Through-Lens Fiducial Marking System

Infrared emission microscope (IREM) systems are used to image active integrated circuits to analyze circuit function or locate manufacturing and design defects. IREM systems are able to directly image the operation of individual transistors or transistor groups that form logic gates. Depending on lenses used, an IREM system can resolve features smaller than 100 nm. Once an area of interest (AOI) is located on the IREM system, the test specimen is frequently moved to other workstations to perform additional processing or analysis. For example, subsequent steps may include focused ion beam (FIB) sectioning of the device or electron microscopy. When available, computer-aided design (CAD) data can be overlaid on the device image to allow the previously identified AOI to be accurately revisited and aligned on other workstations, but when CAD is not available, an innovative method for physically marking the AOI on the IREM system needs to be available. One possible method is etching microscopic fiducial marks into the silicon using a focused laser marking system integrated into the IREM.