Magnetic random access memory devices having titanium-rich lower electrodes with oxide layer and oriented tunneling barrier

• US 7,352,021 B2
• Filed: 07/09/2004
• Issued: 04/01/2008
• Est. Priority Date: 07/10/2003
• Status: Expired due to Term

• Current Assignee: Samsung Electronics Co. Ltd.
• Original Assignee: Samsung Electronics Co. Ltd.
• Inventors: Ha, Young-Ki, Baek, In-Gyu, Lee, Jang-Eun, Bae, Jun-Soo, Kim, Hyun-Jo
• Primary Examiner(s): SEFER, AHMED N
• Application Number:
  US10/888,964
• Publication Number:
  US 20050006682A1
• Time in Patent Office: 1,362 Days
• Field of Search: 257/295, 438/3, 438/238
• US Class Current: 257/295
• CPC Class Codes: B82Y 10/00 Nanotechnology for information processing, storage or transmission, e.g. quantum computing or single electron logic
• CPC Class Codes: B82Y 25/00 Nanomagnetism, e.g. magnetoimpedance, anisotropic magnetoresistance, giant magnetoresistance or tunneling magnetoresistance
• CPC Class Codes: G11B 5/3909 Arrangements using a magnetic tunnel junction
• CPC Class Codes: G11C 11/16 using elements in which the storage effect is based on magnetic spin effect
• CPC Class Codes: H01F 10/3254 the spacer being semiconducting or insulating, e.g. for spin tunnel junction [STJ]
• CPC Class Codes: H01F 41/302 for applying spin-exchange-coupled multilayers, e.g. nanostructured superlattices spin-exchange-coupled multilayers H01F10/32
• CPC Class Codes: H10N 50/01 Manufacture or treatment
• CPC Class Codes: H10N 50/10 Magnetoresistive devices

Abstract

Magnetic Random Access Memory (MRAM) devices include a lower electrode and a magnetic tunnel junction on the lower electrode. The magnetic tunnel junction includes a seed layer and a tunneling barrier that is oriented in a same direction as the most closely packed plane direction of the seed layer. An oxide layer may be provided between the lower electrode and the magnetic tunnel junction. The lower electrode may be a titanium-rich TiN layer having more than 50 atomic percent titanium content. Analogous fabrication methods are also described.

Claims

1. A magnetic tunnel junction structure for a magnetic random access memory comprising:

a lower electrode that comprises a Ti-rich TiN layer having a titanium (Ti) content of between about 70 and about 90 atomic percent, the Ti-rich TiN layer having a lower chemical mechanical polishing rate than a stoichiometric TiN layer and having a surface roughness that is also lower than a stoichiometric TiN layer;

an oxide layer on the lower electrode; and

a magnetic tunnel junction on the oxide layer, the magnetic tunnel junction comprising;

a fixed layer including a seed layer;

a tunneling barrier on the seed layer, that is oriented in a same crystalline direction as a most closely packed plane direction of the seed layer, the surface roughness of the tunneling barrier being reduced by the lower surface roughness of the Ti-rich TiN layer; and

a free layer on the tunneling barrier.

2. The magnetic tunnel junction structure of claim 1, wherein the seed layer and the tunneling barrier have a same crystalline structure.

3. The magnetic tunnel junction structure of claim 2, wherein the seed layer includes tantalum (Ta), and the tunneling barrier includes oxy-aluminum (AlO_X).

4. The magnetic tunnel junction structure of claim 1, wherein the crystalline structure is a face centered cubic (FCC) structure.

5. The magnetic tunnel junction structure of claim 1, wherein the fixed layer includes a first ferromagnetic layer that comprises two ferromagnetic materials, and a non-ferromagnetic layer therebetween, and the non-ferromagnetic layer comprises at least one of Ru, Re, Rh, Cu and/or Cr.

6. The magnetic tunnel junction structure of claim 1, wherein the free layer is comprised of a stacked structure of two ferromagnetic materials.

7. The magnetic tunnel junction structure of claim 1, further comprising a cap layer on the free layer.

8. A magnetic tunnel junction structure of a Magnetic Random Access Memory (MRAM) device, comprising:

a lower electrode that comprises a Ti-rich TiN layer having a titanium (Ti) content of between about 70 and about 90 atomic percent, the Ti-rich TiN layer having a lower chemical mechanical polishing rate than a stoichiometric TiN layer and having a surface roughness that is also lower than a stoichiometric TiN layer; and

a magnetic tunnel junction on the lower electrode, the magnetic tunnel junction comprising a seed layer and a tunneling barrier that is oriented in a same direction as a most closely packed plane direction of the seed layer, the surface roughness of the tunneling barrier being reduced by the lower surface roughness of the Ti-rich TiN layer.

9. A structure of claim 8 further comprising an oxide layer between the lower electrode and the magnetic tunnel junction.

10. A magnetic tunnel junction structure of a Magnetic Random Access Memory (MRAM) device, comprising:

a lower electrode that comprises a Ti-rich TiN layer having a titanium (Ti) content of between about 70 and about 90 atomic percent, the Ti-rich TiN layer having a lower chemical mechanical polishing rate than a stoichiometric TiN layer and having a surface roughness that is also lower than a stoichiometric TiN layer;

an oxide layer on the lower electrode; and

a magnetic tunnel junction on the oxide layer.

11. A magnetic tunnel junction structure of a Magnetic Random Access Memory (MRAM) device, comprising:

a lower electrode that comprises a Ti-rich TiN layer having a titanium (Ti) content of between about 70 and about 90 atomic percent, the Ti-rich TiN layer having a lower chemical mechanical polishing rate than a stoichiometric TiN layer and having a surface roughness that is also lower than a stoichiometric TiN layer; and

a magnetic tunnel junction on the lower electrode.

12. A structure of claim 11 wherein the magnetic tunnel junction comprises a seed layer and a tunneling barrier that is oriented in a same direction as a most closely packed plane direction of the seed layer.

13. A magnetic tunneling junction structure of a Magnetic Random Access Memory (MRAM) device, comprising:

a lower electrode that comprises a Ti-rich TiN layer having a titanium (Ti) content of between about 70 and about 90 atomic percent, the Ti-rich TiN layer having a lower chemical mechanical polishing rate than a stoichiometric TiN layer and having a surface roughness that is also lower than a stoichiometric TiN layer; and

a magnetic tunnel junction on the lower electrode, the magnetic tunnel junction comprising a seed layer and a tunneling barrier that is oriented in a same direction as a most closely packed plane direction of the seed layer, the surface roughness of the tunneling barrier being reduced by the lower surface roughness of the Ti-rich TiN layer.

14. A structure of claim 13, further comprising an oxide layer between the lower electrode and the magnetic tunnel junction.