BiSb topological insulator with novel buffer layer that promotes a BiSb (012) orientation
A spin-orbit torque (SOT) magnetic tunnel junction (MTJ) device includes a substrate, a buffer layer formed over the substrate, and a bismuth antimony (BiSb) layer formed over the buffer layer, the BiSb layer having a (012) orientation. In certain embodiments, the SOT MTJ device is part of a microwave assisted magnetic recording (MAMR) write head. In certain embodiments, the SOT MTJ device is part of a magnetoresistive random access memory (MRAM) device.
1. A spin-orbit torque (SOT) magnetic tunnel junction (MTJ) device, comprising:
a substrate;
a buffer layer formed over the substrate, the buffer layer comprising:
a pre-seed layer over the substrate, the pre-seed layer comprising a material selected from a group consisting of NiTa, NiFeTa, CoZrTa, NiNb, NiFeTa, NiFeW, CoHf, CoFeHf, CoFeHfB, NiFeB, CoFeB, Ge, Co, CoFe, NiCr, Ni, Cu, NiFe, Ru, Pt, Rh, silicon oxide, aluminum oxide, magnesium oxide, TiN, AlN, and alloys thereof;
a seed layer over the pre-seed layer, the seed layer comprising a material selected from a group consisting of Co, CoFe, Ni, NiFe, NiCr, NiTa, NiFeTa, Cu, CuAgNi, RuX, CuX, CuNiX, CoFeX, CoNiX, FeX, NiX, and CoX, wherein X is selected from the group consisting of Cr, Ag, Pt, Ir, Rh, and combinations thereof; and
a crystalline layer over the seed layer, the crystalline layer comprising a material selected from a group consisting of Co, CoFe, Ni, NiFe, NiCr, NiTa, NiFeTa, Cu, CuAgNi, RuX, CuX, CuNiX, CoFeX, CoNiX, FeX, NiX, and CoX, wherein X is selected from the group consisting of Cr, Ag, Pt, Ir, Rh, and combinations thereof; and
a bismuth antimony (BiSb) layer formed over the buffer layer, the BiSb layer having a (012) orientation.
2. The SOT MTJ device of claim 1 , wherein the pre-seed layer comprises a material selected from a group consisting of NiTa, NiFeTa, NiCr, Co, CoFe, Cu, NiFe, and alloys thereof.
3. The SOT MTJ device of claim 1 , wherein the crystalline layer comprises a material selected from a group consisting of Co, CoFe, Ni, NiFe, Cu, CuNiAg, and alloys thereof.
4. The SOT MTJ device of claim 1 , wherein the material of the seed layer and the material of the crystalline layer have a (111) orientation with an a-axis from about 3.52 Å to about 3.71 Å.
5. The SOT MTJ device of claim 1 , wherein the material of the seed layer and the material of the crystalline layer have a (002) orientation with an a-axis from about 2.49 Å to 2.62 Å.
6. The SOT MTJ device of claim 1 , wherein the BiSb layer comprises antimony in an atomic percent content from about 5% to about 20%.
7. The SOT MTJ device of claim 1 , wherein the substrate is selected from a group consisting of silicon and alumina.
8. The SOT MTJ device of claim 1 , further comprising an electrical current shunt blocking layer comprising a magnetic material.
9. The SOT MTJ device of claim 8 , wherein the magnetic material of the electrical current shunt blocking layer is selected from a group consisting of FeCo, FeCoM, FeCoMO, FeCoMMeO, FeCoM/MeO stack, FeCoMNiMnMgZnFeO, FeCoM/NiMnMgZnFeO stack, multiple layers thereof, multiple stacks thereof, and combinations thereof in which M is one or more of B, Si, P, Al, Hf, Zr, Nb, Ti, Ta, Mo, Mg, Y, Cu, Cr, and Ni, and Me is Si, Al, Hf, Zr, Nb, Ti, Ta, Mg, Y, or Cr.
10. A microwave assisted magnetic recording (MAMR) write head, comprising:
a main pole and a trailing shield; and
a spin-orbit torque (SOT) device disposed in a gap between the main pole and the trailing shield, the SOT device comprising:
a substrate;
a buffer layer formed over the substrate, wherein the buffer layer comprises:
a pre-seed layer over the substrate, the pre-seed layer comprising a material selected form a group consisting of NiTa, NiFeTa, CoZrTa, NiNb, NiFeTa, NiFeW, CoHf, CoFeHf, CoFeHfB, NiFeB, CoFeB, Ge, Co, CoFe, NiCr, Ni, Cu, NiFe, Ru, Pt, Rh, silicon oxide, aluminum oxide, magnesium oxide, TiN, AlN, and alloys thereof;
a seed layer over the pre-seed layer, the seed layer comprising a material selected from a group consisting of Co, CoFe, Ni, NiFe, NiCr, NiTa, NiFeTa, Cu, CuAgNi, RuX, CuX, CuNiX, CoFeX, CoNiX, FeX NiX, and CoX, wherein X is selected from the group consisting of Cr, Ag, Pt, Ir, Rh, and combinations thereof; and
a crystalline layer over the seed layer, the crystalline layer comprising a material selected from a group consisting of Co, CoFe, Ni, NiFe, NiCr, NiTa, NiFeTa, Cu, CuAgNi, RuX, CuX, CuNiX, CoFeX, CoNiX, FeX NiX, and CoX, wherein X is selected from the group consisting of Cr, Ag, Pt, Ir, Rh, and combinations thereof;
a bismuth antimony (BiSb) layer over the buffer layer, wherein the BiSb layer has a (012) orientation and is a spin Hall layer; and
a spin torque layer formed over the BiSb layer.
11. The MAMR write head of claim 10 , wherein the crystalline layer comprises a material selected from a group consisting of Co, CoFe, Ni, NiFe, Cu, CuNiAg, and alloys thereof.
12. The MAMR write head of claim 10 , further comprising an electrical current shunt blocking layer between the BiSb layer and the spin torque layer, the electrical current shunt blocking layer comprising a magnetic material.
13. The MAMR write head of claim 12 , wherein the electrical current shunt blocking layer comprises a magnetic material selected from a group consisting of FeCo, FeCoM, FeCoMO, FeCoMMeO, FeCoM/MeO stack, FeCoMNiMnMgZnFeO, FeCoM/NiMnMgZnFeO stack, multiple layers thereof, multiple stacks thereof, and combinations thereof in which M is one or more of B, Si, P, Al, Hf, Zr, Nb, Ti, Ta, Mo, Mg, Y, Cu, Cr, and Ni, and Me is Si, Al, Hf, Zr, Nb, Ti, Ta, Mg, Y, or Cr.
14. A magnetic media drive comprising the MAMR write head of claim 10 .
15. The MAMR write head of claim 10 , wherein the material of the seed layer and the material of the crystalline layer have a (111) orientation with an a-axis from about 3.52 Å to about 3.71 Å.
16. A magnetoresistive random access memory (MRAM) device, comprising
a recording layer;
a buffer layer formed over the recording layer, wherein the buffer layer comprises:
a pre-seed layer over the recording layer, the pre-seed layer comprising a material selected form a group consisting of NiTa, NiFeTa, CoZrTa, NiNb, NiFeTa, NiFeW, CoHf, CoFeHf, CoFeHfB, NiFeB, CoFeB, Ge, Co, CoFe, NiCr, Ni, Cu, NiFe, Ru, Pt, Rh, silicon oxide, aluminum oxide, magnesium oxide, TiN, AlN, and alloys thereof;
a seed layer over the pre-seed layer, the seed layer comprising a material selected from a group consisting of Co, CoFe, Ni, NiFe, NiCr, NiTa, NiFeTa, Cu, CuAgNi, RuX, CuX, CuNiX, CoFeX, CoNiX, FeX NiX, and CoX, wherein X is selected from the group consisting of Cr, Ag, Pt, Ir, Rh, and combinations thereof; and
a crystalline layer over the seed layer, the crystalline layer comprising a material selected from a group consisting of Co, CoFe, Ni, NiFe, NiCr, NiTa, NiFeTa, Cu, CuAgNi, RuX, CuX, CuNiX, CoFeX, CoNiX, FeX NiX, and CoX, wherein X is selected from the group consisting of Cr, Ag, Pt, Ir, Rh, and combinations thereof; and
a bismuth antimony (BiSb) layer formed over the buffer layer, the BiSb layer having a (012) orientation.
17. The MRAM device of claim 16 , wherein the crystalline layer comprises a material selected from a group consisting of Co, CoFe, Ni, NiFe, Cu, CuNiAg, and alloys thereof.
18. The MRAM device of claim 16 , further comprising an electrical current shunt blocking layer between the buffer layer and the recording layer, the electrical current shunt blocking layer comprising a magnetic material.
19. The MRAM device of claim 18 , wherein the electrical current shunt blocking layer comprises a magnetic material selected from a group consisting of FeCo, FeCoM, FeCoMO, FeCoMMeO, FeCoM/MeO stack, FeCoMNiMnMgZnFeO, FeCoM/NiMnMgZnFeO stack, multiple layers thereof, multiple stacks thereof, and combinations thereof in which M is one or more of B, Si, P, Al, Hf, Zr, Nb, Ti, Ta, Mo, Mg, Y, Cu, Cr, and Ni, and Me is Si, Al, Hf, Zr, Nb, Ti, Ta, Mg, Y, or Cr.
20. The MRAM device of claim 16 , wherein the material of the seed layer and the material of the crystalline layer have a (002) orientation with an a-axis from about 2.49 Å to 2.62 Å.