystal structure, surface morphology, microstructure and film purity. The resistivity depended on the impurity, grain shape and crystalline structure of the film. The minimum resistivity of 13.9 µΩcm was obtained at 400°C. The X-ray diffraction and X-ray photoelectron spectroscopy results indicate that the RuO2 phase and the silicidation are not observed and are independent of the deposition temperature. The carbon and hydrogen contaminants in the Ru film were shown to disturb the crystal preferred orientation growth. The Ru film was found to grow perpendicular to the substrate and to be the columnar structure.

Nanoscale analysis on interfacial reactions in Al–Si–Cu alloys and Ti underlayer films

Solid-phase reactions at the interface between sputtered Al–Si–Cu alloys and Ti films were investigated at the atomic scale by high-resolution transmission electron microscopy and energy dispersive x-ray spectroscopy (EDS) coupled with a field-emission (scanning) transmission electron microscope. The analysis results showed that the interface is composed of an amorphous-like Ti–Si layer, an intermediate-crystalline layer, and a Si-dissolved TiAl3 layer containing dissolved Si TiAl3 with a crystallographic relationship with the Al film. The nanometer-scaled interlayers effectively play a role as a barrier suppressing the interdiffusion reaction of Al and Ti during annealing treatment. Further, the quantitative composition of the interlayers was revealed by the analysis of the intensity profiles obtained from EDS elemental maps.

Characterization on microstructures of tungsten/barrier metals (TiN,WNx)/silicon multilayer films

Microstructures of W/barrier metals (TiN,WNx)/Si multilayer films followed by heat treatment were precisely investigated by x-ray diffraction and high-resolution transmission electron microscopy. The analysis results showed that in the W/TiN/Si stacked film having the W (110) and (200) preferred orientations, the TiN film itself plays a role as a barrier for the reaction of W and Si, whereas in the case of the WNx barrier having the W (110) one, the amorphous SixNy layer with a thickness of a few nanometers works effectively as a barrier, which was formed during the deposition and denudation process of the WNx film. Furthermore, the nanometer-scaled interfacial reaction in the multilayer films was clearly investigated by x-ray photoelectron spectroscopy coupled with chemical etching and an energy-filtered elemental mapping technique. Based on the results, effects of barrier metals on the W preferred orientation and the interfacial reaction were crystallographically and thermodynamically discussed.

Preparation and characterization of RuOx thin films by liquid delivery metalorganic chemical vapor deposition

RuOx films were deposited by liquid delivery metalorganic chemical vapor deposition method using a new Ru(C8H13O2)3 precursor for the advanced capacitor electrode in Gbit-scale dynamic random access memory. Deposition was carried out on a TiN barrier layer in the range of 250–400°C and the ratio of the O2 flow rate to the total flow rate of Ar and O2 was varied from 20 to 80%. RuOx thin films were annealed at 650°C for 1 min with Ar, N2 or NH3 ambient. Film characterization was performed in terms of resistivity, crystal structure, surface morphology, microstructure and film purity. The resistivity depended on the impurity, grain density and crystalline structure of the film. The oxygen used to form Ru the oxide was found to eliminate the carbon and hydrogen elements in an organic source. The O2 flow ratio that changes the crystal structure of the films from Ru to RuO2 was found to be 40%. The metallic Ru phase forming a RuO2/Ru bilayer at the RuO2/TiN interface was observed at O2 flow ratios of 50% and 60%. The X-ray diffraction results indicate that the RuO2 phase and the silicidation are not observed regardless of the ambient gases. Ar was more effective than N2 and NH3 as an ambient gas for the postannealing of the Ru films.

Crystallographic Characterization of the (Bi, La) 4 Ti 3 O 12 Film by High-Resolution Electron Microscopy

The crystallographic characteristics of the thin film, which is considered as an applicable dielectrics in the ferroelectric RAM device due to a low crystallization temperature and a good fatigue property, were investigated at the atomic scale by high resolution transmission electron microscopy and the high resolution Z-contrast technique. The analysis showed that a (00c) preferred orientation and a crystallization of the film were enhanced with the diffraction intensity increase of the (006) and (008) plane as the annealing temperature increased. It indicated a change of the atomic arrangement in the (00c) plane. Stacking faults on the (00c) plane were also observed. Through the comparison of the high-resolution Z-contrast image and the atomic model, it was evaluated that the intensity of the Bi atom was different according to the atomic plane, and it was attributed to a substitution of La atom for Bi at the specific atom position.

Crystallographic and Interfacial Characterization of Al 2 O 3 and ZrO 2 Dielectric Films Prepared by Atomic Layer Chemical Vapor Deposition on the Si Substrate

Crystallographic characteristics and interfacial structures of and dielectric films prepared by atomic layer chemical vapor deposition (ALCVD) were investigated at atomic scale by high-resolution transmission electron microscopy (HRTEM) and energy dispersive X-ray spectroscopy (EDS)/electron energy-loss spectroscopy (EELS) coupled with a field-emission transmission electron microscope. The results obtained from cross-sectional and plan-view specimens showed that the film was crystallized by annealing at a high temperature and its crystal system might be evaluated as either cubic or tetragonal phase. Whereas the film crystallized during deposition at a low temperature of ∼ was composed of both tetragonal and monoclinic phase. The interfacial thickness in both films was increased with the increased annealing temperature. Further, the interfacial structures of Xand films were discussed through analyses of EDS elemental maps and EELS spectra obtained from the annealed films, respectively.