Ion-Beam-Etched Profile Control of MTJ Cells for Improving the Switching Characteristics of High-Density MRAM

Author

Takahashi, Shigeki ; Kai, Tadashi ; Shimomura, Naoharu ; Ueda, Tomomasa ; Amano, Minoru ; Yoshikawa, Masatoshi ; Kitagawa, Eiji ; Asao, Yoshiaki ; Ikegawa, Sumio ; Kishi, Tatsuya ; Yoda, Hiroaki ; Nagahara, Kiyokazu ; Mukai, Tomonori ; Hada, Hiromitsu

Author_Institution

Corp. Res. Dev. Center, Toshiba Corp., Kawasaki

Volume

42

Issue

10

fYear

2006

Firstpage

2745

Lastpage

2747

Abstract

The effect of the reduction of the sidewall redeposition layer of magnetic materials is investigated for submicron-patterned magnetic random access memory (MRAM) cells. The sidewall redeposition layer is made at the first etch step of a magnetic tunnel junction (MTJ) with ion beam etching (IBE) in the case that the sidewall angle of a hard mask is steep. By controlling the etched profile at the time of the first IBE step, formation of the redeposition layer is prevented. Functional test results of 1-Kb MRAM arrays show that the sidewall redeposition layer enlarges fluctuation of switching current, and reduces the write operation region. The effect of the sidewall redeposition on the switching characteristics of MRAM arrays is explained qualitatively by micromagnetic simulation solving the Landau-Lifshitz-Gilbert (LLG) equation

Keywords

etching; ion beam assisted deposition; magnetic storage; magnetic switching; magnetic tunnelling; random-access storage; Landau-Lifshitz-Gilbert equation; ion beam etching; magnetic materials; magnetic random access memory; magnetic tunnel junction cell; micromagnetic simulation; sidewall redeposition layer; switching current; Equations; Etching; Fluctuations; Identity-based encryption; Ion beams; Magnetic materials; Magnetic tunneling; Micromagnetics; Random access memory; Testing; Ion beam etching (IBE); magnetic random access memory (MRAM); magnetic tunnel junction (MTJ);

fLanguage

English

Journal_Title

Magnetics, IEEE Transactions on

Publisher

ieee

ISSN

0018-9464

Type

jour

DOI

10.1109/TMAG.2006.878862

Filename

1704425