A Vertical 4-Bit SONOS Flash Memory and a Unique 3-D Vertical nor Array Structure

Author

Kim, Yoon ; Park, Il Han ; Cho, Seongjae ; Yun, Jang-Gn ; Lee, Jung Hoon ; Kim, Doo-Hyun ; Lee, Gil Sung ; Park, Se-Hwan ; Lee, Dong Hua ; Sim, Won Bo ; Kim, Wandong ; Shin, Hyungcheol ; Lee, Jong-Duk ; Park, Byung-Gook

Author_Institution

Sch. of Electr. Eng. & Comput. Sci., Seoul Nat. Univ., Seoul, South Korea

Volume

9

Issue

1

fYear

2010

Firstpage

70

Lastpage

77

Abstract

In order to overcome the limitation of a multibit silicon-oxide-nitride-oxide-silicon (SONOS) memory with multistorage nodes, we propose a unique 3-D vertical NOR (U3VNOR) array architecture. The U3VNOR has a vertical channel so that it is possible to have a long enough channel without extra cell area. Therefore, we can avoid the problems such as redistribution of injected charges, second-bit effect, and short-channel effect. Also, it is the most integrated flash architecture having the smallest unit cell size, which is 1 F²/bit. In this paper, we present the fabrication method and the operation voltage scheme of the U3VNOR. In addition, through numerical simulation, we verify its program and erase characteristics. Due to its high density and reliable multibit operation, the U3VNOR is a promising structure for the future high-density NOR flash memory.

Keywords

NOR circuits; flash memories; numerical analysis; 3-D vertical NOR array structure; SONOS flash memory; erase characteristics; high-density NOR flash memory applications; injected charge redistribution; integrated flash architecture; multibit operation; multibit silicon-oxide-nitride-oxide-silicon memory; multistorage nodes; numerical simulation; program verification; second-bit effect; short-channel effect; storage capacity 4 bit; 3-D array; flash memory; silicon–oxide–nitride–oxide–silicon (SONOS); vertical channel;

fLanguage

English

Journal_Title

Nanotechnology, IEEE Transactions on

Publisher

ieee

ISSN

1536-125X

Type

jour

DOI

10.1109/TNANO.2009.2026173

Filename

5153353