Detection of critical defects with E-beam technology for development and monitoring of advanced NAND processes

This paper describes the technique of using electron beam inspection (EBI) for the purpose of detecting critical yield-limiting defects in the development of advanced NAND processes. Signal to noise analysis was conducted on a V1WCMP wafer of a NAND flash device to optimize e-beam conditions to obtain best sensitivity to DOI (defect of interest) detection. TEM analysis was performed to confirm detection of defects due to subtle and severe under-etch. Correlation of inspection results with split process conditions is demonstrated. Experiments were also carried out to determine the best inspection parameters to achieve highest throughput required for fast process development cycle time as well as production monitoring of advanced NAND flash memory manufacturing.