Properties of atomic-vapor and atomic-layer deposited Sr, Ti, and Nb doped Ta₂O₅ Metal-Insulator-Metal capacitors

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• 作者：M. Lukosius^a ; ^{lukosius@ihp-microelectronics.com} ; C. Baristiran Kaynak^a ; S. Kubotsch^a ; T. Blomberg^b ; G. Ruhl^c ; Ch. Wenger^a
• 关键词：MIM ; Ta2O5 ; Ti&ndash ; Ta&ndash ; O ; Sr&ndash ; Ta&ndash ; O ; Nb&ndash ; Ta&ndash ; O ; AVD ; ALD
• 刊名：Thin Solid Films
• 出版年：2012
• 期刊代码：78_00406090
• 类别：ph
• 出版时间：1 May, 2012
• 卷：520
• 期：14
• 页码：4576-4579
• 文件大小：664 K

摘要

Atomic Vapor Deposition and Atomic Layer Deposition techniques were applied for the depositions of Ta₂O₅, Ti-Ta-O, Sr-Ta-O and Nb-Ta-O oxide films for Metal-Insulator-Metal (MIM) capacitors used in back-end of line for Radio Frequency applications. Structural and electrical properties were studied. Films, deposited on the TiN bottom electrodes, in the temperature range of 225-400 掳C, were amorphous, whereas the post deposition annealing at 600 掳C resulted in the crystallization of Nb-Ta-O films. Electrical properties of MIM structures, investigated after sputtering Au top electrodes, revealed that the main characteristics were different for each oxide. On one hand, Ti-Ta-O based MIM capacitors possessed the highest dielectric constant (50), but the leakages currents were also the highest (~ 10^鈭?#xA0;5 A/cm² at 鈭?#xA0;2 V). On the other hand, Sr-Ta-O showed the lowest leakage current densities (~ 10^鈭?#xA0;9 A/cm² at 鈭?#xA0;2 V) as well as the smallest capacitance-voltage nonlinearity coefficients (40 ppm/V²), but the dielectric constant was the smallest (20). The highest nonlinearity coefficients (290 ppm/V²) were observed for Nb-Ta-O based MIM capacitors, although relatively high dielectric constant (40) and low leakage currents (~ 10^鈭?#xA0;7 A/cm² at 鈭?#xA0;2 V) were measured. Temperature dependent leakage-voltage measurements revealed that only Sr-Ta-O showed no dependence of leakage current as a function of the measurement temperature.