title: Comparison of the Atomic Layer Deposition of Tantalum Oxide Thin Films Using Ta(NtBu)(NEt2)3, Ta(NtBu)(NEt2)2Cp, and H2O.
abstract: The growth characteristics of Ta2O5thin films by atomic layer deposition (ALD) were examined using Ta(NtBu)(NEt2)3(TBTDET) and Ta(NtBu)(NEt2)2Cp (TBDETCp) as Ta-precursors, wheretBu, Et, and Cp represent tert-butyl, ethyl, and cyclopentadienyl groups, respectively, along with water vapor as oxygen source. The grown Ta2O5films were amorphous with very smooth surface morphology for both the Ta-precursors. The saturated ALD growth rates of Ta2O5films were 0.77 Å cycle-1at 250 °C and 0.67 Å cycle-1at 300 °C using TBTDET and TBDETCp precursors, respectively. The thermal decomposition of the amido ligand (NEt2) limited the ALD process temperature below 275 °C for TBTDET precursor. However, the ALD temperature window could be extended up to 325 °C due to a strong Ta-Cp bond for the TBDETCp precursor. Because of the improved thermal stability of TBDETCp precursor, excellent nonuniformity of ∼2% in 200 mm wafer could be achieved with a step coverage of ∼90% in a deep hole structure (aspect ratio 5:1) which is promising for 3-dimensional architecture to form high density memories. Nonetheless, a rather high concentration (∼7 at. %) of carbon impurities was incorporated into the Ta2O5film using TBDETCp, which was possibly due to readsorption of dissociated ligands as small organic molecules in the growth of Ta2O5film by ALD. Despite the presence of high carbon concentration which might be an origin of large leakage current under electric fields, the Ta2O5film using TBDETCp showed a promising resistive switching performance with an endurance cycle as high as ∼17 500 for resistance switching random access memory application. The optical refractive index of the deposited Ta2O5films was 2.1-2.2 at 632.8 nm using both the Ta-precursors, and indirect optical band gap was estimated to be ∼4.1 eV for both the cases.
authors.affiliation: Department of Materials Science and Engineering and Inter-University Semiconductor Research Center, Seoul National University , Seoul 151-744, Korea.
authors.forename: Seul Ji
authors.initials: SJ
authors.lastname: Song
authors.affiliation: Department of Materials Science and Engineering and Inter-University Semiconductor Research Center, Seoul National University , Seoul 151-744, Korea.
authors.forename: Taehyung
authors.initials: T
authors.lastname: Park
authors.affiliation: Department of Materials Science and Engineering and Inter-University Semiconductor Research Center, Seoul National University , Seoul 151-744, Korea.
authors.forename: Kyung Jean
authors.initials: KJ
authors.lastname: Yoon
authors.affiliation: Department of Materials Science and Engineering and Inter-University Semiconductor Research Center, Seoul National University , Seoul 151-744, Korea.
authors.forename: Jung Ho
authors.initials: JH
authors.lastname: Yoon
authors.affiliation: Department of Materials Science and Engineering and Inter-University Semiconductor Research Center, Seoul National University , Seoul 151-744, Korea.
authors.forename: Dae Eun
authors.initials: DE
authors.lastname: Kwon
authors.affiliation: Air Liquide Laboratories Korea, Suite 176, Yonsei Engineering Research Park, 50 Yonsei-ro, Seodaemun-gu, Seoul 120-749, Korea.
authors.forename: Wontae
authors.initials: W
authors.lastname: Noh
authors.affiliation: Air Liquide Laboratories Korea, Suite 176, Yonsei Engineering Research Park, 50 Yonsei-ro, Seodaemun-gu, Seoul 120-749, Korea.
authors.forename: Clement
authors.initials: C
authors.lastname: Lansalot-Matras
authors.affiliation: Air Liquide Laboratories Korea, Suite 176, Yonsei Engineering Research Park, 50 Yonsei-ro, Seodaemun-gu, Seoul 120-749, Korea.
authors.forename: Satoko
authors.initials: S
authors.lastname: Gatineau
authors.affiliation: Pohang Accelerator Laboratory, Pohang 37673, Korea.
authors.forename: Han-Koo
authors.initials: HK
authors.lastname: Lee
authors.affiliation: Dr. S.S.Bhatnagar University Institute of Chemical Engineering and Technology, Panjab University , Chandigarh 160 014, India.
authors.forename: Sanjeev
authors.identifier: http://orcid.org/0000-0003-3123-9906
authors.initials: S
authors.lastname: Gautam
authors.affiliation: Department of Physics, Chonbuk National University , Jeonju 54896, Korea.
authors.forename: Deok-Yong
authors.identifier: http://orcid.org/0000-0001-5789-8286
authors.initials: DY
authors.lastname: Cho
authors.affiliation: Department of Physics and Division of Energy Systems Research, Ajou University , Suwon 16499, Korea.
authors.forename: Sang Woon
authors.identifier: http://orcid.org/0000-0002-6448-5444
authors.initials: SW
authors.lastname: Lee
authors.affiliation: Department of Materials Science and Engineering and Inter-University Semiconductor Research Center, Seoul National University , Seoul 151-744, Korea.
authors.forename: Cheol Seong
authors.identifier: http://orcid.org/0000-0002-6254-9758
authors.initials: CS
authors.lastname: Hwang
keywords: Ta(NtBu)(NEt2)2Cp (TBDETCp); Ta(NtBu)(NEt2)3 (TBTDET); Ta2O5; atomic layer deposition (ALD); resistive switching