US 2018/0026179 A1 · Fully Compensated Synthetic Ferromagnet for Spintronics Applications

Abstract

A laminated seed layer stack with a smooth top surface having a peak to peak roughness of 0.5 nm is formed by sequentially sputter depositing a first seed layer, a first amorphous layer, a second seed layer, and a second amorphous layer where each seed layer may be Mg and has a resputtering rate 2 to 30× that of the amorphous layers that are TaN, SiN, or a CoFeM alloy. A template layer that is NiCr or NiFeCr is formed on the second amorphous layer. As a result, perpendicular magnetic anisotropy in an overlying magnetic layer that is a reference layer, free layer, or dipole layer is substantially maintained during high temperature processing up to 400° C. and is advantageous for magnetic tunnel junctions in embedded MRAMs, spintronic devices, or in read head sensors. The laminated seed layer stack may include a bottommost Ta or TaN buffer layer.

Claims26

Dependent claims

A multilayer structure for reducing film roughness in a magnetic device, comprising:

(a) a first layer made of a material with a first bond energy, and having a first surface with an “as deposited” first peak to peak roughness;
(b) a second layer that is non-crystalline or nano-crystalline and is made of a material with a second bond energy that is greater than the first bond energy such that deposition of the second layer on the first layer results in resputtering of the first layer to give a first layer with a second surface having a second peak to peak roughness substantially less than the “as deposited” first peak to peak roughness, and the second layer formed on the second surface, the second layer has a third surface with the second peak to peak roughness;
(c) a third layer made of a material with the first bond energy formed on the third surface of the second layer;
and
(d) a fourth layer that is non-crystalline or nano-crystalline with the second bond energy, and formed on a top surface of the third layer.

2 more elements

A magnetic tunnel junction (MTJ), comprising:

(a) a first seed layer (SL1) stack, comprising:
(1) a first smoothing layer formed on a substrate, the first smoothing layer comprises a lower first layer with a first resputtering rate, and an upper second layer that is non-crystalline or nano-crystalline and has a second resputtering rate wherein the first resputtering rate is about 2 to 30 times greater than the second resputtering rate;
and
(2) a first template layer formed on a top surface of the upper second layer and with a top surface having a peak to peak roughness of about 0.5 nm, the first template layer has a (111) crystal orientation to promote PMA in an overlying magnetic layer;
(b) a reference layer (RL) formed on the first template layer;
(c) a tunnel barrier layer formed on the RL;
(d) a free layer (FL) on the tunnel barrier layer;
(e) a non-magnetic spacer formed on the FL;
(f) a second seed layer stack (SL2) on the non-magnetic spacer, comprising:
(1) a second smoothing layer formed on the non-magnetic spacer, the second smoothing layer comprises a lower third layer with a third resputtering rate, and an upper fourth layer that is non-crystalline or nano-crystalline and has a fourth resputtering rate wherein the third resputtering rate is about 2 to 30 times greater than the fourth resputtering rate;
and
(2) a second template layer formed on a top surface of the upper fourth layer and with a top surface having a peak to peak roughness of about 0.5 nm;
(g) a dipole layer formed on the second template layer;
and
(h) an uppermost capping layer.

12 more elements

Dependencies are inferred from the claim text.

Fully Compensated Synthetic Ferromagnet for Spintronics Applications

Life of this patent

Fully Compensated Synthetic Ferromagnet for Spintronics Applications

Life of this patent

Abstract

Claims26