Abstract
In charge-trap (CT) three-dimensional (3D) NAND flash memory, the transition layer between Si <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> N <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">4</sub> CT layer and SiO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> tunneling layer is inevitable, and the defects in the transition layer are expected to cause both lateral and vertical charge loss. Here, by first-principles calculations, we present a detailed study on the defects in the transition layer Si <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> N <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> O to comprehend their impacts on charge loss in CT 3D NAND flash memory. It is shown that shallow-trap centers, such as intrinsic nitrogen vacancy ( V <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">N</sub> ) and interstitial Ti (Ti <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">i</sub> ), can couple with the conduction band of Si <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> N <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> O to lead to lateral charge loss. On the other hand, the N substituting Si atom ( N <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">Si</sub> ) and Ti substituting Si atom (Ti <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">Si</sub> ) defects in the transition layer can couple through resonance with the trap centers in Si <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> N <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">4</sub> , leading to vertical charge loss from the CT layer to the transition layer. Our results strongly suggest that appropriate treatment of the transition layer and hydrogen passivation are both important for avoiding charge loss in CT 3D NAND flash memory.
Highlights
Ultra-high density storages are urgently needed for data storage and management at the age of big data
Our results reveal that appropriate treatment of the transition layer (Si2N2O) and hydrogen passivation are both important for improving the reliability in 3D NAND flash memory
A schematic diagram of the formation energy has been shown in Fig. 2(a), in which the electron trap level (Et, marked by filled circle) of a defect is defined as the energy difference between the conduction band minimum (CBM) and that of the transition level
Summary
Ultra-high density storages are urgently needed for data storage and management at the age of big data. 3D charge-trap (CT) NAND flash memory, which usually adopts a macaroni-like vertical channel structure, has been rapidly developed because of its ultra-high storage density, low cost, well reliability, and diversity in novel applications [3]–[8]. The cylindrical shape of 3D CT NAND with ONO stack (SiO2/Si3N4/SiO2) from inside out is beneficial to the field distribution in the CT layer (Si3N4), which allows thicker tunneling oxide (SiO2) to enlarge the memory window [9]. This well-established structure brings issues that have yet to be solved.
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
