INVESTIGATION OF SURFACE AMORPHIZATION OF SILICON-WAFERS DURING ION-MILLING

Artifacts in the preparation of samples for transmission electron microscopy (TEM) are a well known but often underestimated problem. To investigate changes in the surface structure during the final preparation step of TEM samples, the ion-etching to electron transparency, (100)-oriented Si wafers were ion-milled with Ar beams of varying energy and angle of incidence. One effect of ion-milling is the generation of an amorphous surface layer whose thickness increases with ion energy and angle of incidence. A simple model is used to compare the measured thickness of the layers with theoretical values. These were calculated from tabulated data of damage functions deduced from transport theory.