TEM investigation of silicon carbide wafers with reduced micropipe density |
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| Authors: | S E Saddow T E Schattner M Shamsuzzoha S V Rendakova V A Dmitriev |
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| Affiliation: | (1) Department of Electrical & Computer Engineering, Mississippi State University, Box 9571, 39762 Mississippi State, MS, USA;(2) Department of Metallurgical Engineering and School of Mines Energy Development, University of Alabama, 35487 Tuscaloosa, AL;(3) PhysTech WBG Research Group, Ioffe Institute, 194021 St. Petersburg, Russia;(4) Howard University, MCRSE, 20059 Washington, D.C., USA;(5) TDI, Inc., 20877 Gaithersburg, MD, USA |
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| Abstract: | A technique to reduce the micropipe density in SiC substrates by first filling in the defects and then growing an LPE layer
on the filled material has been developed by TDI. LPE growth in SiC is known to result in poor surface morphology, namely
step-bunching due to the off-axis substrate orientation. Chemical vapor deposition (CVD) growth experiments on SiC substrates
with reduced micropipe density using a cold-wall CVD reactor resulted in a significant improvement in the surface morphology.
Although preliminary device results are encouraging, the exact nature of the filled micropipes nor the impact of growing CVD
epitaxial layers on LPE SiC had not been fully characterized. We have preformed transmission electron microscopy (TEM) measurements
to evaluate the crystallographic properties of the CVD/LPE and LPE/substrate interface. It was observed that no new dislocations
were nucleated at the LPE/CVD interface. Although a micropipe was not located in the samples characterized, a tilt of 1.5°
was observed between the LPE layer and the substrate. In addition, dislocations were observed to propagate through the LPE
layer from the substrate which are most likely the 1C close-core screw dislocations common to SiC hexagonal substrates. |
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| Keywords: | Reduced micropipe LPE CVD epitaxial layer TEM micropipe defect dislocation |
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