Do-Heyoung Kim

Epitaxial growth of CoSi2 layer on (100)Si and facet formation at the CoSi2/Si interface

The epitaxial nature of the CoSi2 formed on the (100)Si substrate as a result of annealing a Co/Ta bilayer at 500–1000 °C for 20 s in N2 atmosphere is described. At the early stage of annealing, diffusion of Co and Si occurs across the interlayed Ta layer, first forming a CoSi layer on the Si substrate. After that, CoSi2 grains nucleate at the CoSi/Si interface and grow laterally parallel to the surface. Due to a difference in mobility the CoSi2 grains at the interface of the CoSi/Si impede the interface movement, leading the facet formation. Even after annealing below 600 °C, the epitaxial CoSi2 grains are nucleated at the limited area of the nonepitaxial CoSi/Si interface and the faceted corner, and grow laterally along the Si surface. By increasing the annealing temperature, the epitaxiality of CoSi2 improves due to the increased lateral growth rate of the CoSi2. However, annealing above 900 °C impairs the CoSi2 crystallinity because the interlayered Ta loses its function as a diffusion barrier due to ...

Film Growth Kinetics of Chemical Vapor Deposition of Copper from Cu ( HFA ) 2

Copper films have been grown by chemical vapor deposition (CVD) from copper (II) hexafluoroacetylacetonate, Cu(HFA)[sub 2], in a cold wall, vertical flow reactor with pure hydrogen and a mixture of hydrogen (75%)/argon (25%). The quantitatively measured operating conditions were 10 Torr total pressure, 300 to 400 C substrate temperature, and 70 to 85 C precursor temperature. Film growth rates were between 100 to 1,000 [angstrom]/min depending on processing conditions. The copper film growth rate was 0.5 order in both precursor and hydrogen concentration. A deposition temperature of about 300 C was needed to obtain significant film growth. Only surface impurities were detected in copper film. Any impurities below the surface were under the detection limits of Auger electron spectroscopy analysis. Resistivities of 2.0--3.0 [mu][Omega] cm were routinely obtained. Two mechanisms are proposed for the growth of copper films by CVD using Cu(HFA)[sub 2] which are consistent with the experimental observations and those in the literature.

Diffusion barrier performance of chemically vapor deposited TiN films prepared using tetrakis‐dimethyl‐amino titanium in the Cu/TiN/Si structure

We investigated diffusion barrier performance of chemical vapor deposition (CVD) TiN films prepared using tetrakis‐dimethyl‐amino titanium, Ti[N(CH3)2]4, to copper in the Cu/TiN/Si structure. The in situ treatment of the TiN films using N2/H2 plasma was found to significantly improve barrier performance against copper diffusion. The plasma‐treated TiN films were stable up to 650 °C but as‐deposited TiN films showed an evidence of copper diffusion into silicon even after annealing at 550 °C. The causes of the different effectiveness as a copper diffusion barrier of the two types of the CVD TiN films were discussed.

Low Pressure Chemically Vapor Deposited Copper Films for Advanced Device Metallization

This paper describes systematic experiments on the characteristics of copper films prepared by chemical vapor deposition from measured gas-phase concentrations of copper(II) hexafluoroacetylacetonate, Cu(HFA) 2 , in a cold-wall-type vertical flow reactor with pure hydrogen or a mixture of hydrogen (15%) /argon (25%). The films were analyzed by Auger electron spectroscopy (AES), scanning electron microscopy (SEM), x-ray diffraction (XRD), and spectrophotometry. Under the conditions investigated, film growth rates were 100-1000 A/min depending on processing conditions. The films deposited at 310-390 o C were pure, and the resistivity of the films was routinely near 2.0 μΩ cm when film thickness was 5000 A or more

Characteristics of atomic layer deposited TiO2 films and their photocatalytic activity

Titanium dioxide thin films were grown by atomic layer deposition (ALD) at 100–250 °C with tetrakis-dimethyl-amido titanium, using H2O2 as a counter-reactant. We have explored the effects of deposition temperature and the reactant pulse and purge times on the film growth rate to optimize the ALD process of TiO2. The film growth rate decreased with growth temperature below 175 °C, but was saturated to 0.28A∕cycle at 175–250 °C. All the as-deposited films were highly pure, and the root-mean-square roughness was less than 2.5% of the film thickness. The films deposited at 150 °C and above were polycrystalline with an anatase structure, whereas those deposited at 125 ° C were amorphous. There was no change of crystal structure after annealing the crystalline films at temperatures of 450–650 °C. All the crystalline films were shown to have a photocatalytic activity in decomposing methylene blue in an aqueous solution. The films prepared at higher deposition temperatures were shown to have a better photocatalyt...

Stability of TiN Films Prepared by Chemical Vapor Deposition Using Tetrakis‐dimethylamino Titanium

The effect of in situ N{sub 2}/H{sub 2} plasma post-treatment on the stability of TDMAT-based CVD TiN films was studied. Post-treatment greatly improves the film stability in air regardless of conditions of the plasma treatment. Among the tested variables, the plasma exposure time strongly affects the resistivity and carbon content of the deposits. Longer treatment results in reduced carbon content and enhanced stability in air. With increasing treatment time, the resistivity decreased exponentially and then finally saturated at a certain value. At a fixed time for plasma treatment, increasing the N{sub 2}/H{sub 2} ratio provides better film stability compared to increasing RF power. However, no noticeable difference of carbon content in the film was observed with variation of RF power and the ratio of N{sub 2}/H{sub 2} at a fixed treatment time. An enhancement of film crystallinity was observed as plasma post-treatment.

SELECTIVE DEPOSITION OF COPPER BY CHEMICAL VAPOR DEPOSITION USING CU(HFA)2

The selectivity of chemical vapor deposition copper for metal or metallic substrates in preference to silicon dioxide was investigated systematically using copper (II) hexafluoroacetylacetonate, Cu(HFA)2, with pure hydrogen or hydrogen/argon mixtures (1:3) in a cold wall type vertical flow reactor as a function of measured total pressure (2–10 Torr), deposition temperature (310–390 °C), and inlet precursor mole fraction (0.008–0.09). The deposition temperature was found to be the most important parameter. Temperatures of 310–360 °C resulted in selective deposition under the above conditions. Auger electron spectroscopy depth profiles indicate the composition of the films. Some local nucleation of copper due to the surface imperfections on silicon oxide was observed. These studies help to clarify some discordant results reported in the literature by determining to a good approximation the conditions of temperature, pressure and gas phase composition under which selective deposition of copper was observed.

Nucleation of copper on TiW and TiN during chemical vapor deposition

Copper grows as continuous films on various silicides and metals at substrate temperatures of 310–385 °C, total pressures of 2–10 Torr, and precursor vessel temperatures of 60–80 °C (precursor mole fractions of 0.004–0.35) with hydrogen using copper (II) hexafluoroacetylacetonate [Cu(HFA)2] as the precursor. However, on TiW, TiW:N, and TiN substrates, that were previously exposed to air, copper formed only small crystalline aggregates, not continuous films, perhaps because of a thin surface layer of oxide. This conclusion was supported by Auger electron spectroscopy and scanning electron microscopy analyses.

Low Temperature Deposition of Tacn Films Using Pentakis(Diethylamido)Tantalum

TaCN films were deposited at low temperature (≤400 °C) by metallorganic chemical vapor deposition (MOCVD) using pentakis(diethylamido)tantalum (PDEAT) as a precursor. The activation energy of the surface reaction is about 0.79 eV and the maximum deposition rate is about 100 A/min at 350 °C. The resistivity of the as-deposited film decreases as the deposition temperature increases and the minimum value of resistivity obtained is 6000 μΩ-cm for the sample deposited at 400 °C. Major chemical elements in the films were detected as Ta, C, and N with some amounts of O by Auger electron spectroscopy (AES). By x-ray photoelectron spectroscopy (XPS), it is identified that the most of carbon in the films was bonded to Ta. The microstructural investigation using high resolution transmission electron microscopy reveals a nanocrystalline phase with an average grain size of about 30 A. Preliminary investigation of the diffusion barrier property for copper showed that the 300 A of TaCN diffusion barrier was failed after annealing at 500°C for 1 hr.

Dry sol-gel condensation of p-X-C6H4SiH3 (X = H, CH3, CH3O, F, Cl) to organosilica p-X-C6H4SiO3 using nickelocene.

The dry sol-gel reaction at toluene in ambient air atmosphere of p-X-C6H4SiH3 (X = H, CH3, CH3O, F, Cl) to p-C6H4SiO3 in high yield, catalyzed by nickelocene, is reported. The highest yield, molecular weight, polydispersity index, and TGA residue yield were obtained for p-Cl-C6H4SiH3. Some degree of unreacted Si-H bonds still remained in the gel because of steric reason. All the insoluble gels adopt an amorphous structure with a smooth surface. A plausible mechanism for the dry sol-gel reaction was suggested.