Deposition of Cu and Ru Thin Films in Deep Nanotrenches/Holes Using Supercritical Carbon Dioxide

Abstract

Supercritical CO2 behaves like both a gas and a liquid, and posseses unique features such as nanopenetration capability, high diffusivity, and solvent ability. The technique described in this paper uses the supercritical CO2 as a reaction medium for thin film growth and realizes filling or coating of nanofeatures with conducting metals. In this paper, we demonstrate the possibilities of this technique in Cu and Ru thin film deposition. A basic approach to achieving Cu metallization of deca-nanometer trenches or vias were studied. Ru, a promising material for capacitor electrodes and also a new candidate for the next-generation Cu barrier, was successfully deposited and its deposition characteristics were studied. Filling capability and the possibility of conformal deposition were also demonstrated as well as the fabrication of a Cu\Ru stack.

Solubility of β-diketonate complexes for cobalt(III) and chromium(III) in supercritical carbon dioxide

“…Recently, scCO 2 has been used to make polymer-metal nanocomposites and metal thin films on the high-aspect-ratio surfaces of semiconductors. In these processes, the solubilities of metal complexes in scCO 2 are the essential data [1][2][3][4].…”

“…Many solubility data of metal acetylacetonate, which is the representative non-fluorinated ␤-diketonate metal complex in scCO 2 , have already been reported [5][6][7][8][9]. The solubilities of the metal complexes with fluorinated ligands were also measured, and the differences in solubilities between fluorinated and non-fluorinated metal complexes were discussed.…”

“…The solubilities of the metal complexes with fluorinated ligands were also measured, and the differences in solubilities between fluorinated and non-fluorinated metal complexes were discussed. Özel et al [10] measured the sulubilities of cobalt(II) acetylacetonate (Co(acac) 2 ) and cobalt(II) hexafluoroacetylacetonate (Co(hfacac) 2 ) in scCO 2 at 373 K and 40.5 MPa, and the results indicated that the solubility of Co(hfacac) 2 was about 4-fold higher than that of Co(acac) 2 . Moreover, M'Hamdi et al [11] studied the difference in solubility between yttrium(III) acetylacetonate (Y(acac) 3 ) and yttrium(III) hexafluoroacetylacetonate (Y(hfacac) 3 ) at 423 and 443 K and 12-22 MPa.…”

Measurement of the solubility of metal complexes in supercritical carbon dioxide using a UV–vis spectrometer

“…The SCFD technique takes advantage of particular characteristics of supercritical fluids, namely, low viscosity, high diffusivity and ability to control the solubility of solutes. This technique is expected to markedly improve the coat-ability, embedded quality, and deposition rate, and to increase the number of feasible precursors compared with existing methods, such as physical vapor deposition, chemical vapor deposition and atomic layer deposition [2][3][4].…”

“…Therefore, the critical properties must be estimated using a prediction method, such as the group contribution method, or they must be treated as adjustable parameters. Cross et al [8] correlated the solubility data of copper(II) acetylacetonate (Cu(acac) 2 ) in scCO 2 with a conventional mixing rule. The calculated results reproduced the experimental solubility data due to simultaneous determination of the critical temperature and pressure of Cu(acac) 2 , as well as the binary interaction parameter, k ij , by fitting the solubility data.…”