Impact of Program/Erase Cycling Interval on the Transconductance Distribution of NAND Flash Memory Devices

Autor: Kai-Chieh Chang, Masaru Yano, Yung-Yueh Chiu, Hsin-Chiao Li, Toshiaki Takeshita, Hung-Te-En Tsai, Riichiro Shirota, Hsin-Jyun Lin, Po-Jui Lin
Rok vydání: 2020
Předmět:
Zdroj: IEEE Transactions on Electron Devices. 67:4897-4903
ISSN: 1557-9646
0018-9383
DOI: 10.1109/ted.2020.3024484
Popis: This study comprehensively investigates the impact of the time interval ( ${t}_{\text {wait}}$ ) between program/erase (P/E) cycles on the oxide quality of NAND Flash memory devices. It is observed that, at room temperature, P/E cycles with a shorter ${t}_{\text {wait}}$ yield a better oxide quality than those with a longer ${t}_{\text {wait}}$ . The oxide charge ( ${Q}_{T}$ ) evolution by distributed P/E cycles can be well described by an analytical equation through the extension of our previous statistical transconductance reduction ( $\Delta {G}_{m,\text {max}}$ ) method. This equation is characterized by a power of the number of P/E cycles multiplied by an exponential decay term of ${t}_{\text {wait}}$ . The former term is related to the ${Q}_{T}$ generation, whereas the latter is related to the ${Q}_{T}$ emission during ${t}_{\text {wait}}$ between cycles. This model allows to evaluate the activation energy for both ${Q}_{T}$ generation ( ${E}_{\text {A,G}}$ ) and recovery ( ${E}_{\text {A,R}}$ ). ${E}_{\text {A,G}}$ is revealed to be a function of the logarithmic scale of $t_{\text {wait}}$ , decreasing from 100 to 85 meV for ${t}_{\text {wait}}$ varying from 0.1 to 4 s. Moreover, ${E}_{\text {A,R}}$ is approximately 0.4 eV, which is consistent with the value of electron thermal emission from traps in SiO2.
Databáze: OpenAIRE