Microstructure and chemical analysis of Hf-based high-k dielectric layers in metal–insulator–metal capacitors

• Published in: Thin solid films 2010-05, Vol.518 (15), p.4467-4472
• Main Authors: Thangadurai, P., Mikhelashvili, V., Eisenstein, G., Kaplan, W.D.
• Format: Article
• Language: English
• Subjects: Applied sciences; Capacitors; Condensed matter: structure, mechanical and thermal properties; Cross-disciplinary physics: materials science; rheology; Deposition; Devices; Dielectrics; EDS; EELS; Electrodes; Electronic equipment and fabrication. Passive components, printed wiring boards, connectics; Electronics; Exact sciences and technology; Gates; HAADF; Hafnium; High-k; HRTEM; Materials science; Methods of deposition of films and coatings; film growth and epitaxy; Microstructure; MIM capacitors; Physics; Spectrum imaging; Structure and morphology; thickness; Surfaces and interfaces; thin films and whiskers (structure and nonelectronic properties); Tantalum oxides; Thin film structure and morphology; Vapor phase epitaxy; growth from vapor phase
• ISSN: 0040-6090; 1879-2731
• DOI: 10.1016/j.tsf.2010.03.002

The microstructure and chemistry of the high-k gate dielectric significantly influences the performance of metal–insulator–metal (MIM) and metal–oxide–semiconductor devices. In particular, the local structure, chemistry, and inter-layer mixing are important phenomena to be understood. In the present study, high resolution and analytical transmission electron microscopy are combined to study the local structure, morphology, and chemistry in MIM capacitors containing a Hf-based high-k dielectric. The gate dielectric, bottom and gate electrodes were deposited on p-type Si(100) wafers by electron beam evaporation. Four chemically distinguishable sub-layers were identified within the dielectric stack. One is an unintentionally formed 4.0 nm thick interfacial layer of Ta 2O 5 at the interface between the Ta electrode and the dielectric. The other three layers are based on HfN x O y and HfTiO y , and intermixing between the nearby sub-layers including deposited SiO 2. Hf-rich clusters were found in the HfN x O y layer adjacent to the Ta 2O 5 layer.