Ligand Structure Effect on A Divalent Ruthenium Precursor for MOCVD
- PDF / 194,927 Bytes
- 6 Pages / 612 x 792 pts (letter) Page_size
- 36 Downloads / 216 Views
1155-C09-11
Ligand Structure Effect on A Divalent Ruthenium Precursor for MOCVD Kazuhisa Kawano1,2, Hiroaki Kosuge1, Noriaki Oshima1, Tadashi, Arii3, Yutaka Sawada4, and Hiroshi Funakubo2 1 TOSOH Corporation, Hayakawa 2743-1, Ayase, Kanagawa 252-1123, Japan. 2 Department of Innovative and Engineered Materials, Tokyo Institute of Technology, J2-43, 4259 Nagatuta-cho, Midori-ku, Yokohama, Kanagawa 226-8502, Japan. 3 Rigaku Corporation, 3-9-12 Matsubara, Akishima, Tokyo 196-8666, Japan. 4 Tokyo Polytechnic University, 1583 Iiyama, Atsugi, Kanagawa 243-0297, Japan
ABSTRACT Thermal properties of five divalent ruthenium precursors with three types of structures were examined by thermal analyses. Their volatilities and the relationships between their structure and thermal stability were compared by TG analysis. Precursor volatility was found to be inversely proportional to molecular weight. The DSC result showed that substituting a linear pentadienyl ligand for a cyclopentadienyl ligand decreased the thermal stability of a precursor and precursors could be liquefied by attaching an alkyl group longer than methyl group to a Cp ligand. As a result of TG-MS analyses for Ru(DMPD)(EtCp) and Ru(EtCp)2, 2,4-dimethyl-1,3pentadiene was found to be a thermolysis product of Ru(DMPD)(EtCp) though no thermolysis products of Ru(EtCp)2 were observed. These results show that the volatility and decomposition temperature of a divalent ruthenium precursor can be designed by adjusting the precursor’s structure.
INTRODUCTION Continuing growth of memory capacity for the requirement of miniaturizing semiconductor memory chips will require the exploitation of three-dimensional memory structures even if the capacitor dielectrics having a permittivity higher than that of SiO2, such as tantalum pentoxide [1] or strontium titanate, [2] are used. High-permittivity dielectrics for next-generation dynamic random access memory devices have therefore been investigated extensively. On the other hand, precious metals such as ruthenium, iridium, and platinum are candidates of electrode materials for these dielectrics, as well as their oxides. Among them, ruthenium was especially promising because of their low resistivity, excellent chemical stability, and good dry-etching properties. [36] As the deposition method, metalorganic chemical vapor deposition (MOCVD) has great advantages compared to the methods sputtering with regards to good throughput, composition control, and conformal deposition. [7] Among the variety of ruthenium precursors for MOCVD, the most promising one was bis(ethylcyclopentadienyl)ruthenium [Ru(EtCp)2] because of its high vapor pressure, low melting point, and high stability.[8] A serious problem, however, is a long “incubation time” and therefore then ruthenium seed layer by the sputter deposition is required to diminish the incubation time. [9] Our group has already reported that (2,4dimethylpentadienyl)(ethylcyclopentadienyl) ruthenium [Ru(DMPD)(EtCp)] showed much shorter incubation time than Ru(EtCp)2 and that metallic ruthenium f
Data Loading...
