R. E. Stallcup, DCG Systems, Inc., Richardson, TX; G. Nagatani, Spansion, Sunnyvale, CA

Summary: This paper covers methods used to isolate single leaky junctions in a test structure designed for Flash memory technology development. This junction leakage test structure monitors on the order of thousands of junctions that are tied together in a large grid/array. The end-of-line Wafer Electrical Test (WET) identified a population of test sites with high leakage. These high leakage sites exhibited micro-amps of current while nominal sites reported 10’s of nano-amps of current. It may be possible to isolate this failure through a repetition of micro probing or a combination of electrical testing and physical structure modification by FIB, but at the expense of spending numerous days. It will be shown that a combination of Emission Microscopy (EMMI), Electron Beam Induced Current (EBIC) characterization and an SEM nano probing can drastically simplify the fault isolation process. Results of nano probing will also be shown to prove the level of leakage detected in the faulty junction.