Defect Isolation of Functional Failed 3D NAND Device Memory Using Memory Tester and Test Bench with OBIRCH

Flash memory has become the most important form of digital storage due to the increased demand for memory devices. The 3D NAND structure has been invented and continuously improved over time, encompassing advancements in XY scaling, stack height scaling, and CMOS scaling from circuit-neighboring-array to circuit-under-array to Circuit Bonded Array. However, these advancements have necessitated the development of failure analysis and defect localization techniques to identify the location and mode of defects. One such technique is Optical Beam Induced Resistance Change (OBIRCH), which utilizes a laser source to induce resistance changes at the site of a defect. This non-destructive process allows for the preservation of device functionality during testing. However, due to the complexity of NAND functionality, it is challenging to detect short circuits or leakage signals that are unrelated to the supply pins. In this study, a connected probe card and memory tester were installed in the PHEMOS-1000 system to trigger functional defects of a NAND wafer. During testing, all the required signals on the wafer-form Device Under Test (DUT) were connected using a bench tester. Two failure analysis case studies were conducted successfully, resulting in the localization of device-level defects. In short, this approach enabled the identification and localization of functional failures, including erase and program failures, in 3D NAND devices by connecting to a memory tester using a bench tester and utilizing the PHEMOS-1000 OBIRCH system.