Curtaining Effect in FIB-EM Sample Preparation
- Practical Electron Microscopy and Database -
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This book (Practical Electron Microscopy and Database) is a reference for TEM and SEM students, operators, engineers, technicians, managers, and researchers.



One important issue of EM specimen preparation using FIB is known as the curtaining effect. This effect presents the formation of striations across the milling face when the sample has a surface with uneven topography and structures or chemical composition [1 - 2]. This effect often gives trouble to the microelectronics industry because the device structures exist at wafer surfaces. The curtaining artifact occurs when the FIB-sputtering rates are different at different locations (e.g. a tungsten contact to silicon [4]) or voids presents within the specimen.

An immediate consequence of the curtain effect related to TEM specimen is that the specimen will no longer have a uniform thickness. To avoid this issue, bottom and side cleaning procedures had been proposed [1, 3].

To eliminate the curtaining artifacts, one can mill the sample from the sides or bottom [5,6]. On the other hand, obtaining high quality thin TEM-specimen, free from damage, requires low-kV milling. However, the curtaining artifacts can be worse at low kV if it occurs.


[1] Langford RM. 2006. Focused ion beams techniques for nanomaterials characterization. Microsc Res Tech 69:538–549.
[2] Ishitani T, Umemura K, Ohnishi T, Yaguchi T, Kamino T. 2004. Improvements in performance of focused ion beam cross sectioning:
aspects of ion-sample interaction. J Electron Microsc 53:443–449.
[3] Wang Z, Kato T, Hirayama T, Kato N, Sasaki K, Saka H. 2005. Surface damage induced by focused-ion-beam milling in a Si/Si p-n junction cross-sectional specimen. Appl Surf Sci 241:80–86.
[4] Introduction to Focused Ion Beams, eds. L.A. Giannuzzi and F.A. Stevie, Springer (2005).
[5] Eduardo Montoya et al. Microscopy Research and Technique 6 (2007) 70 1060.
[6] Stephen M. Schwarz1 et al., Microsc. Microanal. 9 (Suppl. 2) (2003) 116.



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