B.K. Tanner
X-ray asterism and the structure of cracks from indentations in silicon
Tanner, B.K.; Garagorri, J.; Gorostegui-Colinas, E.; Elizalde, M.R.; Allen, D.M.; McNally, P.J.; Wittge, J.; Ehlers, C.; Danilewsky, A.N.
Authors
J. Garagorri
E. Gorostegui-Colinas
M.R. Elizalde
D.M. Allen
P.J. McNally
J. Wittge
C. Ehlers
A.N. Danilewsky
Abstract
The asterism observed in white radiation X-ray diffraction images (topographs) of extended cracks in silicon is investigated and found to be associated with material that is close to breakout and surrounded by extensive cracking. It is a measure of the mechanical damage occurring when the fracture planes do not follow the low-index cleavage planes associated with the crystal structure. It is not related to a propensity for some cracked wafers to shatter during subsequent high-temperature processing. There is no correlation between crack morphology and alignment of an indenter with respect to the orientation of a silicon wafer, the cracks being generated from the apices of the indenter and having threefold symmetry for Berkovich indents and fourfold symmetry for Vickers indents. X-ray diffraction imaging (XRDI) of indents does not reveal this underlying symmetry and the images exhibit a very substantial degree of variation in their extent. This arises because the XRDI contrast is sensitive to the long-range strain field around the indent and breakout reduces the extent of this long-range strain field. Breakout is also detected in the loss of symmetry in the short-range strain field imaged by scanning micro-Raman spectroscopy. Weak fourfold symmetric features at the extremes of the images, and lying along <110> directions, are discussed in the context of slip generated below the room-temperature indents. Scanning electron microscopy imaging of the region around an indent during focused ion beam milling has permitted the three-dimensional reconstruction of the crack morphology. The surface-breaking Palmqvist cracks are found to be directly connected to the median subsurface cracks, and the presence of extensive lateral cracks is a prerequisite for material breakout at indenter loads above 200 mN. The overall crack shape agrees with that predicted from simulation
Citation
Tanner, B., Garagorri, J., Gorostegui-Colinas, E., Elizalde, M., Allen, D., McNally, P., …Danilewsky, A. (2016). X-ray asterism and the structure of cracks from indentations in silicon. Journal of Applied Crystallography, 49(1), 250-259. https://doi.org/10.1107/s1600576715024620
Journal Article Type | Article |
---|---|
Acceptance Date | Dec 22, 2015 |
Online Publication Date | Feb 1, 2016 |
Publication Date | Feb 1, 2016 |
Deposit Date | May 9, 2016 |
Publicly Available Date | May 18, 2016 |
Journal | Journal of Applied Crystallography |
Print ISSN | 0021-8898 |
Electronic ISSN | 1600-5767 |
Publisher | International Union of Crystallography |
Peer Reviewed | Peer Reviewed |
Volume | 49 |
Issue | 1 |
Pages | 250-259 |
DOI | https://doi.org/10.1107/s1600576715024620 |
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