Abstract
Precise fail site isolation plays a very important role today in the world of semiconductors. Its importance increases more, as the devices are of cutting edge technology with increasing complexity and decreasing dimensions. Global fail site isolations techniques (like XIVA, Photo Emission, FMI etc) and tester based techniques (using automatic test equipment, Fastscan etc) alone, are no longer sufficient and may not be successful. Long net lists and large fail sites isolated by these methods pose problems for physical failure analysis. Planarity of these large areas during parallel lap and inspection times using the SEM is difficult and tedious, thus leading to long cycle times and low resolution rates. There exists a need for precise fail site isolation. In many cases, no single technique can be used to narrow down a fail site significantly. Instead a combination of different techniques must be used. In this paper we present a case study, where a combination of complimentary techniques are used to successfully isolate a fail area of more than 1300 microns in length to less than 100 microns on a single failing net.
