Sung-tae Kim

Evaluation of Novel Sr Precursors for Atomic Layer Deposition of SrO Thin Film

Atomic layer deposition (ALD) process to deposit SrO film using novel Sr precursor – Sr (Methoxy-TetramethylHeptadiene)2 was estimated. Fig.1 showed the chemical structure of the synthesized Sr(MTHD)2. Fig. 2 showed thermal gravimetric analysis results of Sr(MTHD)2 and commercially used Sr (Tetra-Methyl Hetadiene)2. 50 % precursor evaporation temperature (T50) of Sr (MTHD)2 was 330 C, which was 30 C lower than that of Sr(TMHD)2. Liquid delivery system with flash evaporator was used to transport the precursors to substrate. The precursors were dissolved in Tetra Hydro Furan (THF) to prevent clogging during the delivery process. Ozone was used as a reactant to deposit SrO. It was found that thickness uniformity range of SrO film on Si wafer was less than 2 %. The deposition rate of SrO film using new Sr precursor was 0.4 A/cycle, which was almost same regardless of substrate temperatures up to 400 C. High vapor pressure and good thermal stability of new Sr precursor make it promising candidates for ALD precursors to deposit SrTiO3, aSrTiO3. Fig.1. Chemical structure of Sr(MTHD)2

Metal Organic Chemical Vapor Deposition of (Ba,Sr)RuO 3 Conductive Oxide Film for (Ba,Sr)TiO 3

(Ba,Sr)RuO 3 films have been tailored as an electrode for (Ba,Sr)TiO 3 which is a promising material for the high dielectric in ULSI DRAM. In this study, BSR conductive oxide film was deposited on 4-inch Si-wafer by metal organic chemical vapor deposition (MOCVD) using single cocktail source for the practical device application. Liquid delivery system (LDS) and vaporization cell were utilized for the delivery and vaporization of single cocktail source, respectively. The source feeding rate was controlled by liquid mass flow controller(LMFC). Ba(METHD) 2 , Sr(METHD) 2 , Ru(METHD) 3 precursors and solvent [n-butylacetate(C 6 H 12 O 2 )] were mixed for single coctail source. Among the various deposition parameters, control of the oxygen flow rate turned out to be crucial for determining the phase formation, resistivity, and the composition ratio of (Ba,Sr)RuO 3 films. Highly (110)-textured (Ba,Sr)RuO 3 film was obtained when Ar/O 2 ratio was 100/300sccm with the source flow rate of 0.075sccm. Oxygen annealing of (Ba,Sr)RuO 3 films enhanced the properties of the films without changing the (110) texture, and the resistivity of the resulted film was 2440 w z cm.

Characterization of (Ba,Sr)RuO 3 Films Deposited by Metal-organic Chemical Vapor Deposition

(Ba, Sr)RuO3 oxide electrodes have been studied for high dielectric (Ba, Sr)TiO3 film in DRAM capacitors. Metal organic chemical vapor deposition (MOCVD) is used for large-scale deposition and provides better step coverage properties. In this work, methoxyethoxytetramethylheptanedionate (METHD) precursor and solvent [n-butylacetate(C6H12O2)] were mixed together into a single solution source. Post deposition annealing is carried out in oxygen atmosphere using rapid thermal annealing (RTA) to investigate the effect of organic impurities such as carbon during deposition. After annealing, resistivity of the BSR film decreased drastically compared to the as-deposited film. X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) analysis were used to describe this phenomenon accurately. The decrease in carbonate with increasing annealing time was confirmed by XRD analysis. 2004 Elsevier B.V. All rights reserved.