Application study of simply and low cost numerical aperture increasing lens (NAIL) system for OBIRCH and EMMI in backside failure analysis

Now it was very difficult to do failure analysis (FA) from front side with multi-metal layers and scaling down. So, OBIRCH & EMMI analysis from backside was studied in microelectronics yield in recent years. As is known to all, we could capture clearer infrared (IR) image from backside as Si substrate was thinner. But if we needed higher resolution image with conventional optical objective lens, we must introduce numerical aperture increasing lens (NAIL) technology or shorter wavelength light to improve numerical aperture (NA) in objective space. The numerical aperture increasing lens (NAIL) was one effective solution for FA from backside. Many company and research center developed NAIL system which was applied in FA. In this paper, we introduce simple & low cost NAIL system to complete application study for OBIRCH and EMMI analysis. In real cases hotspots and emission spots were captured with the NAIL system from backside. As a result we obtained higher resolution image and distinguished some spots from adjacent small devices. Thus, we believed our NAIL system was beneficial to our FA from backside.