In-Situ Quantification of TEM Lamella Thickness and Ga Implantation in the FIB

Focused Ion beam (FIB) based tools have become the preferred method to prepare TEM lamellas, largely due to their high resolution imaging capabilities used to identify the site of interest. The quality and thickness of samples has become paramount in order to take full advantage of the ever increasing resolution in aberration corrected TEMs and accurately controlling the lamella thickness at the same time as minimising any amorphisation caused by ion implantation is challenging. For instruments combining a focused ion beam with an electron beam methods based on either back scattered electron contrast [1] or transmissivity of electrons [2] have been demonstrated. However, these methods only work on homogenous samples without compositional variations and require for the contrast to be calibrated using the same material. They also don’t provide any information on ion implantation or surface amorphisation and can greatly affect the quality of the TEM image obtainable from the lamella.