Maintaining Coercive Field after High Temperature Anneal for Magnetic Device Applications with Perpendicular Magnetic Anisotropy

Patent metadata

Field	Value
Publication number	US-2020028073-A1
Application number	US-201916587927-A
Country	US
Kind code	A1
Filing date	Sep 30, 2019
Priority date	Apr 3, 2017
Publication date	Jan 23, 2020
Grant date	—

Abstract

A magnetic tunnel junction with perpendicular magnetic anisotropy (PMA MTJ) is disclosed wherein a free layer interfaces with a tunnel barrier and has a second interface with an oxide layer. A lattice-matching layer adjoins an opposite side of the oxide layer with respect to the free layer and is comprised of CoXFeYNiZLWMV or an oxide or nitride of Ru, Ta, Ti, or Si, wherein L is one of B, Zr, Nb, Hf, Mo, Cu, Cr, Mg, Ta, Ti, Au, Ag, or P, and M is one of Mo, Mg, Ta, Cr, W, or V, (x+y+z+w+v)=100 atomic %, x+y>0, and each of v and w are >0. The lattice-matching layer grows a BCC structure during annealing thereby promoting BCC structure growth in the oxide layer that results in enhanced free layer PMA and improved thermal stability.

First claim

What is claimed is:

1 . A method of forming a magnetic memory element with a stack of layers, the method comprising:
sequentially depositing a reference layer, a tunnel barrier, and a free layer on a substrate, wherein the free layer forms a first interface with the tunnel barrier thereby inducing or enhancing perpendicular magnetic anisotropy (PMA) in the free layer; forming an oxide layer on a top surface of the free layer to form a second interface that induces or enhances PMA in the free layer; forming a first lattice-matching layer on the oxide layer; depositing a hard mask as an uppermost layer in the stack of layers; and annealing the stack of layers at a temperature proximate to 400° C. so that the first lattice-matching layer grows a body centered cubic (BCC) structure.

2 . The method of claim 1 , wherein the first lattice-matching layer has an amorphous structure prior to the annealing.

3 . The method of claim 1 , wherein the first lattice-matching layer includes a material having a composition denoted as Co X Fe Y Ni Z L W M V , wherein L is a non-magnetic material, wherein M is one or more of Mo, Mg, Ta, Cr, W, Ru, and V, wherein (x+y) is greater than zero, wherein each of v and w is greater than zero, and wherein (x+y+z+w+v) is equal to 100 atomic %.

4 . The method of claim 3 , wherein L is one of B, Zr, Nb, Hf, Mo, Cu, Cr, Mg, Ta, Ti, Au, Ag, or P.

5 . The method of claim 1 , further comprising depositing a second lattice-matching layer on the first lattice-matching layer before depositing the hard mask, wherein the second lattice-matching layer comprises one or more of Mo, Mg, Ta, Cr, W, Ru, and V.

6 . The method of claim 5 , wherein the second lattice-matching layer is a single material layer having a composition denoted as Co X Fe Y Ni Z L W M V , wherein L is a non-magnetic material, wherein M is one or more of Mo, Mg, Ta, Cr, W, Ru, and V, wherein (x+y) is greater than zero, wherein each of v and w is greater than zero, and wherein (x+y+z+w+v) is equal to 100 atomic %.

7 . The method of claim 5 , wherein the second lattice-matching layer is a bilayer stack of materials having a first layer and a second layer, wherein the first layer has a composition denoted as Co X Fe Y Ni Z L W M V , wherein L is a non-magnetic material, wherein M is one or more of Mo, Mg, Ta, Cr, W, Ru, and V, wherein (x+y) is greater than zero, wherein each of v and w is greater than zero, and wherein (x+y+z+w+v) is equal to 100 atomic %, wherein the second layer is one or more of Mo, Mg, Ta, Cr, W, Ru, and V, and wherein the second layer physically contacts the hard mask.

8 . The method of claim 1 , wherein the oxide layer is one of MgTaOx, MgO, SiOx, SrTiOx, BaTiOx, CaTiOx, LaAlOx, MnOx, VOx, Al 2 O 3 , TiOx, BOx, and HfOx, or is a laminate of one or more of the aforementioned oxides.

9 . The method of claim 1 , wherein the substrate is a bottom electrode in a Magnetoresistive Random Access Memory (MRAM) device or in a spin-torque MRAM.

10 . The method of claim 1 , wherein the substrate is a main pole layer in a spin torque oscillator (STO) device.

11 . The method of claim 1 , wherein the first lattice-matching layer is an oxide or nitride of Ru, Ta, Ti, or Si.

12 . A method of forming a magnetic memory element with a stack of layers, the method comprising:
depositing a first lattice-matching layer on a substrate, the first lattice-matching layer including a material selected from the group consisting of Mo, Mg, Ta, Cr, W, Ru, V, and combinations thereof; depositing a second lattice-matching layer on the first lattice-matching layer, wherein the second lattice-matching layer has an amorphous structure when deposited on the first lattice-matching layer; forming an oxide layer on the second lattice-matching layer; depositing a free layer that contacts a top surface of the oxide layer to form a first interface which induces or enhances perpendicular magnetic anisotropy (PMA) in the free layer; sequentially forming a tunnel barrier, reference layer, and a hard mask on the free layer, wherein the tunnel barrier contacts a top surface of the free layer to form a second interface that induces or enhances PMA in the free layer; and annealing the stack of layers at a temperature of about 400° C. so that the second lattice-matching layer grows a body centered cubic (BCC) structure.

13 . The method of claim 12 , wherein the first lattice-matching layer includes a material having a composition denoted as Co X Fe Y Ni Z L W , wherein L is a non-magnetic material, wherein (x+y) is greater than zero, wherein w is greater than zero, and wherein (x+y+z+w) is equal to 100 atomic %.

14 . The method of claim 13 , wherein L is one of B, Zr, Nb, Hf, Mo, Cu, Cr, Mg, Ta, Ti, Au, Ag, or P.

15 . The method of claim 12 , wherein the oxide layer is one of MgTaOx, MgO, SiOx, SrTiOx, BaTiOx, CaTiOx, LaAlOx, MnOx, VOx, Al 2 O 3 , TiOx, BOx, and HfOx, or is a laminate of one or more of the aforementioned oxides.

16 . The method of claim 12 , wherein depositing the second lattice-matching layer on the first lattice-matching layer forms a single lattice-matching layer having a composition denoted as Co X Fe Y Ni Z L W M V , wherein L is a non-magnetic material, wherein M is one or more of Mo, Mg, Ta, Cr, W, Ru, and V, wherein (x+y) is greater than zero, wherein each of v and w is greater than zero, and wherein (x+y+z+w+v) is equal to 100 atomic %.

17 . The method of claim 12 , further comprising depositing a third lattice matching layer on the second lattice-matching layer before the oxide layer is deposited, wherein the third lattice matching layer is an oxide or nitride of Ru, Ta, Ti, or Si.

18 . A method of forming a magnetic memory element with a stack of layers, the method comprising:
depositing a first lattice-matching layer on a substrate, the first lattice-matching layer including a material selected from the group consisting of Mo, Mg, Ta, Cr, W, Ru, V, and combinations thereof; depositing a second lattice-matching layer having a multi-layer structure on the first lattice-matching layer, wherein the second lattice-matching layer has an amorphous structure when deposited on the first lattice-matching layer; forming an oxide layer on the second lattice-matching layer; depositing a free layer that contacts a top surface of the oxide layer to form a first interface which induces or enhances perpendicular magnetic anisotropy (PMA) in the free layer; sequentially forming a tunnel barrier, reference layer, and a hard mask on the free layer, wherein the tunnel barrier contacts a top surface of the free layer to form a second interface that induces or enhances PMA in the free layer; and annealing the stack of layers at a temperature of about 400° C. so that the second lattice-matching layer grows a body centered cubic (BCC) structure.

19 . The method of claim 18 , wherein the multi-layer structure is a bilayer structure having a M/Co X Fe Y Ni Z L W or a M/Co X Fe Y Ni Z L W M V configuration, wherein L is a non-magnetic material, wherein M is one or more of Mo, Mg, Ta, Cr, W, Ru, and V, wherein the Co X Fe Y Ni Z L W M V or Co X Fe Y Ni Z L W layer of the bilayer structure contacts the oxide layer, and wherein the Co X Fe Y Ni Z L W M V or Co X Fe Y Ni Z L W layer of the bilayer structure grows the BCC structure during the annealing of the stack of layers.

20 . The method of claim 18 , wherein the multi-layer structure is tri-layer structure having a M/Co X Fe Y Ni Z L W M V /Co X Fe Y Ni Z L W configura

Assignees

• Taiwan Semiconductor Mfg Co Ltd

Inventors

• Liu Huanlong
• Lee Yuan-Jen
• Zhu Jian
• Jan Guenole
• Thomas Luc
• Wang Po-Kang
• Tong Ru-Ying
• Iwata Jodi

Classifications

• H01F41/14

  for applying magnetic films to substrates · CPC title

• H01F10/14

  containing iron or nickel ({H01F10/126} , H01F10/13, H01F10/16 take precedence) · CPC title

• H01F10/32

  Spin-exchange-coupled multilayers, e.g. nanostructured superlattices {(applying spin-exchange-coupled multilayers to substrates H01F41/302)} · CPC title

• H01L43/12 Primary

  Electricity · mapped topic

• H01L43/02

  Electricity · mapped topic