Practical Electron Microscopy and Database

Based on the theory of ion channeling effect, certain orientations, typically those with low index directions aligned parallel to the ion beam direction, will allow the ions to penetrate more deeply because these crystal orientations allow the ions to travel with a lower probability of collision with the atoms in the substrate. As a result, the sputter yield from grains in channeling orientations is lower than for randomly orientated grains [1 - 4].

[1] Kempshaw, B.W., Schwarz, S.M., Prenitzer, B.I. & Giannuzzi, L.A. (2001). Ion channeling effects on the focused ion beam milling of Cu. J Vac Sci Technol B 19, 749–754.
[2] Casey, J.D., Phaneuf, M.W., Chandler, C., Megorden, M., Noll, K.E., Schuman, R.J., Krechmer, A., Monforte, D., Antonniou, N., Bassom, N., Li, J., Carleson, P. & Huynh,
C.J. (2002). Copper device editing: Strategy for focused ion beam milling of copper. Vac Sci Technol B 20, 2682–2685.
[3] Adams, D.P., Vasile, M.J. & Mayer, T.M. (2006). Focused ion beam sculpting curved shape cavities in crystalline and amorphous targets. J Vac Sci Technol B 24, 1766–1775.
[4] Mulders, J.J.L., de Winter, D.A.M. & Duinkerken, W. J. H. C. P. (2007). Measurement and calculations of FIB milling yield of bulk metals. Microelec Eng 84, 1540–1543.