AVS 53rd International Symposium
    Electronic Materials and Processing Tuesday Sessions
       Session EM-TuA

Paper EM-TuA2
Growth of Epitaxial @gamma@-Al@sub 2@O@sub 3@ Films on 4H-SiC

Tuesday, November 14, 2006, 2:20 pm, Room 2003

Session: Materials for Power Electronics
Presenter: C.M. Tanner, University of California, Los Angeles
Authors: C.M. Tanner, University of California, Los Angeles
J. Lu, Uppsala University, Sweden
H.-O. Blom, Uppsala University, Sweden
J.P. Chang, University of California, Los Angeles
Correspondent: Click to Email
The development of epitaxial high-k gate dielectrics has the potential to improve the performance of SiC power MOSFETs by improving the interface and enabling operation at a higher electric field. Al@sub 2@O@sub 3@ (k = 10) is a promising candidate due to its large bandgap and demonstrated stability in several crystalline phases. Al@sub 2@O@sub 3@ thin films were grown on chemically mechanically polished n-type 4H-SiC (0001) by atomic layer deposition (ALD) at 200°C using trimethylaluminum and water vapor. The films were stoichiometric with low carbon incorporation as evaluated by in-situ X-ray photoelectron spectroscopy (XPS). The as-deposited Al@sub 2@O@sub 3@ films were amorphous as determined by in-situ reflection high-energy electron diffraction (RHEED). Upon annealing in N@sub 2@ at 1100°C, the film crystallized to the @gamma@-Al@sub 2@O@sub 3@ phase as observed by RHEED, high-resolution transmission electron microscopy (HRTEM) and X-ray diffraction (XRD). Based on the Fourier transform of the HRTEM image, an epitaxial relationship of @gamma@-Al@sub 2@O@sub 3@ (111) on 4H-SiC (0001) was observed in which @gamma@-Al@sub 2@O@sub 3@ (-110) was oriented with 4H-SiC (-12-10). This orientation was further confirmed by XRD analysis in which only the @gamma@-Al@sub 2@O@sub 3@ (111) and (222) peaks were observed. An abrupt interface of both amorphous and crystalline Al@sub 2@O@sub 3@ with 4H-SiC was determined by HRTEM. Capacitance-voltage (C-V) and current-voltage (I-V) measurements of 4H-SiC MOS capacitors fabricated with 200 Å Al@sub 2@O@sub 3@ dielectric films were performed to compare the dielectric constant, fixed charge, density of interface states, and breakdown properties of epitaxial @gamma@-Al@sub 2@O@sub 3@ films with respect to those of amorphous Al@sub 2@O@sub 3@ as well as state-of-the-art thermal silicon dioxides.