Sidewall damage induced by FIB milling during TEM sample preparation

A novel method was brought out to observe the physical thickness of crystal damage layer on sidewall of TEM sample. The physical thickness of the damaged layer at different accelerated voltage and beam current was given. The damage depth is about 23 and 11 nanometer at 30KeV and 10KeV ion beam, respectively. For the current, damage layer thickness keeps constant with different beam current range from 30pA to 1000pA. According to our experiment result the amorphous layer thickness keeps constant in despite of the sample tilt angle. The angle between incident beam and sample sidewall keeps fixed independent of the sample tilt. The taper of the sample will vary with different tilt angle and then the ratio between crystal and whole sample decreases with the increase of tilt angle, especially when the tilt angle exceeds 2°.