Investigation of Retention Noise for 3-D TLC NAND Flash Memory

Abstract

In this paper, the retention noise [electron emission statistics (EES)] after program operation of 3-D triple-level program cell (TLC) NAND flash memory is investigated. Three main noise sources, consisting of essential EES (EEES), electron numbers fluctuation, and device parameters fluctuation to broaden the retention V th distributions are comprehensively considered, and the corresponding analytic models are developed. The impact of device parameters fluctuation is relatively larger than EEES and electron numbers fluctuation for our measured 3-D TLC NAND flash memory devices. Using the proposed models, the calculated V th distributions after different data retention times have good agreements with the measurements, which validate our proposed models. This paper provides a method to predict the V th distributions accurately and efficiently, and can help in improving reliability of 3-D TLC and quad-level program cell NAND flash memory. INDEX TERMS Retention V th distribution, retention noise, 3-D TLC NAND flash memory, reliability.