Metal–insulator–metal capacitors with MOCVD grown Ce–Al–O as a dielectric

• Published in: Microelectronic engineering 2011-07, Vol.88 (7), p.1529-1532
• Main Authors: Lukosius, M., Baristiran-Kaynak, C., Abrutis, A., Skapas, M., Kubilius, V., Zauner, A., Ruhl, G., Wenger, Ch
• Format: Article
• Language: English
• Subjects: Applied sciences; Ce–Al–O; Chemical vapor deposition (including plasma-enhanced cvd, mocvd, etc.); Compound structure devices; Condensed matter: electronic structure, electrical, magnetic, and optical properties; Cross-disciplinary physics: materials science; rheology; Dielectric; Dielectric, amorphous and glass solid devices; Electronic structure and electrical properties of surfaces, interfaces, thin films and low-dimensional structures; Electronic transport in interface structures; Electronics; Exact sciences and technology; Materials science; Metal-nonmetal contacts; Methods of deposition of films and coatings; film growth and epitaxy; MIM; MOCVD; Physics; Semiconductor electronics. Microelectronics. Optoelectronics. Solid state devices
• ISSN: 0167-9317; 1873-5568
• DOI: 10.1016/j.mee.2011.03.044

Ce–Al–O thin films were prepared on 70 nm TiN/Si(1 0 0) substrates by pulsed injection metal organic chemical vapor deposition (PI-MOCVD) for metal–insulator–metal (MIM) applications. Depositions were carried out at 400 °C using two separate Ce and Al precursors. In order to get Ce–Al–O films with different stoichiometry, Al 2O 3 and CeO 2 were mixed with different Ce:Al precursors’ ratios. According to the XRD analysis, the as deposited films were amorphous if more aluminum was injected than cerium, and crystalline – if they are cerium rich. Electrical properties have been investigated in MIM capacitors after e-beam evaporation of Au top electrodes. Oxides possess a dielectric constant of 10–20 in combination with leakage current densities as low as 10 −5 A/cm 2 at −2 V. The post deposition annealing (PDA) at 600 °C and 850 °C in N 2 for 5 min lead to the diffusion of Ti from TiN bottom electrode and formation of the rutile TiO 2 phase. Nevertheless, CeAlO 3 films were obtained if the ratio of injected Ce:Al was 1:1. The k values increased to 60 in this case, but the leakage current density worsened to 10 −3 A/cm 2 at −2 V.