Paper Title:
Direct Observation of Dielectric Breakdown Spot in Thermal Oxides on 4H-SiC(0001) Using Conductive Atomic Force Microscopy
  Abstract

The dielectric breakdown mechanism in 4H-SiC metal-oxide-semiconductor (MOS) devices was studied using conductive atomic force microscopy (C-AFM). We performed time-dependent dielectric breakdown (TDDB) measurements using a line scan mode of C-AFM, which can characterize nanoscale degradation of dielectrics. It was found that the Weibull slope () of time-to-breakdown (tBD) statistics in 7-nm-thick thermal oxides on SiC substrates was much larger for the C-AFM line scan than for the common constant voltage stress TDDB tests on MOS capacitors, suggesting the presence of some weak spots in the oxides. Superposition of simultaneously obtained C-AFM topographic and current map images of SiO2/SiC structure clearly demonstrated that most of breakdown spots were located at step bunching. These results indicate that preferential breakdown at step bunching due to local electric field concentration is the probable cause of poor gate oxide reliability of 4H-SiC MOS devices.

  Info
Periodical
Materials Science Forum (Volumes 645-648)
Edited by
Anton J. Bauer, Peter Friedrichs, Michael Krieger, Gerhard Pensl, Roland Rupp and Thomas Seyller
Pages
821-824
DOI
10.4028/www.scientific.net/MSF.645-648.821
Citation
K. Kozono, T. Hosoi, Y. Kagei, T. Kirino, S. Mitani, Y. Nakano, T. Nakamura, T. Shimura, H. Watanabe, "Direct Observation of Dielectric Breakdown Spot in Thermal Oxides on 4H-SiC(0001) Using Conductive Atomic Force Microscopy", Materials Science Forum, Vols. 645-648, pp. 821-824, 2010
Online since
April 2010
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$32.00
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