ALD of ZrO2 Thin Films Exploiting Novel Mixed Alkylamido-Cyclopentadienyl Precursors

Jaakko Niinistö 1Kaupo Kukli 1,2Mikko Ritala 1Markku Leskela 1Nicolas Blasco 3Audrey Pinchart 3Christophe Lachaud 3Nadia Laaroussi 3Christian Dussarrat 4

1. Department of Chemistry, University of Helsinki, A. I. Virtasen aukio 1, Helsinki FIN-00014, Finland
2. Department of Physics, University of Tartu, Tähe Street, Tartu 51010, Estonia
3. Air Liquide Research and Development, 1 Chemin de la Porte des Loges, Jouy-en-Josas 78354, France
4. Air Liquide Laboratories, Wadai 28, Tsukuba 300-4247, Japan

Abstract

ALD has high potential in microelectronics for the growth of high permittivity (high-k) films to replace SiO2-based solutions as insulators for complementary metal oxide semiconductor devices and dynamic random access memory capacitors. For alternative high-k materials the leading solutions include the oxides of Hf and Zr. For ALD of these materials, alkylamides have gained wide interest as precursors. The suitable atomic layer deposition (ALD) growth temperature range for the Zr- alkylamide processes, e.g TEMAZ (Zr(NEtMe)4) is rather limited to obtain excellent film properties. Thermal decomposition of TEMAZ begins to play a major role in growth mechanism when the applied growth temperature exceeds 275ºC, thus preventing the ALD-type growth mode and resulting in poor film uniformity. However, the relatively high growth rate favors the alkylamide precursors over many other options, such as dicyclopentadienyl (Cp)-type precursors that have been investigated.

In this presentation we introduce a novel class of zirconium precursors, combining the beneficial characteristics of alkylamides (physical state, volatility, reactivity) with the enhanced thermal stability of the cyclopentadienyl precursors. We compare several precursors from this novel class and TEMAZ thermal properties (TGA/DT/DSC, vapor pressure) and ALD behavior. All precursors reported in this work provide comparable volatility and higher thermal stability than TEMAZ. In addition, one of the precursors reported in this work, namely Zr(EtCp)(NMe2)3 provides comparable growth rate (0.9 Å/cycle with ozone as the oxygen source) and film properties with TEMAZ. Properties of films obtained with other similar mixed Cp-alkylamido-precursors are also discussed.

 

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Presentation: Oral at E-MRS Fall Meeting 2007, Symposium C, by Jaakko Niinistö
See On-line Journal of E-MRS Fall Meeting 2007

Submitted: 2007-05-21 13:36
Revised:   2009-06-07 00:44