A systematic test methodology for identifying defect-related failure mechanisms in an EEPROM technology

摘要

A new test methodology is described for identifying defect-related failures of EEPROM memory cells. Currently, tunnel oxide Qbd tests are widely used to monitor the quality of the tunnel dielectric. These Qbd tests, however, cannot provide information on the defect-driven failure mechanisms that may limit manufacturing yield. A systematic sequence of tests is described that can be used to determine if there is a single defective cell present within a large test array of EEPROM cells, and to identify the nature of the defect. The test sequence is suitable for inclusion as part of the automated Electrical Test (ET) used in the manufacture of EEPROM or Flash EEPROM memories.