Electrical and Structural Properties of Ruthenium Film Grown by Atomic Layer Deposition Using Liquid-Phase Ru(CO) 3 (C 6
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Electrical and Structural Properties of Ruthenium Film Grown by Atomic Layer Deposition using Liquid-Phase Ru(CO) 3 (C6H8) Precursor Sung-Hoon Chung1, Vladislav Vasilyev1, Evgeni Gorokhov1, Yong-Won Song1, and Hyuk-Kyoo Jang2 1 Department of Nano-Optics, Korea Polytechnic University, Shiheung, 429-793, Korea, Republic of 2 R&D Center, Mecharonics Co., Ltd., Pyontaek, 459-020, Korea, Republic of ABSTRACT We investigated effects of thermal annealing on Ru films deposited on the 8 inch Si substrates using a volatile liquid-phase Ru precursor, tricarbonyl-1,3-cyclohexadienyl ruthenium (Ru(CO)3(C6H8)) by an atomic layer deposition (ALD) technique. Structural and electrical properties of the films were characterized by scanning probe microscopy, X-ray diffractometry, and sheet resistance. Grazing incidence X-ray diffraction (GIXRD) patterns show typical Ru hexagonal polycrystalline peaks as annealing temperature was increased. At the highest annealing temperature condition, Ta = 700 oC electrical resistivity become six times less than in as-deposited films.
INTRODUCTION Ruthenium (Ru) film has been known as one of the most promising capacitor electrode material of ultra-large scale integrated dynamic random access memory (ULSI DRAM) device because of its low resistivity and high thermal stability [1,2]. Ru(EtCp)2 has been widely used as a Ru precursor so far [3]. However Ru film made with the precursor is vulnerable even to the temperature employed in the present DRAM fabrication, where process temperature of 600 oC is needed for fabricating a DRAM device with half-pitch, δ > 90 nm. We investigated thermal durability of Ru film with respect to the structural and electrical properties. Ru films were prepared by atomic layer deposition (ALD) technique on the 8 inch SiO2/Si substrate using a volatile liquid-phase Ru precursor, tricarbonyl-1,3-cyclohexadienyl ruthenium (Ru(CO)3(C6H8). Structural electrical characterizations were implemented by using field emission scanning electron microscopy (FE-SEM), scanning probe microscopy (SPM), grazing angle X-ray diffraction (GIXRD), four-point-probe measurement and energy dispersive X-ray analysis (EDX).
EXPERIMENT The Ru films were prepared by using an atomic layer deposition reactor equipped with a multichannel-type shower head and a dry pump (Edwards, IQDP-40). Argon gas was used for delivering and purging the Ru precursor and the reactant gas, NH3. The pulses of the Ru precursor, Ar, NH3 reactant, and Ar were consecutively introduced to the reactor and repeated 300 complete cycles with 1:3:1:3 sec as the pulse time and M(ArRu):50:50:50 sccm as the flow rate, where the argon carrier gas flow rate for the delivery of the Ru precursor, M(ArRu), was varied between 20 - 40 sccm. The gas ratios were kept constant with M(Ar):M(NH3):M(Ar) = 50:50:50 sccm. Further experiments to investigate the dependence of deposition rate on ruthenium dose were implemented as shown in figure 1. We note that figure 1 exhibits somewhat a rapid initial increase in deposition rate followed b
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