Decomposition of Vertical and Lateral Charge Loss in Long-term Retention of 3-D NAND Flash Memory

Abstract

For long-term retention characteristics of 3-D NAND flash memory, a method is proposed to decompose the measured <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$\boldsymbol{V_{T}}$</tex> shift into several charge loss mechanisms, including lateral migration (LM), band-to-trap tunneling (BT), trap-to-band tunneling (TB), and thermal emission (TE). Based on the <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$\Delta \boldsymbol{V_{T}}$</tex> of the E-E-E pattern (EEE) at room temperature, the LM mechanisms of the P-E-P pattern (PEP) at high temperature (120 °C) are separated into the LM caused by hole (LMH) and electron (LME), respectively. Finally, the E-P-E pattern (EPE) and PEP are successfully decomposed into LMH, LME, TE, BT, and TB of trapped charges in the nitride layer. The proposed methodology is promising to quantitatively evaluate the charge loss mechanism in 3-D NAND flash memory.