Defect Localization and Electrical Fault Isolation for Metal Connection Using Helium Ion Microscope

Abstract

As semiconductor process technology moves further to smaller feature sizes, novel materials and processes are introduced to increase functional device density. [1] It is challenging to have facile approaches to evaluate the new processes for metal connections, including defect localization and electrical fault isolation. Passive voltage contrast imaging is an easy way to localize defects in conductive structures. Charge accumulation with primary electron or ion beam irradiation will cause the image darkening in floating structure regions revealing defects. In general, Ga focused ion beam (Ga-FIB) and scanning electron microscope (SEM) have been used for defect localization with voltage contrast in the semiconductor industry. [2] Helium ion microscope (HIM) has been developed as light ion beam technology for many applications in imaging, nanofabrication and elemental analysis. [3] Voltage contrast images for defect localization and verification of electrical fault isolation using HIM have advantages such as lower sputtering and higher resolution compared to Ga-FIB and greater voltage contrast compared to SEM.