Influence of Substrates on the Nucleation and Growth Behaviors of Ge2Sb2Te5 Films by Combined Plasma-Enhanced Atomic Layer and Chemical Vapor Deposition

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• 作者：Byung Joon Choi ; Seol Choi ; Taeyong Eom ; Seung Wook Ryu ; Deok-Yong Cho ; Jaeyeong Heo ; Hyeong Joon Kim ; Cheol Seong Hwang ; Yoon Jung Kim ; Suk Kyoung Hong
• 刊名：Chemistry of Materials
• 出版年：2009
• 出版时间：June 23, 2009
• 年：2009
• 卷：21
• 期：12
• 页码：2386-2396
• 全文大小：505K
• 年卷期：v.21,no.12(June 23, 2009)
• ISSN：1520-5002

文摘

This study concerned the effect of the substrate on the nucleation and growth behavior of Ge₂Sb₂Te₅ (GST) thin films deposited by a combination of plasma-enhanced chemical vapor deposition (for Sb and Te) and plasma-enhanced atomic layer deposition (for Ge) processes at wafer temperatures ranging from 100 to 200 °C using Ge(i-C₄H₉)₄, Sb(i-C₃H₇)₃, and Te(i-C₃H₇)₂ as the Ge, Sb, and Te precursors, respectively. Several oxide and nitride layers that were formed on the Si substrate were concerned as substrates. The nucleation of the GST films on the SiO₂, Si₃N₄, and ZrO₂ substrates was seriously retarded (long incubation cycles) compared to those on the TiN and TiO₂ substrates, where smooth film growth with negligible incubation cycles was achieved. The GST film did not grow at all on the HfO₂ substrate. The reason for the enhanced nucleation and growth properties of GST on the TiO₂ and TiN (partially oxidized) substrates was related to the formation of a GeO₂ phase and the charge exchange effect of a partially reduced Ti oxide. On the other hand, the SiO₂ surface remained insulating during deposition, which inhibited GST nucleation. The different nucleation behaviors also influenced the crystallization behavior of the film, which in turn altered the saturated film growth rates. It is believed that the crystallized GST surface reduced the activation energy for the chemisorption of the precursors, which enhanced the saturated growth rate.