Improving the dielectric constant of Al₂O₃ by cerium substitution for high-k MIM applications

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• 作者：Rakesh Sohal ; Grzegorz Lupina ; Olaf Seifarth ; Peter Zaumseil ; Christian Walczyk ; Thomas Schroeder
• 关键词：High-k dielectric ; Cerium aluminate ; Thin film growth ; Molecular beam deposition ; X-ray photoelectron spectroscopy
• 刊名：Surface Science
• 出版年：2010
• 出版时间：15 February 2010
• 年：2010
• 卷：604
• 期：3-4
• 页码：276-282
• 全文大小：815 K

文摘

Process compatible high-k dielectric thin films are one of the key solutions to develop high performance metal–insulator–metal (MIM) structures for future microelectronic devices. Engineered cerium–aluminate (Ce_xAl_2–xO₃) thin films were deposited on titanium nitride metal electrodes by electron-beam co-evaporation of ceria and alumina in a molecular beam deposition chamber. X-ray photoelectron spectroscopy clearly reveals that Ce cations can be stabilized in the 3+ valence state in Ce_xAl_2–xO₃ up to x = 0.7 by accommodation in the alumina host matrix. Higher Ce content was observed to result in cerium dioxide segregation in cerium aluminate matrix, probably due to the chemical tendency of Ce cations to exist rather in the 4+ than in the 3+ state. Electrical characterization of the X-ray amorphous Ce_0.7Al_1.3O₃ films reveals a dielectric constant value of about 11 and leakage current lower than 10⁻⁴ A/cm². No parasitic low-k interface formation between the high-k Ce_0.7Al_1.3O₃ film and the TiN metal electrode is detected.