ELECTROCHEMICAL WET ETCHING m KOH:H2O SOLUTION AND SECONDARY/ION IMAGE PASSIVE VOLTAGE CONTRAST AS A COMPLEMENTARY TECHNIQUE IN FAILURE ANALYSIS

摘要

It is always a challenge for failure analysis engineer to localize leaky polysilicon gate. One of the common method is to use Passive Voltage Contrast (PVC). If the leakage is low and falls below 1uA (<1uA), it may be difficult to show the contrast between good and bad polysilicon gate using PVC. In this paper, techniques such as secondary/ion image PVC from Scanning Electron Microscope (SEM) / Focus Ion Beam (FIB) and electrochemical wet etching in KOH:H_2O solution are used to detect the leaky polysilicon gate. The latter is used specially for Physical detection, thus enhancing the confidence level of analysis. Both techniques will be used in complimentary manner as a failure analysis tool to detect leaky polysilicon gate.