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FIB Milling of a Side Wall

Focused beams of Ga ions are routinely used to thin samples for transmission electron microscopy (TEM). This is best done at grazing incidence (ion beam almost parallel to the surface, gray area in vertical direction in the figure on the right). The original geometry is indicated by the dashed line. Under the beam the surface recedes to the right. By scanning (moving) the beam to the right at an appropriate speed the side wall can be eroded to a desired position. The W layer screens the Si substrate from the beam tails.

The image quality of TEM is affected by the contamination with Ga ions and the damage generated by the ion bombardement. The figure on the right shows the Ga concentration calculated self-consistently with surface evolution using the binary collision Monte Carlo simulator FIBSIM.