A Novel Ruthenium Precursor for MOCVD without Seed Ruthenium Layer
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A Novel Ruthenium Precursor for MOCVD without Seed Ruthenium Layer Tetsuo Shibutami, Kazuhisa Kawano, Noriaki Oshima, Shintaro Yokoyama1 and Hiroshi Funakubo1 TOSOH Corporation, Tokyo Research Center, 2743-1, Hayakawa, Ayase-shi, Kanagawa2521123, Japan 1 Department of Innovative and Engineered Materials Interdisciplinary Graduated School of Science and Engineering Tokyo Institute of Technology, 4259, Nagatsuda-cho, Midori-ku, Yokohama, Kanagawa226-8502, Japan ABSTRACT Ruthenium thin films were deposited on SiO2/Si substrates at 275 – 400 oC by metalorganic chemical vapor deposition (MOCVD) using liquid precursor (2.4dimethylpentadienyl)(ethylcyclopentadienyl)ruthenium [Ru(DMPD)(EtCp) DMPD: 2.4dimethylpentadienyl EtCp: etylcyclopentadienyl]. Deposition characteristics of the films were compared with those using bis(ethylcyclopentadienyl)ruthenium. The decomposition temperature of Ru(DMPD)(EtCp) was 80 oC lower than Ru(EtCp)2. Both films consisted of Ru single phase for all deposition temperature range and showed an resistivity bellow 20 µΩcm for the films deposited above 300 oC. The initial nucleation of Ru films from Ru(DMPD)(EtCp) precursor was smaller in size and denser than that from Ru(EtCp)2. The deposition process from Ru(DMPD)(EtCp) has much shorter incubation time than that from Ru(EtCp)2. INTRODUCTION Ruthenium thin film is a promising electrode material for high-dielectric capacitor such as tantalum pentoxide (Ta2O5) and barium strontium titanate [(Ba,Sr)TiO3] in Gbit-scale dynamic random access memories (DRAMs), because it has low resistivity, excellent chemical stability and good dry etching property. There have been several attempts to deposit Ru and RuO2 films by metalorganic chemical vapor deposition (MOCVD) using Bis(cyclopentadienyl)ruthenium [Ru(Cp)2 Cp:Cyclopentadienyl], and Tri(acetylacetonate)rutehnium [Ru(C5H7O2)3] [1], Tri(dipivaloylmethanate)ruthenium [Ru(DPM)3 DPM:Dipivaloylmethanate] [2,3], Tri(octanedionate)ruthenium [Ru(OD)3 OD:Octanedionate] [4,5] and Bis(ethylcyclopentadienyl)ruthenium [Ru(EtCp)2 EtCp:Ethylcyclopentadienyl] [6,7] precursor. Among those precursors, Ru(EtCp)2 has attracted attention because it has high vapor pressure and was liquid as state with low viscosity (approximately 5cP) at room temperature. However, this precursor had some drawbacks such as the fact that it has long incubation time at the initial stage of the growth [8,9]. In the present study, the novel precursor of (dimethylpentadienyl)(ethylcyclopentadienyl)ruthenium [Ru(DMPD)(EtCp) DMPD:dimethylpetadienyl] with liquid as state having low viscosity (approximately 6cP) at room temperature was prepared and used for Ru films deposition by MOCVD. In the present study, the deposition characteristics and the properties of the Ru films deposited from Ru(DMPD)(EtCp) were compared with those from Ru(EtCp)2. Molecular structure of Ru(DMPD)(EtCp) and Ru(EtCp)2 are shown in Figures 1(a) and 1(b) respectively.
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(a)
(b) Ru
Ru
Figure 1. Molecular structure of (a) Ru(DMPD)(EtCp) and (b) Ru(EtCp)2. EXPERI
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