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We present a detailed analysis of the time dynamics of the down-coupling phenomenon (DCP) in 3-D NAND Flash memory strings. The transient time dynamics of the channel potential following the wordline (WL) bias transition from the pass voltage to zero is studied via numerical simulation, highlighting the existence of three temporal regimes controlled by different physical processes: electron emission from traps, hole injection from the string edges followed by capture, and propagation along the string. The impact of these processes is separately studied, followed by an analysis of the dependence of the DCP recovery time on architectural parameters. Results highlight the relevant physics and can be used as a design guideline for NAND strings with reduced sensitivity to the DCP. Index Terms-3-D NAND Flash memories, down-coupling phenomenon (DCP), gate-induced drain leakage (GIDL) current, macaroni MOSFET, self-boosting effect. I. INTRODUCTIONT HE transition from planar to 3-D NAND Flash memories has allowed the pursuit of astonishing results in terms of density and cost [1], stacking more than 170 memory layers and overcoming the 10-Gb/mm 2 density figure [2], [3]. To continue along this path, however, an ever-increasing number of challenges from the process, design, and system viewpoints must be overcome [4], on top of which we must also account for reliability. From this standpoint, the peculiar architecture of 3-D NAND has brought to the forefront new concerns that add to the well-known problems inherited from planar arrays [5]. Examples of such new issues include phenomena related to the polycrystalline nature of the conduction channel [6], [7], [8],[9], [10], [11] and issues connected to floating-body effects in the vertical string channels.The down-coupling phenomenon (DCP) is one of the latter. Reported for the first time in 2016 [12], it describes the sudden drop in the channel potential V ch of the string that can result following a wordline (WL) step from the pass Manuscript

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