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US-20260130120-A1 - MRAM AND FABRICATING METHOD OF THE SAME

US20260130120A1US 20260130120 A1US20260130120 A1US 20260130120A1US-20260130120-A1

Abstract

An MRAM includes a bottom electrode, a magnetic tunnel junction, a cap layer and a top electrode stacked in sequence from bottom to top. The magnetic tunnel junction includes a free layer. The cap layer includes a mixture layer. The mixture layer includes a magnesium layer, a magnesium oxide layer, a tantalum oxide layer and a first tantalum layer. The mixture layer contacts the free layer.

Inventors

  • Yi-Ching Wang
  • Chia-Fu Cheng
  • Tzu-Hung Yang
  • Wei Chen
  • Chun-Yao Yang

Assignees

  • UNITED MICROELECTRONICS CORP.

Dates

Publication Date
20260507
Application Date
20241223
Priority Date
20241105

Claims (20)

  1. 1 . A magnetoresistive random access memory (MRAM), comprising: a bottom electrode, a magnetic tunnel junction, a cap layer and a top electrode stacked in sequence from bottom to top, wherein the magnetic tunnel junction comprises a free layer, and wherein the cap layer comprises a mixture layer, the mixture layer comprises a magnesium layer, a magnesium oxide layer, a tantalum oxide layer and a first tantalum layer, and the mixture layer contacts the free layer.
  2. 2 . The MRAM of claim 1 , wherein the mixture layer comprises a top surface and a bottom surface, and the top surface and the bottom surface are opposite to each other, the bottom surface contacts the free layer, and the top surface is closer to the top electrode than the bottom surface, the mixture layer has an oxygen atom concentration, the oxygen atom concentration decreases continuously from a middle of the mixture layer respectively toward the top surface and the bottom surface.
  3. 3 . The MRAM of claim 1 , wherein the mixture layer comprises a bottom surface, the bottom surface contacts the free layer, the mixture layer has an oxygen atom concentration, the oxygen atom concentration increases continuously from the bottom surface toward the top electrode.
  4. 4 . The MRAM of claim 1 , wherein the magnetic tunnel junction further comprising: a pinned layer, a reference layer and an oxide layer stacked from bottom to top, and the oxide layer contacts the free layer.
  5. 5 . The MRAM of claim 4 , wherein the pinned layer comprises PtMn, IrMn or PtIr, the reference layer and the free layer respectively comprise Fe, Co, Ni, FeNi, FeCo, CoNi, FeB, FePt, FePd or CoFeB, and the oxide layer comprises MgO, Al 2 O 3 , NiO, GdO, Ta 2 O 5 , MoO 2 , TiO 2 or WO 2 .
  6. 6 . The MRAM of claim 1 , wherein the top electrode and the bottom electrode respectively comprise Ti, Ta, TiN, TaN, W, Cu or Al, the cap layer further comprises a first metal layer, a second metal layer and a third metal layer sequentially stacked from bottom to top on the mixture layer, the first metal layer, the second metal layer and the third metal layer respectively comprise Ru, Ta, V, Mn, Zn, Mo, W, Re or Os.
  7. 7 . A fabricating method of a magnetoresistive random access memory (MRAM), comprising: forming a bottom electrode, a magnetic tunnel junction, a cap layer and a top electrode stacked in sequence from bottom to top, wherein the magnetic tunnel junction comprises a free layer, and fabricating steps of the cap layer comprise: depositing a magnesium layer; providing oxygen gas and heating the magnesium layer to make the oxygen gas react with part of the magnesium layer to form a magnesium oxide layer; and after forming the magnesium oxide layer, depositing a first tantalum layer to cover the magnesium layer and the magnesium oxide layer to make some of oxygen atoms in the magnesium oxide layer diffuse into the first tantalum layer to form a tantalum oxide layer.
  8. 8 . The fabricating method of a MRAM of claim 7 , wherein the magnesium layer, the magnesium oxide layer, the tantalum oxide layer and the first tantalum layer form a mixture layer, and the mixture layer contacts the free layer.
  9. 9 . The fabricating method of a MRAM of claim 8 , wherein the mixture layer comprises a top surface and a bottom surface, and the top surface and the bottom surface are opposite to each other, the bottom surface contacts the free layer, and the top surface is closer to the top electrode than the bottom surface, the mixture layer has an oxygen atom concentration, the oxygen atom concentration decreases continuously from a middle of the mixture layer respectively toward the top surface and the bottom surface.
  10. 10 . The fabricating method of a MRAM of claim 7 , wherein before heating the magnesium layer, the magnesium layer has a first thickness, before heating the first tantalum layer, the first tantalum layer has a second thickness, and the first thickness is greater than the second thickness.
  11. 11 . The fabricating method of a MRAM of claim 10 , wherein the first thickness is 3 times the second thickness.
  12. 12 . The fabricating method of a MRAM of claim 7 , wherein the magnetic tunnel junction further comprising: a pinned layer, a reference layer and an oxide layer stacked from bottom to top, and the oxide layer contacts the free layer, and wherein the pinned layer comprises PtMn, IrMn or PtIr, the reference layer and the free layer respectively comprise Fe, Co, Ni, FeNi, FeCo, CoNi, FeB, FePt, FePd or CoFeB, the oxide layer comprises MgO, Al 2 O 3 , NiO, GdO, Ta 2 O 5 , MoO 2 , TiO 2 or WO 2 , the top electrode and the bottom electrode respectively comprise Ti, Ta, TiN, TaN, W, Cu or Al, the cap layer further comprises a first metal layer, a second metal layer and a third metal layer sequentially stacked from bottom to top on the magnesium layer, the magnesium oxide layer, the first tantalum layer and the tantalum oxide layer, and the first metal layer, the second metal layer and the third metal layer respectively comprise Ru, Ta, V, Mn, Zn, Mo, W, Re or Os.
  13. 13 . The fabricating method of a MRAM of claim 7 , wherein the magnesium layer and the first tantalum layer are deposited by physical vapor deposition.
  14. 14 . A fabricating method of a magnetoresistive random access memory (MRAM), comprising: forming a bottom electrode, a magnetic tunnel junction, a cap layer and a top electrode stacked in sequence from bottom to top, wherein the magnetic tunnel junction comprises a free layer, and fabricating steps of the cap layer comprise: depositing a magnesium layer and a first tantalum layer in a listed sequence; and providing oxygen gas and heating the magnesium layer and the first tantalum layer to make oxygen react with part of the magnesium layer and part of the first tantalum layer to form a magnesium oxide layer and a tantalum oxide layer.
  15. 15 . The fabricating method of a MRAM of claim 14 , wherein the magnesium layer, the magnesium oxide layer, the tantalum oxide layer and the first tantalum layer form a mixture layer, and the mixture layer contacts the free layer.
  16. 16 . The fabricating method of a MRAM of claim 15 , wherein the mixture layer comprises a bottom surface, the bottom surface contacts the free layer, the mixture layer has an oxygen atom concentration, the oxygen atom concentration increases continuously from the bottom surface toward the top electrode.
  17. 17 . The fabricating method of a MRAM of claim 14 , wherein before heating the magnesium layer and the first tantalum layer, the magnesium layer has a first thickness, the first tantalum layer has a second thickness, and the first thickness is greater than the second thickness.
  18. 18 . The fabricating method of a MRAM of claim 17 , wherein the first thickness is 3 times the second thickness.
  19. 19 . The fabricating method of a MRAM of claim 14 , wherein the magnetic tunnel junction further comprising: a pinned layer, a reference layer and an oxide layer stacked from bottom to top, and the oxide layer contacts the free layer, and wherein the pinned layer comprises PtMn, IrMn or PtIr, the reference layer and the free layer respectively comprise Fe, Co, Ni, FeNi, FeCo, CoNi, FeB, FePt, FePd or CoFeB, the oxide layer comprises MgO, Al 2 O 3 , NiO, GdO, Ta 2 O 5 , MoO 2 , TiO 2 or WO 2 , the top electrode and the bottom electrode respectively comprise Ti, Ta, TiN, TaN, W, Cu or Al, the cap layer further comprises a first metal layer, a second metal layer and a third metal layer sequentially stacked from bottom to top on the magnesium layer, the magnesium oxide layer, the first tantalum layer and the tantalum oxide layer, and the first metal layer, the second metal layer and the third metal layer respectively comprise Ru, Ta, V, Mn, Zn, Mo, W, Re or Os.
  20. 20 . The fabricating method of a MRAM of claim 14 , wherein the magnesium layer and the first tantalum layer are deposited by physical vapor deposition.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetoresistive random access memory (MRAM), and a fabricating method of the same, and more particularly to an MRAM having high tunnel magnetoresistance (TMR) and coercivity, and a fabricating method of the same. 2. Description of the Prior Art Many modern electronic devices contain electronic memory configured to store data. Electronic memory may be volatile memory or non-volatile memory. Volatile memory stores data only while it is powered, while non-volatile memory is able to store data even when power is off. In addition, process shrinkage is an important trend in advanced semiconductor manufacturing processes. Under this trend, because magnetoresistive random access memory (MRAM) has high read and write speeds, low power consumption, and can store data even when power is off, the MRAM is particularly suitable for the embedded system. Since MRAM has superior advantages than other electronic memories, its potential in the next generation of non-volatile memory technology is expected. MRAM does not use electrons to store bit information, but uses magnetic polarization to store data. During a write mode, the magnetic material can be switched between two opposite magnetic states through an external magnetic field to store data. However, conventional MRAM still needs to be improved. For example, increasing the magnetic moment switch speed, the tunnel magnetoresistance (TMR) and coercivity of MRAM to raise the operating performance of MRAM is an object of the semiconductor industry. SUMMARY OF THE INVENTION In view of this, the present invention provides an MRAM with special components in a cap layer to increase the magnetic moment switch speed, tunnel magnetoresistance and coercivity of the MRAM. According to a preferred embodiment of the present invention, an MRAM includes a bottom electrode, a magnetic tunnel junction, a cap layer and a top electrode stacked in sequence from bottom to top. The magnetic tunnel junction includes a free layer. The cap layer includes a mixture layer. The mixture layer includes a magnesium layer, a magnesium oxide layer, a tantalum oxide layer and a first tantalum layer, and the mixture layer contacts the free layer. A fabricating method of an MRAM includes forming a bottom electrode, a magnetic tunnel junction, a cap layer and a top electrode stacked in sequence from bottom to top. The magnetic tunnel junction includes a free layer. Fabricating steps of the cap layer include depositing a magnesium layer. Next, oxygen gas is provided and the magnesium layer is heated to make the oxygen gas react with part of the magnesium layer to form a magnesium oxide layer. After the magnesium oxide layer is formed, a first tantalum layer is deposited to cover the magnesium layer and the magnesium oxide layer to make some of oxygen atoms in the magnesium oxide layer diffuse into the first tantalum layer to form a tantalum oxide layer. A fabricating method of an MRAM includes forming a bottom electrode, a magnetic tunnel junction, a cap layer and a top electrode stacked in sequence from bottom to top. The magnetic tunnel junction includes a free layer. Fabricating steps of the cap layer include depositing a magnesium layer and a first tantalum layer in a listed sequence. Then, oxygen gas is provided and the magnesium layer and the first tantalum layer are heated to make oxygen react with part of the magnesium layer and part of the first tantalum layer to form a magnesium oxide layer and a tantalum oxide layer. These and other objectives of the present invention will no doubt become obvious to those of ordinary skill in the art after reading the following detailed description of the preferred embodiment that is illustrated in the various figures and drawings. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 to FIG. 2 depict a fabricating method of an MRAM according to a preferred embodiment of the present invention, wherein: FIG. 2 depicts fabricating steps in continuous of FIG. 1 FIG. 3 to FIG. 5 depict a fabricating method of a cap layer according to a first preferred embodiment of the present invention, wherein: FIG. 4 depicts fabricating steps in continuous of FIG. 3; and FIG. 5 depicts fabricating steps in continuous of FIG. 4. FIG. 6 to FIG. 8 depict a fabricating method of a cap layer according to a second preferred embodiment of the present invention, wherein: FIG. 7 depicts fabricating steps in continuous of FIG. 6; and FIG. 8 depicts fabricating steps in continuous of FIG. 7. FIG. 9 is a concentration distribution chart of magnesium atoms, oxygen atoms and tantalum atoms in the mixture layer according to the first preferred embodiment of the present invention. FIG. 10 is a concentration distribution chart of magnesium atoms, oxygen atoms and tantalum atoms in the mixture layer according to the second preferred embodiment of the present invention. DETAILED DESCRIPTION FIG. 1 to FIG. 2 depict a fabricatin