AVS 53rd International Symposium
    Nanometer-scale Science and Technology Wednesday Sessions
       Session NS+NM-WeA

Paper NS+NM-WeA8
SPM Nanolithography of ZrN Thin Films: Nitrogen-Enhanced Growth and Hollow Oxide Feature Formation

Wednesday, November 15, 2006, 4:20 pm, Room 2016

Session: Nanolithography and Patterning
Presenter: N. Farkas, The University of Akron
Authors: N. Farkas, The University of Akron
E.A. Evans, The University of Akron
R.D. Ramsier, The University of Akron
J.A. Dagata, National Institute of Standards and Technology
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A systematic study of the scanning probe microscope (SPM) oxidation of sputter-deposited ZrN thin films is presented. Based on data covering an extensive range of parameters such as exposure time, voltage, humidity and nitrogen content of the sputtering plasma, we propose a four-stage oxidation kinetics model for ZrN. We find that the heights of the oxide features are significantly larger when the films are prepared with substantial nitrogen content in the deposition plasma, whereas small nitrogen flow rates yield oxidation rates similar to Zr films. In the intrinsic part of the SPM oxidation, the oxide density increases until the volume of the oxide is about twice that of the consumed ZrN. Further oxide growth is sustainable, and in fact faster yet controlled, as the system crosses over from the space charge limited to a nitrogen-enhanced growth regime. Most striking and different from other material systems is that high-voltage SPM oxidation of ZrN generates micrometer high features that are an order of magnitude higher than the thickness of the films. Selective etching of the oxides and nitrides reveals that as the oxidation reaches the ZrN/silicon interface delamination occurs resulting in hollow oxide feature formation through stress-induced plastic flow. Interpretations of the underlying processes and film properties responsible for the unique behavior of ZrN in all regimes are provided along with an explanation for the observed non-linear voltage dependence.