Electrical Screening Method of V-NAND Flash Channel Hole Bending Defects

This paper presents a novel approach for detecting channel hole bending (ChB) defects in vertical NAND flash memory. Such defects are the result of etching process inconsistencies and contribute to data loss and device failure by inducing leakage current between adjacent channel holes. In order to satisfy long-term reliability requirements and volume demand, chipmakers must be able to detect these defects prior to shipping during electrical die sorting and screening procedures. The proposed method works by monitoring leakage current differences between diagonally and horizontally adjacent memory cells and is shown to be an effective screening technique.