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:

  1. 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.

  2. 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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