Probability Level Dependence of Failure Mechanisms in Sub-20 nm NAND Flash Memory

Abstract

We extracted final ΔV <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">th</sub> , time constant, and activation energy (E <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">a</sub> ) of each mechanism in retention characteristics of sub-20-nm NAND flash main-chip according to the probability level (P level) of V <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">th</sub> cumulative probability distribution. As a result, we confirmed that at lower P level, the final ΔV <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">th</sub> of each mechanism increases sensitively according to P/E cycling stress. Temperature dependence of the final ΔV <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">th</sub> of each mechanism also increases with lowering P level, whereas trap-assisted tunneling (TAT) mechanism of corner area has complex characteristics on temperature. Interface trap recovery, TAT (plane), and TAT (corner) mechanism have larger E <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">a</sub> at high P level, whereas the E <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">a</sub> of detrapping mechanism decreases because of barrier lowering effect.