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Title: Incomplete elimination of precursor ligands during atomic layer deposition of zinc-oxide, tin-oxide, and zinc-tin-oxide

For atomic layer deposition (ALD) of doped, ternary, and quaternary materials achieved by combining multiple binary ALD processes, it is often difficult to correlate the material properties and growth characteristics with the process parameters due to a limited understanding of the underlying surface chemistry. In this work, in situ Fourier transform infrared (FTIR) spectroscopy was employed during ALD of zinc-oxide, tin-oxide, and zinc-tin-oxide (ZTO) with the precursors diethylzinc (DEZ), tetrakis(dimethylamino)tin (TDMASn), and H 2O. The main aim was to investigate the molecular basis for the nucleation delay during ALD of ZTO, observed when ZnO ALD is carried out after SnO 2 ALD. Gas-phase FTIR spectroscopy showed that dimethylamine, the main reaction product of the SnO 2 ALD process, is released not only during SnO 2 ALD but also when depositing ZnO after SnO 2, indicating incomplete removal of the ligands of the TDMASn precursor from the surface. Transmission FTIR spectroscopy performed during ALD on SiO 2 powder revealed that a significant fraction of the ligands persist during both SnO 2 and ZnO ALD. These observations provide experimental evidence for a recently proposed mechanism, based on theoretical calculations, suggesting that the elimination of precursor ligands is often not complete. In addition,more » it was found that the removal of precursor ligands by H 2O exposure is even less effective when ZnO ALD is carried out after SnO 2 ALD, which likely causes the nucleation delay in ZnO ALD during the deposition of ZTO. Furthermore, the underlying mechanisms and the consequences of the incomplete elimination of precursor ligands are discussed.« less
Authors:
 [1] ;  [1] ;  [1] ;  [1]
  1. Stanford Univ., Stanford, CA (United States). Dept. of Chemical Engineering
Publication Date:
Grant/Contract Number:
SC0004782
Type:
Accepted Manuscript
Journal Name:
Journal of Chemical Physics
Additional Journal Information:
Journal Volume: 146; Journal Issue: 5; Journal ID: ISSN 0021-9606
Publisher:
American Institute of Physics (AIP)
Research Org:
Stanford Univ., Stanford, CA (United States). Dept. of Chemical Engineering
Sponsoring Org:
USDOE Office of Science (SC)
Country of Publication:
United States
Language:
English
Subject:
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
OSTI Identifier:
1464924
Alternate Identifier(s):
OSTI ID: 1322424