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20060401: Quantitative defect investigation and
micropipe formation in SiC
Micropipe formation in SiC have been the subject
of long-standing scientific controversy; understanding and
eliminating micropipe are of great technological significance and
crucial to a broad range of SiC-based applications. One main reason
for the deficiency in understanding micropipe formation is due to
the fact that there are less effective quantitative study and
statistically sound data which can be used to validate different
theories. The relatively low density of closed-core screw
dislocations (1000s cm-2) make it difficult for modern instruments,
especially the high-resolution transmission electron microscope, to
capture the individual dislocation structure, while the large scale
of micropipes (with diameters of submicron or microns) make it
difficult to image a whole micropipe at an atomic level.
Recently MaxMile Technologies has developed an
approach to quantitatively investigate superscrew dislocations
including elementary screw
dislocations and micropipes
in a SiC single crystal. This method can precisely determine the
magnitude and sign of Burgers vectors of each screw dislocation or
micropipe over an entire wafer. A systematic and extensive
quantitative investigation has been performed to understand the
nature of superscrew dislocations in 4H
and 6H SiC.
The revealed results do not support the former
micropipe formation theories which are based on the coalescence or
mergence of elementary dislocations or micropipes with same-sign
Burgers vectors. A mechanism of mismatched coalescence between
multiple nucleation sites is also proposed to understand the
formation of micropipes in SiC.
The method and micropipe formation mechanism will
be further used for micropipe-free SiC material development.
For more information, please visit:
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Publication:
(a)
Superscrew Dislocations in Silicon Carbide: Dissociation,
Aggregation and Formation, Journal of Applied Physics,
Vol.99, 2006: 063514; (b)
A Method to Determine Superscrew
Dislocation Structure in Silicon Carbide, Material Science and
Engineering B, Vol. 129, 2006: 216-221.
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Application note: (a)
A method to determine the Burgers vector value of superscrew
dislocations in SiC at the wafer level (b)
Micropipe formation and its driving force issues in SiC growth
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