SPRAM with large thermal stability for high immunity to read disturbance and long retention for high-temperature operation

Author

Ono, K. ; Kawahara, T. ; Takemura, R. ; Miura, K. ; Yamanouchi, M. ; Hayakawa, J. ; Ito, K. ; Takahashi, H. ; Matsuoka, H. ; Ikeda, S. ; Ohno, H.

Author_Institution

Central Res. Lab., Hitachi, Ltd., Kokubunji, Japan

fYear

2009

fDate

16-18 June 2009

Firstpage

228

Lastpage

229

Abstract

We investigate the effect of temperature on current-induced magnetization switching in SPRAM (spin-transfer torque RAM) consisting of MgO-barrier-based magnetic tunnel junctions (MTJs) with a synthetic ferrimagnetic recording layer (SyF) by comparing the MJTs to those with a single ferromagnetic recording layer. It is found that SPRAM using MTJs with a SyF has two advantages for high-temperature operation: 1) A thermal stability factor E/k_BT as high as 64 at 150degC, which would ensure ten-year retention and ten-year immunity to read disturbance; and 2) an increase of the aspect ratio in the SyF, which leads to high coercivity H_C, resulting in two stable states (ldquo0rdquo or ldquo1rdquo) at high temperature.

Keywords

magnesium compounds; magnetic tunnelling; random-access storage; thermal stability; MgO; SPRAM; aspect ratio; barrier-based magnetic tunnel junction; current-induced magnetization switching; single ferromagnetic recording layer; spin-transfer torque RAM; synthetic ferrimagnetic recording layer; temperature 150 degC; temperature effect; thermal stability factor; Coercive force; Ferrimagnetic materials; Magnetic recording; Magnetic switching; Magnetic tunneling; Magnetization; Temperature; Thermal factors; Thermal stability; Torque;

fLanguage

English

Publisher

ieee

Conference_Titel

VLSI Technology, 2009 Symposium on

Conference_Location

Honolulu, HI

Print_ISBN

978-1-4244-3308-7

Type

conf

Filename

5200609