Magnetic Memory Device

• US 20100181633A1
• Filed: 01/12/2010
• Published: 07/22/2010
• Est. Priority Date: 01/21/2009
• Status: Active Grant

• Current Assignee: Samsung Electronics Co. Ltd.
• Original Assignee: Samsung Electronics Co. Ltd.
• Inventors: Oh, Sechung, Lee, Jangeun, Choi, Sukhun, Jeong, Junho, Nam, Kyungtae
• Granted Patent: US 8,129,806 B2
• Time in Patent Office: Days
• US Class Current: 257/421
• CPC Class Codes: B82Y 25/00 Nanomagnetism, e.g. magnetoimpedance, anisotropic magnetoresistance, giant magnetoresistance or tunneling magnetoresistance
• CPC Class Codes: G11C 11/161 details concerning the memory cell structure, e.g. the layers of the ferromagnetic memory cell
• CPC Class Codes: G11C 11/1675 Writing or programming circuits or methods
• CPC Class Codes: H01F 10/3254 the spacer being semiconducting or insulating, e.g. for spin tunnel junction [STJ]
• CPC Class Codes: H01F 10/3268 the exchange coupling being asymmetric, e.g. by use of additional pinning, by using antiferromagnetic or ferromagnetic coupling interface, i.e. so-called spin-valve [SV] structure, e.g. NiFe/Cu/NiFe/FeMn
• CPC Class Codes: H10B 61/22 of the field-effect transistor [FET] type
• CPC Class Codes: H10N 50/10 Magnetoresistive devices

Abstract

A magnetic memory device includes a magnetic tunnel junction (MTJ) structure and an electrode embedded in a dielectric structure. The MTJ structure includes a free layer. The electrode is formed of silicon-germanium and is electrically connected to the MTJ. The electrode heats the free layer to reduce the coercive force of the free layer to reduce a critical current density.

Claims

1. A magnetic memory device comprising:

a magnetic tunnel junction (MTJ) structure including a free layer on a semiconductor substrate; and

an electrode formed of silicon-germanium on the semiconductor substrate,

wherein the electrode heats the free layer to reduce a coercive force of the free layer for reducing a critical current density.

2. The magnetic memory device of claim 1, wherein the germanium content of the silicon-germanium is about 10% to about 57%.

3. The magnetic memory device of claim 1, wherein the silicon-germanium has a polycrystalline structure.

4. The magnetic memory device of claim 1, wherein the electrode is a top electrode disposed on the MTJ structure.

5. The magnetic memory device of claim 4, wherein the top electrode directly contacts the free layer.

6. The magnetic memory device of claim 4, wherein the MTJ structure further includes a pin layer disposed on the semiconductor substrate and a tunnel insulating layer disposed between the pin layer and the free layer,

wherein the top electrode has the same horizontal area as the free layer and has a smaller horizontal area than the pin layer and the tunnel insulating layer.

7. The magnetic memory device of claim 1, further comprising a conductive capping layer disposed between the electrode and the free layer.

8. The magnetic memory device of claim 1, further comprising a transistor supplying a current for switching a magnetization direction of the free layer.

9. The magnetic memory device of claim 1, wherein the electrode is a bottom electrode disposed between the semiconductor substrate and the MTJ structure.

10. The magnetic memory device of claim 9, wherein the bottom electrode has a smaller horizontal area than the free layer.