Conformality of Pb(Zr,Ti)O[sub 3] Films Deposited on Trench Structures Having Submicrometer Diameter and Various Aspect Ratios

Nagai, Atsushi; Minamidate, Jun; Asano, Gouji; Choi, Chong Won; Cho, Choong-Rae; Park, Young-Soo; Funakubo, Hiroshi

doi:10.1149/1.2137470

Cited by 15 publications

(13 citation statements)

References 10 publications

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“…This distribution of cation composition is better than the large distribution of more than 30% reported for films deposited by MOCVD. 1,3,4 Although the process was not an ideally self-regulated one, the very slow gradient of the Pb/ Ti ratio against V͑Pb͒ shown in Fig. 6 could be the reason for better cation composition uniformity compared to MOCVD.…”

Section: B Incubation Periodmentioning

confidence: 99%

“…Recent studies have indicated a serious problem in that multicomponent oxide films deposited over 3D structures by MOCVD exhibit nonuniformity in cation composition, although film thickness appears to be uniform over the complex structure. [1][2][3][4] In MOCVD, surface reaction limiting deposition, where the deposition rate depends only on the substrate temperature, has been a common approach to achieving a homogeneous 3D coverage. However, at a mutual deposition temperature, not every precursor necessarily decomposes under the surface-reaction limiting condition.…”

Section: Introductionmentioning

confidence: 99%

“…9,10 Due to ongoing reductions in the feature size and switching voltage, a conformal deposition of very thin films on 3D capacitor structures was required. 1,2 Thin films of PbTiO x were deposited in a combination of two self-limiting binary processes of ALD-TiO x and PbO. 11,12 The deposition rates of the cations and the incubation period were investigated as a function of the input of precursors using planar substrates.…”

Section: Introductionmentioning

confidence: 99%

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Growth of ternary PbTiOx films in a combination of binary oxide atomic layer depositions

Watanabe

Hoffmann‐Eifert

et al. 2007

Journal of Applied Physics

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Ternary PbTiOx films were deposited at 240°C on Pt-covered Si substrates using a combination of liquid injection atomic layer depositions of binary TiOx and PbO films. Ti(OC3H7)2(C11H19O2)2 [Ti(Oi−Pr)2(DPM)2] and Pb(C11H19O2)2 [Pb(DPM)2] dissolved in ethylcyclohexane and H2O were used as source materials. The deposition rates of Pb and Ti were enhanced in the ternary process compared to their binary processes under comparable deposition conditions. The Pb∕Ti ratio of PbTiOx films saturated with an increase in Ti precursor input, while it continued to increase with an increasing Pb precursor input. The self-regulated growth nature of the Pb–O layer in the binary film growth was lost in the mixed PbTiOx process as a result of interaction with the predeposited Ti–O layer. It was confirmed that for the PbTiOx film to grow on Pt substrates, an initial incubation period is required. Both Pb–O and Ti–O layers shared a common incubation period of up to ten sequences. The incubation period was shortened by increasing the input of Pb precursor. It was independent of the input of the Ti precursor and the order of precursor supply. This variable incubation period was considered as a potential key issue for growing stoichiometric and uniform multicomponent films over three-dimensional (3D) structures. The order of precursor supply affected the effective deposition rate after the incubation period. A sequence starting with a Ti precursor injection showed a higher growth rate than a sequence that started with a Pb precursor supply. A PbTiOx film was deposited on a 3D substrate precoated with an Ir layer to demonstrate the uniformity in film thickness and cation composition. Although the present PbTiOx process does not have an ideal wide-process window in the cation composition, the PbTiOx film showed uniform coverage and the distribution of cation composition over the hole structure was within ±10%.

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Section: B Incubation Periodmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Growth of ternary PbTiOx films in a combination of binary oxide atomic layer depositions

Watanabe

Hoffmann‐Eifert

et al. 2007

Journal of Applied Physics

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“…Pb(C 11 4 [tetrakis (1-methoxy-2-methyl-2-propoxy) zirconium, Zr(MMP) 4 ] (Asahi Denka Kogyo K. K.), and Ti(OC(CH 3 ) 2 CH 2 OCH 3 ) 4 [tetrakis(1-methoxy-2-methyl-2-propoxy)titanium, Ti(MMP) 4 ] (Asahi Denka Kogyo K. K.) were used as the respective Pb, Zr, and Ti source materials [10,11]. Ethylcyclohexane and O 2 gas were used as a solvent and as an oxidant, respectively.…”

Section: Methodsmentioning

confidence: 99%

Trial for Making Three Dimensional PZT Capacitor for High Density Ferroelectric Random Access Memory

Funakubo

Nagai

Minamidate

et al. 2006

Integrated Ferroelectrics

Self Cite

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Three dimensional capacitors of Pb(Zr,Ti)O 3 [PZT] together with the Ru electrodes were tried to deposit by metal organic chemical vapor deposition for realizing high density ferroelectric random access memory (FeRAM). Good conformability was obtained for both of CVD-Ru and PZT layers on the trenched substrates by optimizing the deposition conditions. In addition, PZT films deposited on Ru bottom electrode showed the good compositional conformability. Finally we demonstrated the Ru/PZT/Ru three dimensional capacitor. These data accelerate the development of three dimensional PZT capacitors.

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“…However, uniform coverage both with respect to film thickness and cation composition is not always achieved. This issue can be seen for Pb(Zr,Ti)Ox [PZT] films deposited by MOCVD over 3D structures [1,2]. PZT thin films with large switching charges are used in ferroelectric random access memories (FeRAMs) [3].…”

Section: Introductionmentioning

confidence: 99%

Atomic Layer Deposition of Pb(Zr,Ti)O<inf>x</inf>, Thin Films by a Combination of Binary Atomic Layer Deposition Processes

Watanabe¹,

Hoffmann‐Eifert²,

Waser³

et al. 2006

2006 IEEE International Symposium on the Applications of Ferroelectrics

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After an evaluation of Zr precursor, quatemary Pb(Zr,Ti)Ox [PZT] films were prepared by a combination of binary atomic layer deposition (ALD) processes. ZrOx films were deposited on Pt/TiOx/SiOx/Si substrates using liquid injection ALD. Zr(CiiH1902)4 [Zr(DPM)4] dissolved in ethylcyclohexane (ECH) with a concentration of 0.1 M and water were used as precursor and oxidant, respectively. According to the Arrhenius plot for the deposition rate of ZrOx films at various deposition temperatures, the Zr precursor appeared to start marked thermal decomposition at a deposition temperature of 360°C. Below this thermal decomposition temperature, a saturated deposition rate of ZrOx films against input of Zr precursor was confirmed. The saturated deposition rate was about 5-6x 10-12 mol/cm2 cycle at a deposition temperature of 300°C. Subsequently, binary ALD processes of TiOx and PbO films, whose self-regulated growth mode has been already confirmed, were combined with the ZrOx process into multi-precursor ALD of PZT films. Ti(OC3H7)2(CIIH1902)2 [Ti(Oi-Pr)2(DPM)2] and Pb(C11H1902)2 [Pb(DPM)2] dissolved in ECH with a concentration of 0.1 M were used for PZT film preparation as well as Zr(DPM)4. Unit sequences described as 1 x(Pb-O) -2x(Ti-O) -nx(Zr-O) were repeated to deposit PZT films at 240°C. In the PZT process, the deposition rates of all cations were higher than those in their binary processes. The Pb/(Zr+Ti) and Zr/(Zr+Ti) ratio was adjusted by repeating the number of Zr-O cycles in a sequence. As-deposited PZT films were amorphous. Crystalline PZT films were obtained after annealing at 650°C, and the PZT crystal showed a preferred (100)/(001) orientation.

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Conformality of Pb(Zr,Ti)O[sub 3] Films Deposited on Trench Structures Having Submicrometer Diameter and Various Aspect Ratios

Cited by 15 publications

References 10 publications

Growth of ternary PbTiOx films in a combination of binary oxide atomic layer depositions

Growth of ternary PbTiOx films in a combination of binary oxide atomic layer depositions

Trial for Making Three Dimensional PZT Capacitor for High Density Ferroelectric Random Access Memory

Atomic Layer Deposition of Pb(Zr,Ti)O<inf>x</inf>, Thin Films by a Combination of Binary Atomic Layer Deposition Processes

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