1. Conformal Formation of(GeTe2)(1âx)(Sb2Te3)xLayers by AtomicLayer Deposition for Nanoscale Phase ChangeMemories.
- Author
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Eom, Taeyong, Choi, Seol, Choi, Byung Joon, Lee, Min Hwan, Gwon, Taehong, Rha, Sang Ho, Lee, Woongkyu, Kim, Moo-Sung, Xiao, Manchao, Buchanan, Iain, Cho, Deok-Yong, and Hwang, Cheol Seong
- Subjects
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ATOMIC layer deposition , *PHASE transitions , *RANDOM access memory , *NONVOLATILE memory , *THIN films , *CRYSTAL growth , *GERMANIUM compounds , *TEMPERATURE effect - Abstract
Phase change random access memory appears to be the strongestcandidatefor next-generation high density nonvolatile memory. The fabricationof ultrahigh density phase change memory (â«1 Gb) depends heavilyon the thin film growth technique for the phase changing chalcogenidematerial, most typically containing Ge, Sb and Te (GeâSbâTe).Atomic layer deposition (ALD) at low temperatures is the most preferredgrowth method for depositing such complex materials over surfacespossessing extreme topology. In this study, [(CH3)3Si]2Te and stable alkoxy-Ge (Ge(OCH3)4) and alkoxy-Sb (Sb(OC2H5)3) metalâorganic precursors were used to deposit variouslayers with compositions lying on the GeTe2âSb2Te3tie lines at a substrate temperature as lowas 70 °C using a thermal ALD process. The adsorption of Ge precursorwas proven to be a physisorption type while other precursors showeda chemisorption behavior. However, the adsorption of Ge precursorwas still self-regulated, and the facile ALD of the pseudobinary solidsolutions with composition (GeTe2)(1-x)(Sb2Te3)xwereachieved. This chemistry-specific ALD process was quite robust againstprocess variations, allowing highly conformal, smooth, and reproduciblefilm growth over a contact hole structure with an extreme geometry.The detailed ALD behavior of binary compounds and incorporation behaviorsof the binary compounds in pseudobinary solid solutions were studiedin detail. This new composition material showed reliable phase changeand accompanying resistance switching behavior, which were slightlybetter than the standard Ge2Sb2Te5material in the nanoscale. The local chemical environment was similarto that of conventional Ge2Sb2Te5materials. [ABSTRACT FROM AUTHOR]
- Published
- 2012
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