AVS 53rd International Symposium
    Plasma Science and Technology Wednesday Sessions
       Session PS2+TF-WeM

Paper PS2+TF-WeM5
In Situ Studies of Reaction Mechanisms during Plasma-Assisted Atomic Layer Deposition of Al@sub 2@O@sub 3@

Wednesday, November 15, 2006, 9:20 am, Room 2011

Session: Plasma Deposition
Presenter: S.B.S. Heil, Eindhoven University of Technology, The Netherlands
Authors: S.B.S. Heil, Eindhoven University of Technology, The Netherlands
P. Kudlacek, Eindhoven University of Technology, The Netherlands
E. Langereis, Eindhoven University of Technology, The Netherlands
R. Engeln, Eindhoven University of Technology, The Netherlands
M.C.M. Van De Sanden, Eindhoven University of Technology, The Netherlands
W.M.M. Kessels, Eindhoven University of Technology, The Netherlands
Correspondent: Click to Email
Extending the atomic layer deposition (ALD) technique with plasma processes (i.e., plasma-assisted ALD or PA-ALD) opens up new routes that are difficult to attain by pure thermal ALD. In particular the ability to deposit high-quality oxide films at low substrate temperatures using an O@sub2@ plasma has recently expanded the interest in ALD from solely semiconductor manufacturing to upcoming fields such as photovoltaics and flexible electronics. However, for PA-ALD the reaction mechanisms leading to film formation have not been extensively studied and especially for the reactions occurring during the plasma step several questions still remain unanswered. In this contribution, we present an in situ study of the PA-ALD process of Al@sub2@O@sub3@ from Al(CH@sub3@)@sub3@ (trimethylaluminum, TMA) and O@sub2@ plasma. Employing a combination of quartz crystal microbalance (QCM), quadrupole mass spectrometry (QMS), and optical emission spectroscopy (OES) an insight into the plasma species, reaction products, and surface chemistry is gained. For example, QMS showed that during the plasma step H@sub2@O and CO@sub2@ are formed from the surface CH@sub3@ groups in a combustion like reaction. This is supported by time-resolved OES in which the consumption of oxygen species and the emission by excited CO molecules were detected until the process reached saturation (<0.5 s). From QCM and QMS measurements it was determined that during the precursor step the TMA reacts mainly bifunctionally with the surface OH groups splitting of ~1.8 CH@sub3@ ligands as CH@sub4@. QCM measurements were correlated with in situ spectroscopic ellipsometry giving more detailed information about film growth during PA-ALD of Al@sub2@O@sub3@. The combustion like reaction occurring in the deposition of Al@sub2@O@sub3@ is expected to be generic for plasma-assisted ALD processes of oxides from metalorganic precursors.