Conductive AFM in SEM for 7 nm and beyond : AM: Advanced Metrology

Abstract

Measuring surface conduction points is a well-established analytical technique in SRAM failure analysis. A novel workflow and system have been developed that makes use of an Atomic Force Microscope (AFM) inside a Scanning Electron Microscope (SEM) and is capable of using standard laser deflection based probe tips. New results are provided on an 8T SRAM cell in 7 nm technology which demonstrate the ability to measure nFET, pFET, and gate contacts simultaneously with one scan, and with a topography measurement. A second analysis was performed to demonstrate the ability of the electron beam, combined with use of the AFM diamond tip as a scalpel, to expose subsurface layers and greatly improve current data. Furthermore, the system being in vacuum provides additional benefits in eliminating confounding effects.