Patent Application

App. No. 11/839,044

Abstract

Claims (34)

1 . A synthetic anti-ferromagnet (SAF) structure comprising:

a bottom ferromagnetic layer;

a coupling layer formed over the bottom ferromagnetic layer; and

a top ferromagnetic layer formed over the coupling layer;

wherein at least one of the top and bottom ferromagnetic layers comprises an amorphous CoFeB alloy characterized by (Co 100-a Fe a ) 100-z B z , where a is less than approximately 10 atomic percent, and z is greater than approximately 20 atomic percent.

2 . The SAF structure of claim 1 , wherein z is between approximately 23 and 30 atomic percent.

3 . The SAF structure of claim 1 , wherein the SAF structure is configured to provide a uniaxial anisotropy such that the kink field H k of the bottom and top ferromagnetic layers is less than approximately 16 Oe.

4 . The SAF structure of claim 1 , wherein the bottom and top ferromagnetic layers exhibit a magnetostriction λ, where λ is in the range of −1×10 −6 <λ<1×10 −6 .

5 . The structure of claim 1 , wherein the bottom ferromagnetic layer has a thickness greater than approximately 20 Å, and the second ferromagnetic layer has a thickness greater than approximately 20 Å.

6 . The structure of claim 1 , wherein the coupling layer is ruthenium.

7 . A magnetic tunnel junction (MTJ) structure comprising:

a first electrode;

a pinned synthetic anti-ferromagnet (SAF) formed over the first electrode;

a free-layer SAF formed over the pinned SAF;

a dielectric layer formed between the free-layer SAF and the pinned SAF;

a top electrode formed over the free-layer SAF;

wherein the free-layer SAF comprises a bottom ferromagnetic layer, a coupling layer formed over the bottom ferromagnetic layer, and a top ferromagnetic layer formed over the coupling layer, wherein at least one of the top and bottom ferromagnetic layers comprises an amorphous CoFeB alloy characterized by (Co 100-a Fe a ) 100-z B z , where a is less than approximately 10 atomic percent, and z is greater than approximately 20 atomic percent.

8 . The MTJ structure of claim 7 , wherein z is between approximately 23 and 30 atomic percent.

9 . The MTJ structure of claim 7 , wherein the free-layer SAF is configured to provide a uniaxial anisotropy such that a kink field H k of the top and bottom ferromagnetic layers is less than approximately 16 Oe.

10 . The MTJ structure of claim 7 , wherein the bottom and top ferromagnetic layers exhibit a magnetostriction λ, where λ is in the rang of −1×10 −6 <λ<1×10 −6 .

11 . The MTJ structure of claim 7 , wherein the bottom ferromagnetic layer has a thickness greater than approximately 20 Å, and the second ferromagnetic layer has a thickness greater than approximately 20 Å.

12 . The MTJ structure of claim 7 , wherein the coupling layer is ruthenium.

13 . A method of fabricating a synthetic antiferromagnet (SAF) comprising:

forming a bottom ferromagnetic layer;

forming a coupling layer over the bottom ferromagnetic layer; and

forming a top ferromagnetic layer over the coupling layer;

wherein forming the top and bottom ferromagnetic layers includes forming an amorphous CoFeB alloy characterized by (Co 100-a Fe a ) 100-z B z , where a is less than approximately 10 atomic percent, and z is greater than approximately 20 atomic percent.

14 . The method of claim 13 , wherein z is between approximately 23 and 30 atomic percent.

15 . The method of claim 13 , wherein the SAF structure is configured to provide a uniaxial anisotropy such that a kink field H k of the bottom and top ferromagnetic layers is less than approximately 16 Oe.

16 . The method of claim 13 , wherein the ferromagnetic layers exhibit a magnetostriction λ, where λ is in the rang of −1×10 −6 <λ<1×10 −6 .

17 . The method of claim 13 , wherein forming the bottom ferromagnetic layer includes forming a layer having a thickness greater than approximately 20 Å, and forming the top ferromagnetic layer includes forming a layer having a thickness greater than approximately 20 Å.

18 . The method of claim 13 , wherein forming the bottom and top ferromagnetic layers includes co-sputtering films at least two different targets.

19 . The method of claim 13 , wherein forming the bottom and top ferromagnetic layers includes multilayering films using sputtering deposition.

20 . A magnetic device with at least one magnetic layer comprising an amorphous CoFeB alloy characterized by (Co 100-a Fe a ) 100-z B z , where a is less than approximately 10 atomic percent, and z is greater than approximately 20 atomic percent.

Assignments (15)