J. J. Demarest, K. Chanda, S. Klepeis, B. Redder, A. Shore, IBM, Hopewell Junction, NY; C. Christiansen, IBM, Essex Junction, VT; Y. Wang, Ohio State University, Columbus, OH; C. Rue, FEI Company, Hillsboro, OR

Summary: With shrinking defect size and evolving dielectric materials surrounding the metallization placed on today’s state-of-the-art computer chips, failure analysts occasionally find themselves faced with the task of identifying defects which are effectively rendered invisible to the human eye. The physics of the various isolation techniques which are available clearly indicate the presence of a defect within a certain region. However, inspection of that area with conventional techniques such as secondary electron and back scattered electron (BSE) scanning electron microscopy (SEM) does not lead to physical defects being readily apparent in the images obtained. Exploitation of subtle variations in intensity through intensity profiling can localize defects which would otherwise not be observed by comparison to healthy reference structures in adjacent locations on the sample. Both resistive shorts and resistive opens will be discussed through illustrative case studies demonstrating this technique at the 130 nm and 65 nm technology nodes in low-k dielectric materials.