US2009218645A1PendingUtilityA1

multi-state spin-torque transfer magnetic random access memory

42
Assignee: YADAV TECHNOLOGY INCPriority: Feb 12, 2007Filed: Mar 3, 2009Published: Sep 3, 2009
Est. expiryFeb 12, 2027(~0.5 yrs left)· nominal 20-yr term from priority
Inventors:Rajiv Yadav RanjanParviz Keshtbod
G11C 11/5607Y10S977/933G11C 11/1675G11C 11/161G11C 2211/5615Y10S977/935G11C 11/16H10B 61/22H10N 50/80H10N 50/10
42
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Claims

Abstract

A multi-state spin-torque transfer magnetic random access memory (STTMRAM) is formed on a film and includes a first magnetic tunneling junctions (MTJ) having a first fixed layer, a first sub-magnetic tunnel junction (sub-MTJ) layer and a first free layer. The first fixed layer and first free layer each have a first magnetic anisotropy. The STTMRAM further includes a non-magnetic spacing layer formed on top of the first MTJ layer and a second MTJ formed on top of the non-magnetic spacing layer. The second MTJ has a second fixed layer, a second sub-MTJ layer and a second free layer. The second fixed and second free layers each have a second magnetic anisotropy, wherein at least one of the first or second magnetic anisotropy is perpendicular to the plane of the film.

Claims

exact text as granted — not AI-modified
1 . A multi-state spin-torque transfer magnetic random access memory (STTMRAM) formed on a film and comprising:
 a first magnetic tunneling junction (MTJ) having a first fixed layer, a first sub-magnetic tunnel junction (sub-MTJ) layer formed on top of the first fixed layer, and a first free layer formed on top of the first sub-MTJ layer, the first fixed layer and first free layer each having a first magnetic anisotropy;   non-magnetic spacing layer formed on top of the first MTJ layer; and   a second MTJ formed on top of the non-magnetic spacing layer and having a second fixed layer, a second sub-MTJ layer and a second free layer, the second sub-MTJ layer formed on top of the second fixed layer, the second free layer formed on top of the second sub-MTJ layer, the second fixed and second free layers each having a second magnetic anisotropy,   wherein at least one of the first or second magnetic anisotropy is perpendicular to the plane of the film.   
   
   
       2 . The multi-state STTMRAM, as recited in  claim 1 , further including a first cap layer formed on top of the first free layer. 
   
   
       3 . The multi-state STTMRAM, as recited in  claim 2 , further including a second cap layer formed on top of the second free layer. 
   
   
       4 . The multi-state STTMRAM, as recited in  claim 3 , further including a top electrode (TL) formed on top of the second cap layer. 
   
   
       5 . The multi-state STTMRAM, as recited in  claim 1 , wherein the first and second magnetic anisotropy are perpendicular to the plane film. 
   
   
       6 . The multi-state STTMRAM, as recited in  claim 5 , wherein the first sub-magnetic tunnel junction (sub-MTJ) layer includes a first spin polarization enhanced layer (SPEL), a first tunneling layer formed on top of the first SPEL and a second SPEL formed on top of the first tunneling layer. 
   
   
       7 . The multi-state STTMRAM, as recited in  claim 6 , wherein the second free layer is a second composite free layer. 
   
   
       8 . The multi-state STTMRAM, as recited in  claim 7 , wherein the composite free layer comprises a first sub-free layer, a nano-current channel (NCC) layer formed on top of the first sub-free layer and a second sub-free layer formed on top of the NCC layer. 
   
   
       9 . The multi-state STTMRAM, as recited in  claim 10 , wherein the second sub-magnetic tunnel junction (sub-MTJ) layer includes a third SPEL, a second tunneling layer formed on top of the third SPEL and a fourth SPEL formed on top of the second tunneling layer. 
   
   
       10 . The multi-state STTMRAM, as recited in  claim 1 , further including a bottom electrode (BE) formed on top of the film. 
   
   
       11 . The multi-state STTMRAM, as recited in  claim 10 , further including a first underlayer formed on top of the BE. 
   
   
       12 . The multi-state STTMRAM, as recited in  claim 11 , further including a first anti-ferromagnetic (AFM) formed on top of the first underlayer. 
   
   
       13 . The multi-state STTMRAM, as recited in  claim 11 , further including a second underlayer formed on top of the non-magnetic spacing layer. 
   
   
       14 . The multi-state STTMRAM, as recited in  claim 13 , further including a second AFM layer formed on top of the second underlayer. 
   
   
       15 . The multi-state STTMRAM, as recited in  claim 13 , further including a second AFM layer formed on top of the second underlayer. 
   
   
       16 . The multi-state STTMRAM of  claim 6 , wherein the first free layer is a first composite free layer. 
   
   
       17 . The multi-state STTMRAM of  claim 16 , wherein the first composite free layer comprises a first sub-free layer, a nano-current channel (NCC) layer formed on top of the first sub-free layer and a second sub-free layer formed on top of the NCC layer. 
   
   
       18 . The multi-state STTMRAM of  claim 5 , wherein the first sub-magnetic tunnel junction (sub-MTJ) layer comprises a first spin polarization enhanced layer (SPEL), a first tunneling layer formed on top of the first SPEL, and a second SPEL formed on top of the first tunneling layer. 
   
   
       19 . The multi-state STTMRAM of  claim 18 , wherein the second sub-MTJ layer comprises a third SPEL layer, a second tunneling layer formed on top of the third SPEL, and a fourth SPEL formed on top of the second tunneling layer. 
   
   
       20 . The multi-state STTMRAM of  claim 19 , wherein the second free layer formed on top of the second sub-MTJ layer is a first composite free layer. 
   
   
       21 . The multi-state STTMRAM of  claim 7 , wherein the first sub-magnetic tunnel junction (sub-MTJ) layer comprises a first spin polarization enhanced layer (SPEL), a first tunneling layer formed on top of the first SPEL, and a second SPEL formed on top of the first tunneling layer. 
   
   
       22 . The multi-state STTMRAM of  claim 21 , wherein the second sub-MTJ layer comprises a third SPEL layer, a second tunneling layer formed on top of the third SPEL, and a fourth SPEL formed on top of the second tunneling layer. 
   
   
       23 . The multi-state STTMRAM of  claim 22 , wherein the second free layer formed on top of the second sub-MTJ layer is a first composite free layer. 
   
   
       24 . The multi-state STTMRAM of  claim 12 , wherein the first sub-magnetic tunnel junction (sub-MTJ) layer comprises a first spin polarization enhanced layer (SPEL), a first tunneling layer formed on top of the first SPEL, and a second SPEL formed on top of the first tunneling layer. 
   
   
       25 . The multi-state STTMRAM of  claim 24 , wherein the second sub-MTJ layer comprises a third SPEL layer, a second tunneling layer formed on top of the third SPEL, and a fourth SPEL formed on top of the second tunneling layer. 
   
   
       26 . The multi-state STTMRAM of  claim 13 , wherein the first sub-magnetic tunnel junction (sub-MTJ) layer comprises a first spin polarization enhanced layer (SPEL), a first tunneling layer formed on top of the first SPEL, and a second SPEL formed on top of the first tunneling layer. 
   
   
       27 . The multi-state STTMRAM of  claim 26 , wherein the second sub-MTJ layer comprises a third SPEL layer, a second tunneling layer formed on top of the third SPEL, and a fourth SPEL formed on top of the second tunneling layer. 
   
   
       28 . The multi-state STTMRAM of  claim 27 , wherein the first free layer formed on top of the first sub-MTJ layer is a first composite free layer. 
   
   
       29 . The multi-state STTMRAM of  claim 28 , wherein the second free layer formed on top of the second sub-MTJ layer is a second composite free layer. 
   
   
       30 . The multi-state STTMRAM of  claim 29 , wherein the first composite free layer comprises a first sub-free layer, a nano-current channel (NCC) layer formed on top of the first sub-free layer and a second sub-free layer formed on top of the NCC layer. 
   
   
       31 . The multi-state STTMRAM of  claim 10 , wherein the first sub-magnetic tunnel junction (sub-MTJ) layer comprises a first spin polarization enhanced layer (SPEL), a first tunneling layer formed on top of the first SPEL, and a second SPEL formed on top of the first tunneling layer. 
   
   
       32 . The multi-state STTMRAM of  claim 31 , wherein the second sub-MTJ layer comprises a third SPEL layer, a second tunneling layer formed on top of the third SPEL, and a fourth SPEL formed on top of the second tunneling layer. 
   
   
       33 . The multi-state STTMRAM of  claim 32 , wherein the first free layer formed on top of the first sub-MTJ layer is a first composite free layer. 
   
   
       34 . The multi-state STTMRAM of  claim 33 , wherein the second free layer formed on top of the first sub-MTJ layer is a first composite free layer. 
   
   
       35 . The multi-state STTMRAM of  claim 34 , wherein the first composite free layer comprises a first sub-free layer, a nano-current channel (NCC) layer formed on top of the first sub-free layer and a second sub-free layer formed on top of the NCC layer. 
   
   
       36 . The multi-state STTMRAM of  claim 31 , wherein the first magnetic anisotropy is perpendicular to the plane of the film, and the second magnetic anisotropy is parallel to the plane of the film. 
   
   
       37 . The multi-state STTMRAM of  claim 22 , wherein the first magnetic anisotropy is perpendicular to the plane of the film, and the second magnetic anisotropy is parallel to the plane of the film. 
   
   
       38 . The multi-state STTMRAM of  claim 23 , wherein the first magnetic anisotropy is perpendicular to the plane of the film, and the second magnetic anisotropy is parallel to the plane of the film. 
   
   
       39 . The multi-state STTMRAM of  claim 29 , wherein the first magnetic anisotropy is parallel to the plane of the film, and the second magnetic anisotropy is perpendicular to the plane of the film. 
   
   
       40 . The multi-state STTMRAM of  claim 30 , wherein the first magnetic anisotropy is parallel to the plane of the film, and the second magnetic anisotropy is perpendicular to the plane of the film. 
   
   
       41 . The multi-state STTMRAM of  claim 32 , wherein the first magnetic anisotropy is perpendicular to the plane of the film, and the second magnetic anisotropy is parallel to the plane of the film. 
   
   
       42 . The multi-state STTMRAM of  claim 33 , wherein the first magnetic anisotropy is perpendicular to the plane of the film, and the second magnetic anisotropy is parallel to the plane of the film. 
   
   
       43 . The multi-state STTMRAM of  claim 34 , wherein the first magnetic anisotropy is perpendicular to the plane of the film, and the second magnetic anisotropy is parallel to the plane of the film. 
   
   
       44 . The multi-state STTMRAM of  claim 35 , wherein the first magnetic anisotropy is perpendicular to the plane of the film, and the second magnetic anisotropy is parallel to the plane of the film. 
   
   
       45 . The multi-state STTMRAM of  claim 17 , wherein the first magnetic anisotropy is parallel to the plane of the film, and the second magnetic anisotropy is parallel to the plane of the film. 
   
   
       46 . The multi-state STTMRAM of  claim 1 , further including more than two MTJs. 
   
   
       47 . The multi-state STTMRAM of  claim 1 , wherein the shape of the STTMRAM is circular. 
   
   
       48 . The multi-state STTMRAM of  claim 1 , wherein the shape of the STTMRAM is cylindrical. 
   
   
       49 . The multi-state STTMRAM of  claim 1 , wherein the shape of the STTMRAM is rectangular. 
   
   
       50 . The multi-state STTMRAM of  claim 1 , wherein the shape of the STTMRAM is oval.

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