(A) study on $SrTiO_3$ thin films deposited by plasma-enhanced atomic layer deposition for DRAM capacitor dielectric = PEALD법으로 증착된 DRAM capacitor 유전체용 $SrTiO_3$ 박막의 특성에 관한 연구

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The downscaling of the DRAM device is necessary to achieve higher speed with less power consumption. It is getting difficult to meet the new requirements with the existing $SiO_2$ or $Si_3N_4$ due to their low dielectric constants and tunneling leakage currents through the thin layers. For this reason, high-$\textit{k}$ materials enabling high-k and low leakage currents with physically thicker film have received considerable attention. Among the candidate for DRAM capacitor dielectrics, $SrTiO_3$ is a promising candidate for giga-bit scale dynamic random access memory (DRAM) capacitors because of its high dielectric constant, high breakdown strength and good thermal stability. $SrTiO_3$ films were deposited on 20 nm-Ru/25 nm-TiN/p-type Si (100) substrates by plasma-enhanced atomic layer deposition at a deposition temperature of 225℃ and a deposition pressure of 3 Torr using 0.2M $Sr(DPM)_2$ dissolved in butyl acetate and TTIP as precursors and $O_2$ plasma as an oxidant. SrO and $TiO_2$ films were grown separately to investigate the ALD characteristics. The thickness per cycle of SrO and $TiO_2$ are saturated to 0.054 nm/cycle 0.036 nm/cycle at 225℃, respectively. The composition of STO films was controlled by changing the number of each precursor cycles, and stoichiometric $SrTiO_3$ films were obtained when one super-cycle consisted of six $TiO_2$ cycles and seven SrO cycles. The deposited-$SrTiO_3$ films were crystallized after annealing at 600℃ for 10min under $N_2$ ambient and the dependence of the dielectric constant on $SrTiO_3$ film thickness was investigated for less 50 nm-thick $SrTiO_3$ films after the annealing process at 600℃ for 10 min under $N_2$ ambient. The dielectric constants of the films having thickness higher than 20 nm were not as sensitive to the film thickness with a relatively constant value of about 65. However, the dielectric constants of the films with thickness under 15 nm were dramatically decreased with decreasing the fil...
Advisors
Kang, Sang-Wonresearcher강상원researcher
Description
한국과학기술원 : 신소재공학과,
Publisher
한국과학기술원
Issue Date
2009
Identifier
309285/325007  / 020037364
Language
eng
Description

학위논문(박사) - 한국과학기술원 : 신소재공학과, 2009.2, [ xiv, 134 p. ]

Keywords

atomic layer deposition; thin films; dielectric; SrTiO3; 원자층증착법; 유전박막

URI
http://hdl.handle.net/10203/49662
Link
http://library.kaist.ac.kr/search/detail/view.do?bibCtrlNo=309285&flag=dissertation
Appears in Collection
MS-Theses_Ph.D.(박사논문)
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