Metal-Induced Nickel Silicide Nanowire Growth Mechanism in the Solid State Reaction
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0910-A21-07
Metal-Induced Nickel Silicide Nanowire Growth Mechanism in the Solid State Reaction Joondong Kim1,2, Jong-Uk Bae1, Wayne A. Anderson1, Hyun-Mi Kim3, and Ki-Bum Kim3 1
Electrical Engineering, University at Buffalo, State University of New York, Buffalo, NY, 14260 2
Materials Science and Engineering, Pohang University of Science and Technology, Pohang, 790-784, Korea, Republic of 3
Materials Science and Engineering, Seoul National University, Seoul, 151-742, Korea, Republic of ABSTRACT A unique nanowire growth was accomplished at 575 oC by metal-induced growth (MIG). That is a spontaneous reaction between metal and Si. The deposited metal worked as a catalyst layer to grow nanowires in the solid-state. Various metals (Ni, Co, and Pd) were used in MIG nanowire fabrication and the Ni-induced case was successful in demonstrating that metal species should be a dominant mover in nanowire growth. Transmission electron microscopy investigation was performed to observe the nanowire growth direction. The Ni to Si composition was studied by energy dispersive spectroscopy showing the Ni diffusion inside the nanowire as well as the Ni silicide layer. INTRODUCTION Nanowires (NW) are attractive as 1-dimensitonal building blocks, such as nanoscale devices [1] and nanoscale interconnections [2]. The bottom-up approach provides an effective way in nanoelectronics to be applied in high level integrated circuits [3]. Several nanowire growth mechanisms were reported, such as vapor-liquid-solid (VLS), solid-liquid-solid (SLS), and solid-solid (SS) types. The VLS type was first presented by R.S. Wagner and R. G Treuting [4,5] which is also the most popular method to grow NWs today. The liquid catalyst acts as the energetically favored entity for absorbing gas-phase reactants [6]. The high temperature for NW growth has been relieved to 320 – 600 oC by use of gas type Si sources such as SiCl4 or SiH4 with Au [7-10]. The use
of Au catalyst and a gaseous Si source contributes to reduce process temperature. Otherwise, it needs a high temperature close or above 1000 oC to liquefy the catalyst and Si [11-14]. Recently, the SLS synthesis has been reported. Metal catalyst coated Si prevents direct forming of vaporized Si atoms but results in liquid droplets of Si and metal even at a high temperature of 900 – 950 oC [15,16]. The SS type was also claimed to grow NWs at 1050 oC by simple annealing in a CH4:H2 mixture gas. In this mechanism, the metal particles are observed on the tip of NWs, different from the SLS mechanism [17]. A unique NW growth mechanism was reported by the metal-induced growth (MIG) method, initiated in our laboratory. The MIG NWs were grown at 575 oC, which is the lowest NW fabrication temperature by solid-state NW fabrication [18]. In this report, the MIG NW growth mechanism was investigated by structural and chemical analysis. EXPERIMENTAL DETAILS Ni, Co, or Pd as a catalyst metal was thermally evaporated onto a SiO2 layer coated Si (100) substrate. A 150 – 200 nm thick SiO2 was deposited by plasma enhanced c
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