Growth and crystallization of TiO2 thin films by atomic layer deposition using a novel amido guanidinate titanium source and tetrakis-dimethylamido-titanium

Research output: Contribution to journalResearch articleContributedpeer-review

Contributors

  • Marcel Reiners - , Jülich Research Centre (Author)
  • Ke Xu - , Ruhr University Bochum (Author)
  • Nabeel Aslam - , Jülich Research Centre (Author)
  • Anjana Devi - , Ruhr University Bochum (Author)
  • Rainer Waser - , Jülich Research Centre, RWTH Aachen University (Author)
  • Susanne Hoffmann-Eifert - , Jülich Research Centre (Author)

Abstract

We studied the growth of TiO2 by liquid injection atomic layer deposition (ALD) utilizing two different amide-based titanium sources, tetrakis-dimethylamido-titanium [(NMe2)4-Ti, TDMAT] and its recently developed derivative, tris-(dimethylamido)-mono-(N,N′- diisopropyl-dimethyl-amido-guanidinato)-titanium {[(N-iPr)2NMe 2]Ti(NMe2)3, TiA3G1}, with water vapor as counterreactant. A clear saturation of growth with an increasing precursor supply was found for TDMAT between 150 and 300 C and for TiA3G1 between 150 and 330 C. Representative growth per cycle (GPC) values at 250 C were 0.041 and 0.044 nm/cycle, respectively. Compared to that of TDMAT, ALD of TiA3G1 exhibited a significantly higher stability in the GPC values up to 300 C coinciding with an improved temperature stability of the precursor. Both processes showed a minimum of the growth rate as a function of temperature. In all cases, the residual carbon and nitrogen contents of the TiO2 films were <3 atom %. Conformal growth was demonstrated on three-dimensional pinhole structures with an aspect ratio of around 1:30. Deposition temperatures of ≤200 C led to quasi-amorphous films. At higher growth temperatures, the anatase phase developed, accompanied by the brookite and/or the rutile phase depending on process conditions, deposition temperature, and film thickness.

Details

Original languageEnglish
Pages (from-to)2934-2943
Number of pages10
JournalChemistry of materials
Volume25
Issue number15
Publication statusPublished - 13 Aug 2013
Peer-reviewedYes
Externally publishedYes

Keywords

Keywords

  • atomic layer deposition (ALD), brookite, crystallization, crystallization kinetics, anatase, guanidinate, rutile, titanium oxide (TiO)