US 10680167

Here's a concise summary of US patent 10680167:

US Patent: 10680167

• Title: Magnetic tunnel junction device
• Assignee: The original assignees were Japan Science and Technology Agency and National Institute of Advanced Industrial Science and Technology AIST. As of November 22, 2022, the patent was assigned to Godo Kaisha IP Bridge 1. Subsequently, on April 18, 2025, it was reassigned to National Institute of Advanced Industrial Science and Technology and Japan Science and Technology Agency.
• Inventors: Shinji Yuasa
• Filing Date: June 18, 2019 (Application number US16/443,875)
• Issue Date: June 9, 2020
• Abstract: The patent describes a method to increase the output voltage of a Magnetoresistive Random Access Memory (MRAM) by using a specific Magnetic Tunnel Junction (MTJ) device. This MTJ device, often an Fe(001)/MgO(001)/Fe(001) structure, is fabricated by preparing a single-crystalline MgO(001) substrate, growing an epitaxial Fe(001) lower electrode on an MgO(001) seed layer (followed by annealing), and then epitaxially forming an MgO(001) barrier layer using electron-beam evaporation. A Fe(001) upper electrode is then formed, followed by a Co layer to enhance the coercive force for antiparallel magnetization alignment.
• Legal Status Note: The patent is currently listed as "Expired - Lifetime" with an anticipated expiration date of March 10, 2025. Given the current date of April 26, 2026, the patent has expired. The patent family also shows records of litigation, including US cases filed in the Delaware District Court, California Eastern District Court, Minnesota District Court, and a PTAB case (IPR2024-01493).

Plain-Language Overview of Independent Claims:

• Independent Claim 1: This claim describes a manufacturing method for a Magnetic Tunnel Junction (MTJ) device. The method involves initially forming an amorphous first CoFeB layer, then forming a magnesium oxide (MgO) layer on top of it, and finally forming another amorphous second CoFeB layer over the MgO layer. Crucially, an annealing step follows, which causes both the first and second CoFeB layers to crystallize. The MgO layer, after this process, is a poly-crystalline structure where the (001) crystal plane is preferentially oriented.
• Independent Claim 11: This claim also outlines a manufacturing method for an MTJ device, similar to Claim 1. It starts by forming a first ferromagnetic layer that includes an amorphous first CoFeB layer. A barrier layer, which includes a magnesium oxide (MgO) layer, is formed over this first ferromagnetic layer, resulting in a poly-crystalline state with a preferentially oriented (001) crystal plane. Subsequently, a second ferromagnetic layer including an amorphous second CoFeB layer is formed over the barrier layer. Finally, an annealing step crystallizes the first and second CoFeB layers.

Known litigation involving US patent 10680167 as of April 26, 2026, is detailed below. Please note that specific plaintiff(s), defendant(s), and precise filing dates are not explicitly provided in the patent document itself but are indicated as being available via the cited Unified Patents portal.

1. Jurisdiction: Delaware District Court

   • Case Number: 1:24-cv-00342
   • Plaintiff(s): Not specified in the provided patent text.
   • Defendant(s): Not specified in the provided patent text.
   • Filing Date: Not specified in the provided patent text.
   • Outcome or Current Status: Listed as "Critical" litigation.

2. Jurisdiction: California Eastern District Court

   • Case Number: 3:24-cv-06555
   • Plaintiff(s): Not specified in the provided patent text.
   • Defendant(s): Not specified in the provided patent text.
   • Filing Date: Not specified in the provided patent text.
   • Outcome or Current Status: Listed as active "litigation."

3. Jurisdiction: California Eastern District Court

   • Case Number: 4:24-cv-06555
   • Plaintiff(s): Not specified in the provided patent text.
   • Defendant(s): Not specified in the provided patent text.
   • Filing Date: Not specified in the provided patent text.
   • Outcome or Current Status: Listed as active "litigation."
   • Note: This case number is highly similar to the previous one, differing only in the first digit. It is presented as a distinct entry in the source.

4. Jurisdiction: Patent Trial and Appeal Board (PTAB)

   • Case Number: IPR2024-01493
   • Plaintiff(s) / Petitioner(s): "Petitioner:" (name not specified in the provided patent text).
   • Defendant(s) / Patent Owner(s): Not specified in the provided patent text.
   • Filing Date: Not specified in the provided patent text.
   • Outcome or Current Status: "Final Written Decision" has been filed.

5. Jurisdiction: Minnesota District Court

   • Case Number: 0:24-cv-03691
   • Plaintiff(s): Not specified in the provided patent text.
   • Defendant(s): Not specified in the provided patent text.
   • Filing Date: Not specified in the provided patent text.
   • Outcome or Current Status: Listed as active "litigation."

Proceedings overview

One AIA trial proceeding has been filed against US Patent 10680167, which has reached a status of "Final Written Decision." The specific claim-level outcomes of this decision are not publicly available in the immediate search results.

IPR2024-01493 — Western Digital Technologies, Inc. et al. v. Godo Kaisha IP Bridge 1

• Type: Inter Partes Review
• Filed: 2024-09-27
• Status: Final Written Decision — the Patent Trial and Appeal Board (PTAB) has issued a final determination on the patentability of the challenged claims.
• Judge panel: The specific judge panel for IPR2024-01493 is not publicly available in the search results.
• Petition grounds: The specific claims challenged and the prior art asserted in the petition for IPR2024-01493 are not publicly available in the search results. However, related IPRs filed by Western Digital Technologies, Inc. against other patents owned by Godo Kaisha IP Bridge 1 often challenge claims as obvious under § 103, frequently using combinations of prior art references.
• Institution decision: Details regarding the institution decision (e.g., date, claims instituted, or reasoning) for IPR2024-01493 are not publicly available in the search results. Related IPR filings from Western Digital against Godo Kaisha IP Bridge 1 indicate petitions were filed, but institution decisions vary.
• Final Written Decision (if issued): While the proceeding status indicates a "Final Written Decision" was issued, the specific verdict at a claim-level granularity (i.e., which claims were canceled or held patentable) and the panel's reasoning for IPR2024-01493 are not publicly available in the search results.
• Settlement / termination: There is no public information in the search results indicating that IPR2024-01493 was terminated via settlement.
• Appeal: There is no public information in the search results indicating whether the Final Written Decision for IPR2024-01493 was appealed to the Federal Circuit.
• Defensive value: Without the specific outcome of the Final Written Decision, the defensive value is uncertain. If claims were invalidated, any infringement theory relying on those claims would be significantly weakened. If claims were sustained, an IPR-based defense would face a higher hurdle.

Strategic summary

Currently, the exact status of claims in US10680167 (whether CANCELED, SUSTAINED, or UNTESTED by the IPR) cannot be determined from the available information, as the contents of the Final Written Decision for IPR2024-01493 are not publicly accessible in the provided search results.

The estoppel landscape under § 315(e)(2) will depend heavily on the outcome of IPR2024-01493. If a Final Written Decision was rendered on the merits, Western Digital Technologies, Inc. (and its privies) would be estopped from asserting in district court or the ITC any ground of unpatentability that they raised or reasonably could have raised during the IPR with respect to any claim found patentable. The litigation between Godo Kaisha IP Bridge 1 and Western Digital Technologies, Inc. in the Northern District of California (transferred from Delaware) suggests a broader patent dispute where IPRs are likely being used defensively. Western Digital Technologies, Inc. has filed multiple IPRs against patents owned by Godo Kaisha IP Bridge 1 related to MRAM technology.

Recommended next steps

Given that a Final Written Decision has been issued for IPR2024-01493, the crucial next step for a defendant is to obtain and review the full Final Written Decision document. This document will contain the specific claim-by-claim disposition and the PTAB's reasoning, which is essential for understanding the patent's current scope and the viability of any ongoing or future infringement assertions. The FWD can typically be found on the USPTO's Patent Trial and Appeal Case Tracking System (P-TACTS) by searching for "IPR2024-01493" (https://ptacts.uspto.gov/#/search/documents). Without this document, the impact of the proceeding on the patent remains unknown.

Inventors

Shinji Yuasa (Japan Science and Technology Agency, National Institute of Advanced Industrial Science and Technology AIST)

Original assignee

The original assignees on the issued patent were Japan Science and Technology Agency and National Institute of Advanced Industrial Science and Technology AIST.

• Japan Science and Technology Agency (JST): JST is a national research and development agency that promotes scientific and technological research in Japan. Their primary line of business is to contribute to scientific and technological advancement and economic and social transformation. They do not directly ship products embodying patent claims, but rather fund and manage research. JST is currently operating.
• National Institute of Advanced Industrial Science and Technology (AIST): AIST is one of the largest public research organizations in Japan. Their primary line of business is to conduct research and development in various fields to support industry and society. They do not directly ship products embodying patent claims. AIST is currently operating.

Assignment timeline

• 2022-11-22 (executed) / recorded 2022-11-22 — Reel 056461/0177
  • Conveyance: Assignment of Assignors Interest
  • Assignor: JAPAN SCIENCE AND TECHNOLOGY AGENCY, NATIONAL INSTITUTE OF ADVANCED INDUSTRIAL SCIENCE AND TECHNOLOGY
  • Assignee: GODO KAISHA IP BRIDGE 1
  • Correspondent: BLANK ROME LLP (ATTORNEYS AT LAW, ONE LOGAN SQUARE, 130 NORTH EIGHTEENTH STREET, PHILADELPHIA, PENNSYLVANIA, UNITED STATES, 19103-6998). This correspondent does not recur in this chain.
  • Context: Transfer-to-asserter
• 2025-04-18 (executed) / recorded 2025-04-18 — Reel 059902/0698
  • Conveyance: Assignment of Assignors Interest
  • Assignor: YUASA, SHINJI
  • Assignee: NATIONAL INSTITUTE OF ADVANCED INDUSTRIAL SCIENCE AND TECHNOLOGY, JAPAN SCIENCE AND TECHNOLOGY AGENCY
  • Correspondent: BIRCH STEWART KOLASCH & BIRCH, LLP (8110 GATEHOUSE ROAD, SUITE 100 EAST, FALLS CHURCH, VIRGINIA, UNITED STATES, 22042). This correspondent does not recur in this chain.
  • Context: Transfer from inventor to original assignees.

Timeline diagram

timeline
    title Ownership of US 10680167
    2019 : Filed by JST and AIST
    2020 : Issued
    2022 : Assigned to Godo Kaisha IP Bridge 1
    2025 : Reassigned to JST and AIST
         : Patent expired

NPE / troll-pattern signals

1. Shell-entity transfer — present. The transfer from Japan Science and Technology Agency and National Institute of Advanced Industrial Science and Technology to Godo Kaisha IP Bridge 1 (Reel 056461/0177) is a strong signal. "Godo Kaisha IP Bridge 1" strongly suggests a licensing-only entity.

2. Known asserter in the chain — present. Godo Kaisha IP Bridge 1 is listed as the current assignee for a period. IP Bridge, Inc. (and entities associated with it) are widely recognized as patent assertion entities by sources such as Unified Patents.

3. Repeat correspondent across the chain — not present. Different correspondents are listed for the two recorded assignments. BLANK ROME LLP for the 2022 assignment (Reel 056461/0177) and BIRCH STEWART KOLASCH & BIRCH, LLP for the 2025 assignment (Reel 059902/0698).

4. Cascading transfers — not present. There are only two recorded assignments, which are not in rapid succession.

5. Pre-litigation transfer — unclear. Multiple litigations are associated with the patent family, but the specific filing dates of the first infringement suits directly naming US10680167 would need to be cross-referenced against the assignment dates to confirm if a transfer occurred within 6 months of a suit.

6. Bankruptcy fire-sale — not present. No indication of bankruptcy for the original assignees or Godo Kaisha IP Bridge 1 is present in the provided information.

7. Privateering — unclear. While Godo Kaisha IP Bridge 1 is a known NPE, and the original assignees are operating entities, the provided information does not contain enough detail to definitively establish a privateering arrangement (e.g., through SEC filings or specific reporting).

8. Defensive aggregator (anti-NPE) — not present. The chain does not terminate at a known defensive aggregator.

Verdict

NPE — high confidence. The presence of Godo Kaisha IP Bridge 1, a known patent assertion entity, as an assignee (Reel 056461/0177), coupled with the clear "shell-entity transfer" signal, strongly indicates an NPE pattern. The reassignment back to the original assignees (Reel 059902/0698) after the patent expired (March 10, 2025) suggests potential post-expiration management or residual interest.

USPTO Assignment Center search for US10680167

To identify the most relevant prior art for US patent 10680167, I will examine the "Citations" section of the patent document, which lists both "Cited By" and "Citations" (prior art cited by the patent itself). Under 35 U.S.C. § 102, prior art must predate the effective filing date of the claimed invention. The priority date for US 10680167 is March 12, 2004, and the filing date is June 18, 2019. Therefore, I will focus on patents and publications with priority or publication dates before March 12, 2004.

Here's an analysis of the most relevant prior art cited within US10680167, focusing on how they might anticipate claims 1 and 11. I will focus on the most relevant prior art, especially those that discuss CoFeB layers and MgO barriers, which are central to the independent claims.

Most Relevant Prior Art for US Patent 10680167

The independent claims (1 and 11) of US10680167 focus on a method of manufacturing an MTJ device involving amorphous CoFeB layers, an MgO layer, and an annealing step that crystallizes the CoFeB and results in a poly-crystalline MgO layer with a preferentially oriented (001) crystal plane. Therefore, prior art that discusses these specific material compositions, layer structures, and manufacturing steps will be most relevant.

Here's an analysis of some key cited prior art:

1. US6181537B1 - Tunnel junction structure with junction layer embedded in amorphous ferromagnetic layers

• Full Citation: US6181537B1.
• Publication/Filing Date: Publication date: January 30, 2001; Priority date: March 29, 1999.
• Brief Description: This patent describes a tunnel junction structure with a junction layer embedded in amorphous ferromagnetic layers. While it mentions amorphous ferromagnetic layers, it generally discusses various tunnel junction materials and does not specifically focus on CoFeB or MgO, especially not in the context of crystallization through annealing to achieve a specific MgO crystallinity.
• Potential Anticipation for Claims 1 and 11: This patent might generally anticipate the concept of using amorphous ferromagnetic layers in an MTJ. However, it does not specifically disclose the use of CoFeB as the amorphous ferromagnetic layer, an MgO tunnel barrier, or the specific annealing step that crystallizes the CoFeB layers and results in a poly-crystalline MgO (001) barrier, which are critical elements of claims 1 and 11. Therefore, it is unlikely to directly anticipate these claims but could be relevant for broader concepts of MTJ structures with amorphous electrodes.

2. JP2000030236A - Perpendicular magnetic recording medium and magnetic recording / reproducing apparatus using the same

• Full Citation: JP2000030236A.
• Publication/Filing Date: Publication date: January 28, 2000; Priority date: July 14, 1998.
• Brief Description: This Japanese patent focuses on perpendicular magnetic recording media and associated apparatus. While it deals with magnetic materials, its primary focus is not on MTJ device structures for MRAMs with specific CoFeB and MgO layers.
• Potential Anticipation for Claims 1 and 11: This patent is unlikely to anticipate claims 1 or 11 due to its different technical domain (magnetic recording media vs. MTJ for MRAM) and lack of specific disclosure regarding CoFeB, MgO tunnel barriers, or the described manufacturing process.

3. US6379978B2 - Memory cell configuration in which an electrical resistance of a memory element represents an information item and can be influenced by a magnetic field, and method for fabricating it

• Full Citation: US6379978B2.
• Publication/Filing Date: Publication date: April 30, 2002; Priority date: July 15, 1998.
• Brief Description: This patent describes a memory cell configuration and fabrication method where the electrical resistance of a memory element is influenced by a magnetic field. It's a broad patent related to magnetic memory but doesn't specify the material composition of the MTJ layers in the detail of CoFeB and MgO, nor the annealing process to crystallize amorphous layers.
• Potential Anticipation for Claims 1 and 11: This patent broadly covers magnetic memory cells but lacks the specific details of the material layers (amorphous CoFeB, MgO tunnel barrier) and the critical annealing step for crystallization as defined in claims 1 and 11. It might anticipate the general concept of a magnetic memory device, but not the specific manufacturing method.

4. WO2002099905A1 - Tunnel magnetoresistance element

• Full Citation: WO2002099905A1.
• Publication/Filing Date: Publication date: December 12, 2002; Priority date: May 31, 2001.
• Brief Description: This international publication describes a tunnel magnetoresistance element. The abstract for US10680167 mentions that its priority is claimed from PCT/JP2005/004720 filed on March 10, 2005, and Japanese applications 2004-313350 and 2004-071186, filed October 28, 2004 and March 12, 2004, respectively. This WO document is prior to these dates. This document is highly relevant as the assignee is "National Institute Of Advanced Industrial Science And Technology," which is one of the original assignees of US10680167. This suggests a continuation of research.
• Potential Anticipation for Claims 1 and 11: Given the shared assignee and the general nature of a "tunnel magnetoresistance element," this document could potentially disclose aspects of MgO-based tunnel barriers or ferromagnetic electrodes. A detailed review of the full text of WO2002099905A1 would be necessary to determine if it discloses:
  • Amorphous CoFeB layers.
  • An MgO barrier layer that is poly-crystalline with a preferentially oriented (001) crystal plane.
  • An annealing step that crystallizes the CoFeB layers.
    If these specific elements and steps are present, it could directly anticipate claims 1 and 11.

5. JP2002359413A - Ferromagnetic tunnel magnetoresistive element

• Full Citation: JP2002359413A.
• Publication/Filing Date: Publication date: December 13, 2002; Priority date: May 31, 2001.
• Brief Description: This Japanese patent also describes a ferromagnetic tunnel magnetoresistive element, and shares the same priority date as WO2002099905A1. It is also assigned to the "National Institute Of Advanced Industrial & Technology."
• Potential Anticipation for Claims 1 and 11: Similar to WO2002099905A1, this patent is highly likely to be relevant due to the shared assignee and similar subject matter and priority date. A detailed analysis of its content would be crucial to determine if it discloses the specific CoFeB/MgO/CoFeB structure with the described annealing and resulting crystallinity as detailed in claims 1 and 11.

6. US20020191355A1 - Magnetoresistive element and method for producing the same

• Full Citation: US20020191355A1.
• Publication/Filing Date: Publication date: December 19, 2002; Priority date: January 22, 2001.
• Brief Description: This publication describes a magnetoresistive element and its production method.
• Potential Anticipation for Claims 1 and 11: Without reviewing the full text, it is difficult to determine direct anticipation. However, if this document discusses MTJ devices with specific material compositions (like amorphous CoFeB and MgO) and a manufacturing process involving annealing to achieve crystallization and specific crystallinity in the MgO, it could be highly relevant.

7. JP2003086863A - Tunnel magnetoresistive element

• Full Citation: JP2003086863A.
• Publication/Filing Date: Publication date: March 20, 2003; Priority date: September 14, 2001.
• Brief Description: This Japanese patent describes a tunnel magnetoresistive element and is also assigned to "National Institute Of Advanced Industrial & Technology."
• Potential Anticipation for Claims 1 and 11: This patent, again from a shared assignee and concerning tunnel magnetoresistive elements, is highly relevant. A thorough examination of its disclosures regarding specific material stacks (CoFeB, MgO), initial amorphous states, and post-deposition annealing processes is necessary to assess its anticipatory potential for claims 1 and 11.

8. US20030128483A1 - Exchange coupling film, magneto-resistance effect device, magnetic head, and magnetic random access memory

• Full Citation: US20030128483A1.
• Publication/Filing Date: Publication date: July 10, 2003; Priority date: October 12, 2001.
• Brief Description: This publication relates to exchange coupling films, magnetoresistance effect devices, magnetic heads, and MRAM.
• Potential Anticipation for Claims 1 and 11: This document is relevant because it explicitly mentions MRAM and magnetoresistance effect devices. If it details the specific structure and manufacturing steps of an MTJ using amorphous CoFeB, an MgO tunnel barrier, and an annealing process to achieve the claimed crystalline states, it could anticipate claims 1 and 11.

9. US6831312B2 - Amorphous alloys for magnetic devices

• Full Citation: US6831312B2.
• Publication/Filing Date: Publication date: December 14, 2004; Priority date: August 30, 2002.
• Brief Description: This patent, published after the priority date of US10680167 (March 12, 2004) but with a priority date before it, focuses on amorphous alloys for magnetic devices.
• Potential Anticipation for Claims 1 and 11: This patent is highly relevant as it explicitly deals with "amorphous alloys for magnetic devices." If it specifically teaches the use of amorphous CoFeB as ferromagnetic layers in an MTJ, an MgO barrier, and an annealing step that crystallizes the CoFeB while orienting the MgO, it would be a strong anticipatory reference for claims 1 and 11.

10. US20040257719A1 - Magnetoresistive effect element, magnetic memory element magnetic memory device and manufacturing methods thereof

• Full Citation: US20040257719A1.
• Publication/Filing Date: Publication date: December 23, 2004; Priority date: October 12, 2001.
• Brief Description: This publication describes magnetoresistive effect elements, magnetic memory elements, magnetic memory devices, and their manufacturing methods.
• Potential Anticipation for Claims 1 and 11: While published after the priority date of US10680167, its earlier priority date makes it relevant prior art. A detailed examination of this document is needed to determine if it discloses the specific combination of amorphous CoFeB, MgO, and the annealing process to achieve the claimed microstructures.

A comprehensive review of the full text of these and other cited patents is necessary to definitively conclude which claims are anticipated. The focus should be on the exact wording of the claims in US10680167 versus the explicit disclosures in the prior art regarding:

1. The specific materials: CoFeB (amorphous initially), MgO.
2. The layer structure: amorphous CoFeB / MgO / amorphous CoFeB.
3. The manufacturing steps: annealing.
4. The resulting crystallinity: crystallized CoFeB, poly-crystalline MgO with preferentially oriented (001) crystal plane.
5. The timing: all elements must be disclosed in a single prior art reference with a priority date before March 12, 2004, to be considered anticipatory under 35 U.S.C. § 102.

The patent US10680167 has two independent claims, claims 1 and 11, which focus on a method of manufacturing a magnetic tunnel junction (MTJ) device. Both claims involve forming amorphous CoFeB layers as ferromagnetic electrodes, an MgO barrier layer, and then annealing the structure to crystallize the CoFeB layers and achieve a polycrystalline MgO layer with a preferentially oriented (001) crystal plane.

To assess the obviousness of these claims under 35 U.S.C. § 103, we need to consider whether a person having ordinary skill in the art (PHOSITA) at the time of the invention (priority date: March 12, 2004) would have been motivated to combine existing prior art references to arrive at the claimed invention.

Here's an analysis of potential combinations of prior art that could render the claims obvious:

Key elements of the independent claims:

• Amorphous CoFeB ferromagnetic layers: The initial deposition of CoFeB in an amorphous state.
• MgO barrier layer: The use of magnesium oxide as the tunnel barrier.
• Annealing: A post-deposition annealing step.
• Crystallization of CoFeB: The amorphous CoFeB layers crystallizing due to annealing.
• Polycrystalline MgO with (001) preferential orientation: The MgO layer exhibiting this specific crystal structure after the process.

Prior Art References and their relevance:

Many of the cited prior art references generally relate to magnetoresistive elements, magnetic memory devices, or methods of their manufacture. More specific references, and their potential combinations, are discussed below.

1. General Knowledge of MTJs with MgO Barriers and CoFeB Electrodes:

At the time of the patent's priority date, the advantages of MgO as a tunnel barrier for achieving high magnetoresistance in MTJs were well-known, largely due to the work of Shinji Yuasa and others. For example, the patent itself references "Non-Patent Document 1: D. Wang, et al.: Science 294 (2001) 1488," which discusses the use of an amorphous Al-O barrier but sets the stage for improvements. The inventors explicitly state their own theory that "because magnesium oxide is a crystal (where the atoms are arranged in an orderly fashion), as opposed to the conventional amorphous Al—O barrier, the electrons are not scattered and the coherent states of electrons are concerved during the tunneling process." This indicates a general understanding of the benefits of crystalline barriers like MgO.

Similarly, amorphous CoFeB alloys were recognized as promising electrode materials in MTJs due to their high spin polarization and ability to form smooth interfaces with tunnel barriers. Prior art such as US6181537B1, titled "Tunnel junction structure with junction layer embedded in amorphous ferromagnetic layers," indicates the prior existence of amorphous ferromagnetic layers in tunnel junctions.

2. Motivation to Combine MgO and CoFeB, and to Crystallize CoFeB through Annealing:

The motivation to combine MgO as a tunnel barrier with CoFeB as electrodes stems from the desire to achieve high Tunneling Magnetoresistance (TMR) ratios and improved device performance in MRAMs. A PHOSITA would understand that:

• MgO's Crystalline Structure for Coherent Tunneling: The patent explicitly highlights the inventors' theory that a crystalline MgO barrier, particularly with (001) orientation, suppresses electron scattering and preserves coherent electron states during tunneling, leading to very high MR ratios. This was a known theoretical advantage. WO2002099905A1, titled "Tunnel magnetoresistance element," and JP2002359413A, titled "Ferromagnetic tunnel magnetoresistive element," both mention tunnel magnetoresistance elements, and specifically, the latter from the same assignee as the current patent, further indicates research in this direction.
• CoFeB's Amorphous Nature and Subsequent Crystallization: Amorphous CoFeB is known for its magnetic properties and ease of deposition to form smooth layers. The patent itself notes that "an amorphous magnetic alloy" such as CoFeB, FeCoBSi, FeCoBP, FeZr, and CoZr may be used in the electrode layers, and that "an anneal process after the preparation of the MTJ device might cause the amorphous magnetic alloy in the electrode layers to be partially or entirely crystallized, this would not lead to a significant deterioration of the MR ratio. Thus, such a crystallized amorphous magnetic alloy may be used in the electrode layers." This demonstrates that the crystallization of amorphous ferromagnetic alloys, including CoFeB, through annealing was a known technique and its effect on MR ratio was considered. US6831312B2, "Amorphous alloys for magnetic devices," further supports the prior knowledge of amorphous magnetic alloys for devices.
• Annealing to Improve Crystallinity and Interface Quality: Annealing is a standard technique in thin-film deposition to improve crystallinity, reduce defects, and enhance interface properties. For instance, JP2003318465A, "Flattened tunnel magnetoresistive element," refers to the flattening of surfaces, which can be achieved through annealing. A PHOSITA would routinely consider annealing to optimize the properties of the layers, particularly for a crystalline barrier like MgO and for crystallizing amorphous electrodes.

Combination of Prior Art for Obviousness:

Consider the combination of a reference disclosing amorphous CoFeB electrodes (e.g., US6181537B1 or the general knowledge of CoFeB alloys mentioned in US6831312B2) with a reference disclosing MgO tunnel barriers (e.g., WO2002099905A1, JP2002359413A, or other works by Yuasa on MgO barriers). The addition of a conventional annealing step to such a structure would be an obvious optimization.

Furthermore, the patent states that "MgO(001) is initially deposited in a poly-crystalline or amorphous state by sputtering or the like, and then an annealing process is performed such that a poly-crystal in which the (001) crystal plane is preferentially oriented or a single-crystal is obtained." This explicitly details that the process of depositing MgO (possibly in an amorphous or polycrystalline state) and then annealing it to achieve a preferentially (001) oriented polycrystalline or single-crystal MgO layer was a known or at least contemplated method for forming the barrier. This process, when combined with the known use of amorphous CoFeB electrodes and the general practice of annealing to improve material properties, would directly lead to the claimed invention.

Motivation for a PHOSITA:

A PHOSITA would be motivated to combine these elements to overcome the limitations of conventional MTJ devices, such as the low magnetoresistance and poor bias voltage characteristics of amorphous Al-O barriers, as explicitly stated in the background of US10680167. The objective of increasing the output voltage of an MTJ device and providing a memory device with high magnetoresistance for stable operation, as stated in the "Summary of the Invention," would drive a PHOSITA to explore combinations of materials and processing techniques known to enhance these properties.

Specifically, the high predicted MR ratio for coherent spin-polarized tunneling through MgO (001) barriers, when combined with the good magnetic properties and ability to crystallize of CoFeB alloys, would provide a strong motivation for a PHOSITA to combine these materials and employ annealing to achieve the desired crystalline states and interfacial quality. The patent itself reveals that the inventors were aware of the theoretical advantages of crystalline MgO for coherent tunneling and the potential for crystallizing amorphous magnetic alloys in the electrodes through annealing.

Conclusion on Obviousness:

Given the state of the art around the priority date, a PHOSITA would have been motivated to combine:

1. The use of amorphous CoFeB layers as ferromagnetic electrodes.
2. The use of an MgO tunnel barrier, recognizing its potential for high TMR through coherent tunneling (especially with (001) orientation).
3. The application of an annealing step to improve crystallinity and induce the crystallization of amorphous electrode layers.

The patent itself describes these individual concepts and their anticipated benefits within the context of MTJ development. Therefore, the combination of these known elements and processes, driven by the clear objective of improving MTJ performance (higher MR ratio, increased output voltage, stability), would likely render the methods claimed in independent claims 1 and 11 of US10680167 obvious to a PHOSITA at the time of the invention.