Plasma-assisted atomic layer deposition of ultrathin oxide and
metal films
Citation for published version (APA):
Kessels, W. M. M. (2009). Plasma-assisted atomic layer deposition of ultrathin oxide and metal films. 29th International Conference on Phenomena in Ionized Gases (ICPIG 2009), July 12-17, 2009, Cancún, México, Cancún, Mexico.
Document status and date: Published: 01/01/2009 Document Version:
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29th ICPIG, July 12-17, 2009, Cancún, México
Plasma-assisted atomic layer deposition of ultrathin oxide and metal films
U
W.M.M. KesselsUP
P
1
P
Department of Applied Physics, Eindhoven University of Technology, P.O. Box 513, 5600 MB Eindhoven, The Netherlands
U
w.m.m.kessels@tue.nl
Atomic layer deposition (ALD) is a thin film deposition method based on alternating saturated surface chemical reactions in which the self-limiting growth behavior allows for the deposition of ultrathin films with submonolayer control and with a high conformality on demanding 3D surface topologies. Since recently, the extension of the technique with plasma processes is actively being researched. These so-called plasma-assisted ALD (or plasma-enhanced ALD) processes can provide several potential benefits over thermal ALD such as (i) an enhanced growth rate, (ii) improved material properties, (iii) wider variety of thin film materials and properties, (iv) more process versatility, and (v) lower deposition temperatures (down to room temperature). These benefits make plasma-assisted ALD an attractive method for several applications also outside the traditional field of the semiconductor industry.
In this presentation first different plasma-assisted ALD configurations such as direct plasma, remote plasma, and radical enhanced ALD will described and the merits of the technique will be illustrated on the basis of results obtained for different metal oxide, metal nitride and metal films (Al2O3,
HfO2, TiO2, TiN, TaN, Pt, etc.). The versatility of the plasma-assisted ALD process will be
illustrated by several applications ranging from the semiconductor industry (high-density capacitor stacks), organic electronics (moisture permeation barriers), Li-ion battery technology (current collectors and diffusion barriers), and photovoltaics (surface passivation films). Generic insight into the plasma-assisted ALD surface reactions will be presented as obtained from mechanistic studies carried out by a variety of in situ techniques such as spectroscopic ellipsometry, transmission infrared spectroscopy, mass spectrometry, and optical emission spectroscopy.
0 50 100 150 200 0 100 200 300 0.44 A/cycle 0.79 A/cycle Al2O3 Ta2O5 TiO2 T h ic k n e s s ( A ) Number of cycles 1.17 A/cycle
Plasma-assisted ALD of several oxides from metalorganic precursor gases and O2 plasma: the
thickness can be controlled at the submonolayer-level by selecting the appropriate number of ALD cycles.
TiN film with a thickness of 55 nm deposited by plasma-assisted ALD (TiCl4 and H2-N2
plasma) in a Si trench with an aspect ratio of ~20 demonstrating the high conformality that can be achieved.
