Comparing Behaviors of FIB Toolsets in a Large Scale Automated XTEM Sample Preparation Setup

Abstract Moore’s law has been a major driving force in the development of novel semiconductor devices and has continued to hold its relevance over the years. The resultant, smaller and more powerful, microprocessors not only cater to the ever-increasing demands of the existing needs but also are important enablers of novel applications and discoveries in different areas. Several critical features of these latest devices are in the atomic to nanometer scale, which has enhanced the necessity of a largescale transmission electron microscopy (TEM) imaging-based metrology and failure analysis for their process development. As a result, the automation of lamella preparation using focused ion beam (FIB) and TEM imaging has gathered an enormous momentum in last few years. A key aspect of automating a large-scale TEM sample preparation not only involves the calibration of a given FIB tool to achieve an acceptable and repeatable quality of TEM samples but also to ensure that sample quality is consistent across the entire fleet of toolsets. In this work, the performance of three ThermoFisher Exsolve toolsets using a common tool calibration method for both, lamella thickness and targeting, has been compared. It was found that in general, thickness of TEM lamella showed a larger variation as compared to targeting over the period of one month. Lamella thickness showed a decreasing trend, and it entailed a need of recalibrating the tools in an interval of two weeks so that the variation in both thickness and targeting for the fleet can be kept within the desired specifications of ±3 nm (2σ).