Atomic layer deposition of SrTiO3 films with cyclopentadienyl-based precursors for metal-insulator-metal capacitors

Woongkyu Lee; Jeong Hwan Han; Woojin Jeon; Yeon Woo Yoo; Sang Woon Lee; Seong Keun Kim; Chang Hee Ko; Clement Lansalot-Matras; Cheol Seong Hwang

doi:10.1021/cm304125e

Atomic layer deposition of SrTiO₃ films with cyclopentadienyl-based precursors for metal-insulator-metal capacitors

Woongkyu Lee, Jeong Hwan Han, Woojin Jeon, Yeon Woo Yoo, Sang Woon Lee, Seong Keun Kim, Chang Hee Ko, Clement Lansalot-Matras, Cheol Seong Hwang

Dept. of Materials Science & Engineering

Research output: Contribution to journal › Article › peer-review

81 Scopus citations

Abstract

The characteristics of the atomic layer deposition (ALD) of SrTiO ₃ (STO) films were examined for metal-insulator-metal capacitors, with Cp-based precursors Sr(iPr₃Cp)₂ and Cp*Ti(OMe)₃ [Cp* = C₅(CH₃) ₅] employed as the Sr and Ti precursors, respectively. While the Sr precursor has a higher reactivity toward oxygen on the Ru substrate compared with another Ti precursor, with a 2,2,6,6-tetramethyl-3,5-heptanedionato ligand, which results in the highly Sr excessive STO film, the enhanced reactivity of the present Ti precursor suppressed the unwanted excessive incorporation of Sr into the film. A possible mechanism for the Sr overgrowth and retardation is suggested in detail. By controlling the subcycle ratio of SrO and TiO ₂ layers, stoichiometric STO could be obtained, even without employing a deleterious reaction barrier layer. This improved the attainable minimum equivalent oxide thickness of the Pt/STO/RuO₂ capacitor to 0.43 nm, with acceptable leakage current density (∼8 × 10^-8 A/cm²). This indicates an improvement of ∼25% in the capacitance density compared with previous work.

Original language	English
Pages (from-to)	953-961
Number of pages	9
Journal	Chemistry of Materials
Volume	25
Issue number	6
DOIs	https://doi.org/10.1021/cm304125e
State	Published - 26 Mar 2013

Keywords

atomic layer deposition
capacitor
DRAM
Ru
RuO
SrTiO

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@article{74282e47a9344ecb836dfc58b1dbcb60,

title = "Atomic layer deposition of SrTiO3 films with cyclopentadienyl-based precursors for metal-insulator-metal capacitors",

abstract = "The characteristics of the atomic layer deposition (ALD) of SrTiO 3 (STO) films were examined for metal-insulator-metal capacitors, with Cp-based precursors Sr(iPr3Cp)2 and Cp*Ti(OMe)3 [Cp* = C5(CH3) 5] employed as the Sr and Ti precursors, respectively. While the Sr precursor has a higher reactivity toward oxygen on the Ru substrate compared with another Ti precursor, with a 2,2,6,6-tetramethyl-3,5-heptanedionato ligand, which results in the highly Sr excessive STO film, the enhanced reactivity of the present Ti precursor suppressed the unwanted excessive incorporation of Sr into the film. A possible mechanism for the Sr overgrowth and retardation is suggested in detail. By controlling the subcycle ratio of SrO and TiO 2 layers, stoichiometric STO could be obtained, even without employing a deleterious reaction barrier layer. This improved the attainable minimum equivalent oxide thickness of the Pt/STO/RuO2 capacitor to 0.43 nm, with acceptable leakage current density (∼8 × 10-8 A/cm2). This indicates an improvement of ∼25\% in the capacitance density compared with previous work.",

keywords = "atomic layer deposition, capacitor, DRAM, Ru, RuO, SrTiO",

author = "Woongkyu Lee and Han, \{Jeong Hwan\} and Woojin Jeon and Yoo, \{Yeon Woo\} and Lee, \{Sang Woon\} and Kim, \{Seong Keun\} and Ko, \{Chang Hee\} and Clement Lansalot-Matras and Hwang, \{Cheol Seong\}",

year = "2013",

month = mar,

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doi = "10.1021/cm304125e",

language = "English",

volume = "25",

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journal = "Chemistry of Materials",

issn = "0897-4756",

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T1 - Atomic layer deposition of SrTiO3 films with cyclopentadienyl-based precursors for metal-insulator-metal capacitors

AU - Lee, Woongkyu

AU - Han, Jeong Hwan

AU - Jeon, Woojin

AU - Yoo, Yeon Woo

AU - Lee, Sang Woon

AU - Kim, Seong Keun

AU - Ko, Chang Hee

AU - Lansalot-Matras, Clement

AU - Hwang, Cheol Seong

PY - 2013/3/26

Y1 - 2013/3/26

N2 - The characteristics of the atomic layer deposition (ALD) of SrTiO 3 (STO) films were examined for metal-insulator-metal capacitors, with Cp-based precursors Sr(iPr3Cp)2 and Cp*Ti(OMe)3 [Cp* = C5(CH3) 5] employed as the Sr and Ti precursors, respectively. While the Sr precursor has a higher reactivity toward oxygen on the Ru substrate compared with another Ti precursor, with a 2,2,6,6-tetramethyl-3,5-heptanedionato ligand, which results in the highly Sr excessive STO film, the enhanced reactivity of the present Ti precursor suppressed the unwanted excessive incorporation of Sr into the film. A possible mechanism for the Sr overgrowth and retardation is suggested in detail. By controlling the subcycle ratio of SrO and TiO 2 layers, stoichiometric STO could be obtained, even without employing a deleterious reaction barrier layer. This improved the attainable minimum equivalent oxide thickness of the Pt/STO/RuO2 capacitor to 0.43 nm, with acceptable leakage current density (∼8 × 10-8 A/cm2). This indicates an improvement of ∼25% in the capacitance density compared with previous work.

AB - The characteristics of the atomic layer deposition (ALD) of SrTiO 3 (STO) films were examined for metal-insulator-metal capacitors, with Cp-based precursors Sr(iPr3Cp)2 and Cp*Ti(OMe)3 [Cp* = C5(CH3) 5] employed as the Sr and Ti precursors, respectively. While the Sr precursor has a higher reactivity toward oxygen on the Ru substrate compared with another Ti precursor, with a 2,2,6,6-tetramethyl-3,5-heptanedionato ligand, which results in the highly Sr excessive STO film, the enhanced reactivity of the present Ti precursor suppressed the unwanted excessive incorporation of Sr into the film. A possible mechanism for the Sr overgrowth and retardation is suggested in detail. By controlling the subcycle ratio of SrO and TiO 2 layers, stoichiometric STO could be obtained, even without employing a deleterious reaction barrier layer. This improved the attainable minimum equivalent oxide thickness of the Pt/STO/RuO2 capacitor to 0.43 nm, with acceptable leakage current density (∼8 × 10-8 A/cm2). This indicates an improvement of ∼25% in the capacitance density compared with previous work.

KW - atomic layer deposition

KW - capacitor

KW - DRAM

KW - Ru

KW - RuO

KW - SrTiO

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ER -

Atomic layer deposition of SrTiO₃ films with cyclopentadienyl-based precursors for metal-insulator-metal capacitors

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