Perfect TEM Membranes by focused ion beams: A stress reduction technique

Abstract

With the realisation that the critical dimensions in integrated circuits are shrinking to the point where scanning electron microscopy (SEM) techniques are not sufficiently accurate for many applications, advanced semiconductor fabs are looking to the increased resolution and analytical functionality of transmission electron microscopy (TEM) in failure and process analysis. TEM sample preparation is traditionally labour-intensive and needs skilled technical support but, with the acceptance of focused ion beam (FIB) workstations, this preparation and subsequent analysis is now becoming more routine. The reasons are: more reliable preparation with less risk of catastrophic breaking on unique specimens, highly site-specific preparation capable of viewing individual, sub-100 nm features, thin and uniform membranes even with tungsten plugs, and fast and easy preparation techniques.The initial stages of sample preparation involves preparing a sub-100 um sliver mounted on a TEM grid. When mounting this sliver on the grid, care must be taken to prevent any strain from being transferred to the silicon.