Metal-organic chemical vapor deposition of high-k dielectric Ce–Al–O layers from various metal-organic precursors for metal–insulator–metal capacitor applications A. Abrutis a, ⁎, M. Lukosius b , M. Skapas a , S. Stanionyte a , V. Kubilius a , Ch. Wenger b , A. Zauner c a Dept. of General and Inorganic Chemistry, Vilnius University, 24 Naugarduko, LT-03225 Vilnius, Lithuania b IHP, ImTechnologiepark 25, 15230, Frankfurt Oder, Germany c Air Liquide CRCD, 1 Chemin de la Porte des Loges, 78354 Les Loges-en-Josas, France abstract article info Article history: Received 9 July 2012 Received in revised form 22 March 2013 Accepted 22 March 2013 Available online 2 April 2013 Keywords: High-k dielectrics Cerium aluminate Thin films Metal-organic chemical vapor deposition Annealing Crystallization Metal–insulator–metal applications The possibilities to grow thin layers of high-k dielectric CeAlO 3 by pulsed injection metal-organic chemical vapor deposition using different metal-organic (MO) precursors have been investigated. Three pairs of MO precursors were studied for the growth of the films: Ce (IV) and Al(III) 2,2,6,6-tetramethylheptane-3,5-dionates, Ce tetrakis(1-methoxy-2-methyl-2-propoxide)-diethylaluminumethoxide and tris(isopropylcyclopentadienyl) cerium-tris(diethylamino)aluminum. Under optimized conditions, all three pairs of investigated precursors enabled the growth of close to stoichiometric Ce–Al–O films at reasonably low temperatures, 400–450 °C, how- ever, crystalline CeAlO 3 phase was not present in as-deposited layers. Films were grown on Si(100) and Si(100)/TiN substrates. Two kinds of TiN electrodes were used — amorphous TiN (15–30 nm thick) and crystal- line TiN (70–100 nm thick) layers, grown by chemical vapor deposition and physical vapor deposition techniques, respectively. The pure tetragonal CeAlO 3 phase was crystallized in films by a short annealing in Ar or N 2 at 800– 850 °C. Required annealing conditions (temperature and annealing duration) depended on the selected precur- sors and substrates. Thermomechanical degradation of Si/TiN/Ce–Al–O structures was observed by Scaning Elec- tron Microscopy after the annealing of the samples. Lower degradation degree was observed for structures with a thin amorphous TiN layer. © 2013 Elsevier B.V. All rights reserved. 1. Introduction The development of wireless communication products needs fur- ther development of metal–insulator–metal (MIM) capacitors, as they are one of the key passive elements in radio frequency and analog/ mixed signal integrated circuits. Due to the down scaling of the technol- ogy node, the decrease of the on-chip capacitors size becomes essential in integrated circuits for next generation technologies. This may be achieved by the increase of capacitance density per unit area, where the replacement of now used SiO 2 or Si 3 N 4 by alternative dielectrics with higher k value is one of the most promising approaches. Various potential high-k dielectrics have been developed by mixing two binary oxides, expecting superior properties compared to the single oxides. CeAlO 3 is one of the attractive candidates among mixed oxides due to its high bulk permittivity of ~3000 [1]. Amorphous thin films containing mixtures of CeO 2 and Al 2 O 3 have been deposited by physical deposition techniques like pulsed laser deposition on Si [2] or molecular beam deposition on Si/TiN [3]. These amorphous layers exhibited smooth surface and rather promising dielectric constant in the range of 10–20. An efficient way to increase the permittivity of the dielectric mate- rial is the crystallization of a grown amorphous film by post deposi- tion annealing. However, the stability of the dielectric layer and layer/ electrode stack at high annealing temperature is a key issue for MIM capacitor integration. Crucial effect on the performance of MIM capaci- tors has a metal electrode. It has to exhibit high conductivity and suit- able work function as well as chemical inertness and thermal stability, especially when higher temperature is necessary for the deposition or annealing of the dielectric layer/electrode stack. Titanium nitride is known as a good candidate for the role of electrode in MIM stacks. For the development of next generation technologies, a suitable de- position technique should be chosen for the growth of dielectric layer/ electrode stack. Metal-organic chemical vapor deposition (MOCVD) and atomic layer deposition (ALD) are ones of the most attractive tech- niques due to good compositional control for ternary oxides, high uniformity of films, good doping control and conformal step coverage on non-planar device geometries. In this article we present the systematic results on the growth by Pulsed-Injection MOCVD (PI-MOCVD) technique of dielectric Ce–Al–O layers on Si/TiN substrates for MIM applications. Tris(2,2,6,6- tetramethylheptane-3,5-dionato)aluminum (Al(thd) 3 ), diethyl- aluminumethoxide (Et 2 Al(OEt)) and tris(diethylamino)aluminum (Al(NEt 2 ) 3 ) were used in this work as Al precursors, tetrakis (2,2,6,6-tetramethylheptane-3,5-dionato)cerium (Ce(thd) 4 ), cerium Thin Solid Films 536 (2013) 68–73 ⁎ Corresponding author. Tel.: +370 52193173; fax: +370 52330987. E-mail address: adulfas.abrutis@chf.vu.lt (A. Abrutis). 0040-6090/$ – see front matter © 2013 Elsevier B.V. All rights reserved. http://dx.doi.org/10.1016/j.tsf.2013.03.045 Contents lists available at SciVerse ScienceDirect Thin Solid Films journal homepage: www.elsevier.com/locate/tsf