# US 2013/0154038 A1 · High Performance MTJ Element for Conventional MRAM and for STT-RAM and a Method for Making the Same

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- Number: US 2013/0154038 A1
- Document ID: US20130154038A1
- Status: Published application
- Kind: A1
- Application number: 13/764,357
- Filed: 2013-02-11
- Published: 2013-06-20
- Earliest claimed: 2007-10-31
- Assignees: MagIC Technologies, Inc.
- Inventors: Cheng T. Horng; Ru-Ying Tong; Chyu-Jiuh Torng; Witold Kula
- Web page: https://patentgrep.com/patent/US20130154038A1

## CPC

- H10N 50/85: Materials of the active region
- B82Y 10/00: Nanotechnology for information processing, storage or transmission, e.g. quantum computing or single electron logic
- H10N 50/01: Manufacture or treatment
- H10N 50/10: Magnetoresistive devices
- H10B 61/22: {of the field-effect transistor [FET] type}
- H10N: ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
- B82Y: SPECIFIC USES OR APPLICATIONS OF NANOSTRUCTURES; MEASUREMENT OR ANALYSIS OF NANOSTRUCTURES; MANUFACTURE OR TREATMENT OF NANOSTRUCTURES
- H10B: ELECTRONIC MEMORY DEVICES

## Abstract

A STT-RAM MTJ that minimizes spin-transfer magnetization switching current (Jc) is disclosed. The MTJ has a MgO tunnel barrier layer formed with a natural oxidation process to achieve a low RA (10 ohm-um2) and a Fe or Fe/CoFeB/Fe free layer which provides a lower intrinsic damping constant than a CoFeB free layer. A Fe, FeB, or Fe/CoFeB/Fe free layer when formed with a MgO tunnel barrier (radical oxidation process) and a CoFeB AP1 pinned layer in a MRAM MTJ stack annealed at 360° C. provides a high dR/R (TMR)>100% and a substantial improvement in read margin with a TMR/Rp_cov=20. High speed measurement of 100 nm×200 nm oval STT-RAM MTJs has shown a Jc0 for switching a Fe free layer is one half that for switching an amorphous Co40Fe40B20 free layer. A Fe/CoFeB/Fe free layer configuration allows the Hc value to be increased for STT-RAM applications.

## Claims

### Claim 1

A MTJ element comprised of a stack of layers formed on a substrate in a memory device, comprising:
(a) a synthetic anti-ferromagnetic (SyAF) pinned layer having an AP2/coupling layer/AP1 configuration such that a magnetic moment of the AP2 layer is anti-parallel to a magnetic moment in the AP1 layer, the AP2 layer is formed on an anti-ferromagnetic (AFM) layer and the AP1 layer contacts a bottom surface of a tunnel barrier layer;
(b) a crystalline MgO tunnel barrier layer that contacts the AP1 pinned layer; and
(c) a free layer made of Fe, FeB, or Fe/CoFeB/Fe formed on a top surface of the MgO tunnel barrier.

### Claim 2 (depends on 1)

The MTJ element of claim 1 wherein the AFM layer is made of MnPt and said MTJ element is further comprised of a NiCr seed layer formed between the substrate and the AFM layer, and a Ta, Ta/Ru, or NiFeHf/Ta/Ru capping layer formed on the free layer.

### Claim 3 (depends on 1)

The MTJ element of claim 1 wherein the free layer is Fe and has a thickness from about 21 to 25 Angstroms.

### Claim 4 (depends on 1)

The MTJ element of claim 1 wherein the free layer has a Fe/CoFeB/Fe configuration and the lower Fe layer on the MgO tunnel barrier has a thickness from about 3 to 5 Angstroms, the CoFeB layer has a thickness of about 10 to 12 Angstroms, and the upper Fe layer has a thickness from about 5 to 6 Angstroms.

### Claim 5 (depends on 2)

The MTJ element of claim 2 wherein the memory device is a MRAM, the AP2 layer is comprised of CoFe, and the AP1 layer is made of CoFeB.

### Claim 6 (depends on 2)

The MTJ element of claim 2 wherein the memory device is a STT-RAM, the AP2 layer is comprised of CoFe, and the AP1 layer is comprised of CoFeB.

### Claim 7 (depends on 1)

The MTJ element of claim 1 wherein the free layer is FeB and has a B content between 0 and 5 atomic %.

### Claim 8 (depends on 3)

The MTJ element of claim 3 wherein both of the Fe layer and MgO tunnel barrier layer have a (001) crystal orientation.