US 7084423

I'll search for authoritative information on US 7,084,423, including any 2026 CAFC docket activity.

Let me dig into the litigation history and the actual claim set.

Let me pin down the exact claim language and check for any 2026 appellate activity.

US Patent 7,084,423 B2 — Analyst Summary

Sources used: Google Patents full text of US7084423B2 (which mirrors the USPTO-issued document), PTAB/IPR records for the '423 patent (IPR2020‑01182 and related filings), and the CAFC opinions/orders pages. I did not have direct API access to USPTO Patent Center or PACER, so the docket portion below is based on indexed public mirrors and should be independently verified.

1. Bibliographic data (as literally recorded)

Note on the identifier: this is 7,084,423 — not 7,084,433, 7,084,223, or 7,884,003. The '423 patent is the root application of a large continuation/division family (e.g., 7,462,860; 7,884,003; 8,263,467; 9,425,277; 10,090,395; 11,043,571; 11,355,613, among others). Do not conflate the '423 with those family members, which have different expiry dates and separate IPR histories.

2. Abstract (verbatim)

"An electrical device in which an interface layer is disposed between and in contact with a metal and a Si-based semiconductor, the interface layer being of a thickness effective to depin of the Fermi level of the semiconductor while still permitting current to flow between the metal and the semiconductor. The interface layer may include a layer of a passivating material (e.g., made from nitrogen, oxygen, oxynitride, arsenic, hydrogen and/or fluorine) and sometimes also includes a separation layer. In some cases, the interface layer may be a monolayer of a semiconductor passivating material. The interface layer thickness corresponds to a minimum specific contact resistance of less than or equal to 10 Ω‑μm² or even less than or equal to 1 Ω‑μm² for the electrical device."

3. Technical gist

The patent addresses Fermi‑level pinning at metal–semiconductor contacts. Pinning is attributed to (a) surface/dangling‑bond states and (b) metal‑induced gap states (MIGS) whose electron wavefunctions decay into the semiconductor. The disclosed solution is a thin interface layer — a passivating layer (nitride, oxide, oxynitride, hydride, fluoride, arsenide of silicon) optionally plus a separate separation layer — that simultaneously terminates dangling bonds and displaces the metal far enough to suppress MIGS, while remaining thin enough to permit tunneling/current flow. Claimed performance is expressed as a numerical specific contact resistance (Ω‑μm²). Figures 7a–7d contrast pinned vs. depinned band alignments; FIG. 8 shows the U‑shaped resistance‑vs‑thickness curve that defines the "thin but not too thin" operating window.

4. Independent claims — plain language

The claims are directed to (i) devices/junctions and (ii) a method of making them. The record indicates claim numbering running into the high 70s (the IPR exhibits quote claims 62–78), i.e., roughly 79 claims with many dependents. Exact text is quoted where I retrieved it; where I did not, I paraphrase and flag the paraphrase.

• Claim 1 (electrical device, independent). A metal/interface layer/Si‑based‑semiconductor stack in which the interface layer depins the Fermi level of the metal/conductor in the vicinity of the junction. During prosecution the phrase "Fermi level of the semiconductor" was amended to "Fermi level of the metal/conductor" in claims 1, 19 and 57. (Paraphrase — I did not retrieve verbatim claim 1 text.)
• Claim 19 (method, independent). A method of forming the interface layer on the semiconductor surface (e.g., growth/anneal conditions, temperatures, exposure to nitrogenous material), producing a depinned junction. (Paraphrase; dependent claims 27 etc. recite "grown on the semiconductor surface at temperatures above approximately…")
• Claim 36 (electrical device, independent). A device with a depinned-Fermi-level interface layer, where the device's specific contact resistance is bounded numerically; dependents 39 and 40 recite ≤ ~10 Ω‑μm² and ≤ ~1 Ω‑μm² respectively. (Claim 36 preamble not retrieved verbatim; the numerical dependents are quoted.)
• Claim 41 (independent, quoted): "An electrical device, comprising a junction between a Si-based semiconductor and a conductor separated from the semiconductor by an interface layer having a thickness that allows a Fermi level of the semiconductor to be independent of a Fermi level of the conductor, wherein the electrical device has a specific contact resistance less than approximately 1000 Ω‑μm²." Dependents 42–45 step down through 100, 50, 10 and 1 Ω‑μm².
• Claim 46 (independent, quoted): "An electrical device, comprising: a silicon-based semiconductor of either n-type or p-type semiconductor material; a metal having a workfunction approximately equal to a conduction band of the semiconductor if the semiconductor is of n-type semiconductor material or having a workfunction approximately equal to a valence band of the semiconductor if the semiconductor is of p-type semiconductor material; and an interface layer disposed between and in contact with both the semiconductor and the metal, wherein the electrical device has a specific contact resistance of less than or approximately equal to 1000 Ω‑μm²." Dependents 47–56 add passivating material (nitride, fluoride, oxide, oxynitride, hydride and/or arsenide of silicon), a monolayer, a separation layer, lower resistance bounds, and a nitride formed by heating in nitrogenous material (NH₃, N₂ or unbound N).
• Claim 57 (independent, quoted): "An electrical device, comprising: a silicon-based semiconductor of either n-type or p-type semiconductor material; a metal having a workfunction near or substantially equal to a conduction band edge of the semiconductor if the semiconductor is of p-type semiconductor material, or having a workfunction near or substantially equal to a valence band edge of the semiconductor if the semiconductor is of n-type semiconductor material; and an interface layer disposed between and in contact with both the semiconductor and the metal and configured to depin a Fermi level of the semiconductor." (This is the high‑barrier / high‑voltage family — the metal workfunction is chosen on the opposite band edge from claim 46.)
• Claim 62 (independent). The claim challenged in IPR2020‑01182. It recites a metal, a silicon‑based semiconductor, and an interface layer that is "sufficiently thick to depin a Fermi level of the conductor in the vicinity of the junction … yet thin enough to provide the junction with a specific contact resistance …". Dependents 63, 64 and 66 add passivating material and oxide‑of‑silicon limitations. (Paraphrase from the petition and claim charts; the exact wording of the resistance clause as issued was not fully retrievable.)

Uncertainty flag: I have verbatim text for claims 41, 46, 57 and (from claim charts) 62–66, but only paraphrases for the preambles of claims 1, 19 and 36, and I have not enumerated every independent claim in the 1–79 range. There may be additional independent claims (e.g., further junction claims in the 65–79 range) that I could not confirm belong to the '423 as issued rather than to a continuation‑in‑part (the metal‑oxide/interface‑layer claims in the family are more prominently associated with CIP/continuation filings such as US 2005/0093027 A1 and US 7,176,483). Treat the claim list above as accurate for the claims quoted and provisional for the rest.

5. Litigation / PTAB / CAFC status

• District court: Acorn Semi, LLC v. Samsung Electronics Co., Ltd., No. 2:19‑cv‑00347 (E.D. Tex.) — the family‑wide assertion in which the '423 was among the patents in suit.
• Federal Circuit appeals (patent family):
  • 22‑1499, Acorn Semi, LLC v. [Samsung Electronics Co.](/litigations/by-defendant/Samsung%20Electronics%20Co.), Ltd. — appealed from E.D. Tex. 2:19‑cv‑00347. Voluntarily dismissed with prejudice, Fed. Cir. R. 42(b), order issued 2023‑01‑06 (nonprecedential); mandate issued.
  • 22‑1539, Samsung Electronics Co., Ltd. v. Acorn Semi, LLC — appeal originating from the PTO; order posted 2023‑01‑05 (nonprecedential).
• PTAB: IPR2020‑01182, petitioner Unified Patents (petition filed 2020‑06‑24), challenging claims 62–64 and 66 of the '423 over S.M. Goodnick et al., "Effects of a thin SiO₂ layer on the formation of metal‑silicon contacts," 18 J. Vac. Sci. Technol. (1981), as the primary reference. Google Patents records this proceeding as "Not Instituted – Procedural."
• 2026 CAFC dockets: I found no Federal Circuit docket in 2026 involving US 7,084,423. The only Federal Circuit activity I can verify for this patent is the January 2023 orders in 22‑1499 and 22‑1539. Caveat: my searches covered the CAFC opinions/orders page, Unified Patents litigation portal listings, and general web indexes; CAFC dockets are not exhaustively indexed in free sources, and newly filed or sealed matters may not appear. If a 2026 appeal exists, it would most plausibly arise from a case asserting a later‑expiring family member (e.g., 10,090,395, 11,043,571, 11,355,613) rather than the '423 itself, because the '423 expired 2023‑08‑24 — but I have no evidence of such a 2026 appeal in the material I retrieved.

6. Explicit uncertainties

1. Verbatim text of claim 1, claim 19 (method) and the claim 36 preamble.
2. Total claim count and the complete list of independent claims as issued in the '423.
3. Whether any 2026 CAFC docket exists — negative finding only, not a certified absence.
4. I did not query USPTO Patent Center directly; the bibliographic data above comes from the USPTO‑derived text on Google Patents and should be confirmed against the face of the printed patent and the USPTO assignment database, particularly the current assignee of record (Oak IP, LLC as of 2024‑12‑26).

I'll research litigation involving US 7,084,423. Let me run several searches.

Let me dig deeper into the specific district court and appellate cases.

Let me check for any other defendants/cases involving the '423 patent and confirm details.

Litigation Involving U.S. Patent No. 7,084,423 ("the '423 patent")

Short answer: Based on my searches, there is one known district-court patent infringement action in which U.S. 7,084,423 was asserted — Acorn Semi, LLC v. [Samsung Electronics Co.](/litigations/by-defendant/Samsung%20Electronics%20Co.), et al. (E.D. Tex.) — plus closely related appellate and PTAB proceedings arising out of that same dispute. I found no other lawsuits (e.g., against Micron, Intel, TSMC, or others) asserting the '423 patent. I could not independently access the Darts-ip "global patent litigation dataset" link shown on the Google Patents page, so my list is limited to what the public sources returned.

⚠️ Note on search hygiene: some results concerned a different patent (a "442 patent" asserted by Realtime Adaptive Streaming, and Realtime's various cases). Those are not U.S. 7,084,423 and I have excluded them.

1. District Court Litigation

Outcome / current status

• Claim construction (Oct. 16, 2020): The magistrate judge's Claim Construction Memorandum Opinion and Order (Dkt. 85) found a term of claim 62 of the '423 patent indefinite. District Judge Gilstrap adopted the recommendation in full on December 10, 2020. Because the asserted claims of the '423 patent all depend from claim 62, the '423 patent's asserted claims were effectively removed from the case (and were not submitted to the jury in the final verdict form, which listed only the '336, '167, '691, and '395 patents).
• Jury verdict (May 19, 2021): The jury found Samsung infringed the tried claims (of the '336, '167, '691, and '395 patents) and awarded Acorn $25 million in damages. (The '423 patent was not part of the verdict.)
• Attorneys' fees: Acorn's motion for fees under 35 U.S.C. § 285 was denied (Dkt. 409, Feb. 17, 2022) — the court found neither party blameless in the discovery disputes.
• Appeal: Samsung appealed to the Federal Circuit (see §3 below), and the appeal was ultimately voluntarily dismissed with prejudice on January 6, 2023, with each side bearing its own costs and fees — indicating the dispute was resolved/settled post-trial.
• Current status: Terminated (case closed; appeal dismissed).

2. Related PTAB Proceeding (administrative — not "litigation" in the district-court sense)

(Note: One petition document cites the number as "IPR2019-01182," but the petition, PTAB docket, and Google Patents all identify the proceeding as IPR2020-01182. I am flagging this as an apparent typo in that document rather than auto-correcting the record.)

3. Federal Circuit Appeal

Companion appeals (different patents, same family): Samsung also appealed four PTAB IPR decisions in related appeals Nos. 2022-1539, 2022-1540, 2022-1541, and 2022-1542 (Samsung Electronics Co., Ltd. v. Acorn Semi, LLC, from IPR2020-01206, -01207, -01279, -01282). Those concerned the '691 and '395 patents, not the '423 patent.

Summary Table

Caveats / Confidence

• High confidence in the Samsung/E.D. Tex. case, the '423 claim indefiniteness ruling, the $25M verdict, the IPR2020-01182 denial, and the 22-1499 dismissal — all corroborated by court/PTAB documents and the Google Patents litigation links.
• No other defendants suing or being sued on the '423 patent were found in my searches. This is a negative finding, not a guarantee; the Google Patents page references a Darts-ip "family litigation" dataset (family 31495225) that I could not open, so additional family-level suits (on sibling patents) could exist that do not name the '423 patent itself.
• If you need a definitive litigation history, the authoritative sources would be the case dockets on PACER for E.D. Tex. 2:19-cv-00347, the CAFC docket for 22-1499, and the Darts-ip family record.

I'll verify the AIA trial history against the structured data block and resolve the conflicting petitioner attributions in the prior sections.

Critical discrepancy found: the petitioner was Samsung, not Unified Patents. Let me verify the remaining details.

Let me pin down the panel, the exact challenged claims, and rule out a second (Unified Patents) petition.

⚠️ Threshold data conflict — read first

The structured "PTAB proceedings on file" block in this prompt reports no AIA trial proceedings for US 7,084,423 on the USPTO Open Data Portal. That negative is not correct. Live web results decisively establish that a real IPR was filed against this exact patent (U.S. 7,084,423, App. 10/217,758): IPR2020-01182. I am reporting the proceeding, not the null result, and flagging the conflict rather than silently resolving it — per your instruction to surface (not suppress) proceedings the ODP list omits.

Two further corrections to the previously generated sections, which I am not repeating but must cross-reference:

Proceedings overview

One AIA trial proceeding exists on US 7,084,423 — IPR2020-01182 — and it terminated at the institution stage: 0 proceedings active, 0 claims invalidated, 0 claims sustained, 0 settled, 1 institution denied. The bottom line for a defendant is unusual and cuts both ways: because no IPR was ever instituted, no claim of the '423 patent has ever been adjudicated on the merits at the PTAB, which means (a) there are no cancelled claims for you to point to, but equally (b) no § 315(e)(2) estoppel attached, so the Goodnick-based prior art remains fully available to you in district court — and the patent has been expired since 2023-08-24, leaving only a pre-expiration damages tail.

IPR2020-01182 — [Samsung Electronics Co., Ltd. et al.](/litigations/by-plaintiff/Samsung%20Electronics%20Co.%2C%20Ltd.%20et%20al.) v. Acorn Semi, LLC

• Type: Inter Partes Review (35 U.S.C. §§ 311–319)
• Filed: 2020-06-24
• Status: Institution Denied (USPTO ODP would say "Not Instituted"; Google Patents renders it "Not Instituted – Procedural"). No trial, no FWD.
• Patent: U.S. 7,084,423 B2 (App. 10/217,758)
• Judge panel: Not retrieved. The panel of APJs on Paper 17 (2021-02-10) is not named in any source I could reach. Flagged as unknown rather than guessed. The decision should be obtainable from the PTAB E2E docket: https://ptacts.uspto.gov/ptacts/ (case IPR2020-01182) or the mirrors at https://www.docketalarm.com/cases/PTAB/IPR2020-01182/Inter_Partes_Review_of_U.S._Pat._7084423/ and https://ipverse.greyb.com/ptab-web/cases/case-details/IPR2020-01182
• Petition grounds: Challenged claims 62–64 and 65 (see discrepancy note), on § 102/§ 103 grounds built on S.M. Goodnick et al., "Effects of a thin SiO₂ layer on the formation of metal-silicon contacts," 18 J. Vac. Sci. Technol. (1981) as the primary reference. ⚠️ Secondary-source based. I confirmed Samsung's petition and Dr. E. Fred Schubert's declaration exist (Petition, 2020-06-24, 76 pp.; Schubert Decl., 2020-06-23, 139 pp.) but did not retrieve the verbatim Ground table, so I will not assign challenge-by-challenge statutory labels.
• Institution decision: Denied — 2021-02-10 (Paper 17), discretionary denial under 35 U.S.C. § 314(a). The Board's reasoning: the parallel E.D. Tex. case had already held claim 62 indefinite (magistrate judge, 2020-10-16; adopted in full by Judge Gilstrap, 2020-12-10), and every challenged claim depends directly or indirectly from claim 62. The Board refused to let Samsung simply outrun that ruling: "We do not agree that Petitioner may properly approach this issue by simply asserting that, for this proceeding, whatever this phrase means, it is shown in the prior art." Because Samsung "ha[d] not set forth any explanation of how we could address the limitation at issue consistently with the indefiniteness arguments Petitioner successfully advanced in the litigation," institution "would not be in the interests of justice or efficiency." (Quoted from Paper 17 at 7 via the PTAB Litigation Blog: https://www.ptablitigationblog.com/district-court-indefiniteness-ruling-leads-to-denial/)
• Fintiv / Sotera stipulation: After the Board's Paper 15 inquiry, Samsung agreed (2020-12-23 filing) to a Sotera-style stipulation covering all ten of its Acorn IPRs: "In the event one or more of these Petitions is granted on a given patent, Petitioner will not pursue in the Acorn Litigation any invalidity ground on that patent that was raised or that could have been reasonably raised in an IPR." Samsung itself acknowledged the stipulation "may be moot" for IPR2020-01182, and Acorn argued the Board "should not waste its valuable time" on it. Note the condition precedent — "in the event … is granted" — was never satisfied for the '423.
• Final Written Decision: None. No FWD issued, because no trial was instituted. No claim of the '423 patent was cancelled, confirmed, or otherwise adjudicated on the merits.
• Settlement / termination: This proceeding was not settled — it was decided (denied). The underlying litigation (E.D. Tex. 2:19-cv-00347) and its appeal (Fed. Cir. 22-1499) were resolved by voluntary dismissal with prejudice on 2023-01-06, consistent with a confidential settlement. The terms are not public — do not assume any patent-specific license or covenant.
• Appeal: None, and none was legally available. A denial of institution is "final and nonappealable" under § 314(d). There is no Federal Circuit docket for IPR2020-01182. (This is consistent with the prior sections' negative 2026-CAFC finding — and it explains why the '423 has no appellate history on the merits.)
• Defensive value: Modest but real. The institution denial was not a merits win for Acorn — it was a housekeeping denial driven by the district court's indefiniteness ruling, and it carries no claim-level res judicata and triggers no IPR estoppel. But a defendant cannot use this proceeding as an invalidity roadmap, because the Board never reached the art. The real leverage is the E.D. Tex. indefiniteness holding on claim 62, which was never reviewed on appeal (the appeal was dismissed) and is therefore persuasive, not binding, authority.

Claim-number discrepancy (unresolved). The PTAB Litigation Blog states Samsung challenged claims 62–64 and 65. The prior litigation section (from the district court's preliminary invalidity contentions) lists the asserted claims as 62–64 and 66. If both readings are right, the petitioner attacked 65, which was not asserted, and left 66, which was asserted, unchallenged — a mismatch that, had the IPR been instituted, could have left part of the case standing. I could not retrieve the Petition's Ground table to settle this. Verify against Paper 2 of IPR2020-01182 before relying on either number.

Numbering anomaly preserved, not corrected. Acorn's own Mandatory Notice in this case is captioned "Case IPR2019-01182," while the Board's caption, the petition, and every docket mirror read IPR2020-01182. Per your operating rules I am recording the identifier literally and treating IPR2020-01182 as the proceeding number, consistent with the prior sections' flag.

Strategic summary

Claim status on 7,084,423: CANCELED — none. SUSTAINED — none. UNTESTED — all of them. No claim of this patent has ever been construed, instituted on, or decided by the PTAB. The only claim-scope adjudication in the record is the E.D. Tex. indefiniteness holding on claim 62 (and thus its dependents), handed down 2020-12-10 and never reviewed on appeal because the appeal was dismissed with prejudice. Any statement that the '423 "survived an IPR" or "was narrowed in an IPR" is wrong on this record — nothing was survived and nothing was narrowed, because nothing was tried. Equally, no one can tell you a claim is dead.

Estoppel landscape. This is the most consequential point for a defendant and it is favorable. Section 315(e)(2) estoppel attaches only to a "petitioner in an inter partes review that results in a final written decision under section 318(a)." IPR2020-01182 produced no FWD, so no statutory estoppel arose — not for Samsung, and not for any privy or real party in interest. The Sotera stipulation Samsung signed was expressly conditioned on institution ("In the event one or more of these Petitions is granted…"), so it never bound Samsung as to the '423 either. Practically, this means the Goodnick 1981 reference and every § 102/§ 103 ground Samsung raised — or reasonably could have raised — remain available to a later defendant in district court on this patent. Two caveats: (i) the ordinary § 315(b) one-year bar still runs from service of a complaint against you, and (ii) because the '423 expired 2023-08-24, IPR now serves only to knock out the pre-expiration damages tail (§ 286's six-year lookback reaches back to roughly 2020-09-30), not to defeat an ongoing royalty or injunction.

Pattern signals. No defensive aggregator ever filed against the '423 — the only petitioner is Samsung, and its one petition was part of a coordinated ten-petition, six-patent campaign against the Acorn family (siblings included IPR2020-01183 on the '261 patent and the "Goodnick" IPRs IPR2020-01279/-01282 on the '691 and '395 patents). On the sibling patents, the Board went the other way and instituted; the FWDs there credited Acorn and found Samsung's motivation-to-combine arguments unconvincing, with the Board reasoning that Samsung had failed to prove its resistance-reduction assertion, that one reference taught away, and that another did not support the proposed layered structure — and those FWDs were appealed to the Federal Circuit (Nos. 2022-1539 to -1542) before the 2023-01-06 dismissal disposition. Do not read those sibling outcomes as precedent about the '423 — different claims (titanium-oxide spacer limitations), different specification support, no FWD here. Patent owner Acorn Semi never had to defend a PTAB appeal on the '423 because it never had one.

Family-level signal you should not miss. IPR2025-01129 (GlobalFoundries v. Oak IP, LLC) targets U.S. 10,937,880 — a family member claiming priority through the '423 — and the petition attacks the "oxide of titanium" limitations on written-description/priority grounds (arguing they are not entitled to the 2002 priority date). Oak IP, LLC is the current assignee of record of the '423 (assignment recorded 2024-12-26). If a demand letter today cites this family, it is far more likely to cite a later-expiring member ('880, '395, '571, '613) than the expired '423. (Current family-level art).

Institution-law context. The § 314(a) rationale in IPR2020-01182 is now historical. The Office rescinded the Vidal-era Fintiv memorandum on 2025-02-28, and as of 2026 the Director has taken over institution decisions with summary notices — the Fintiv factors are not currently being applied as before. A Fintiv-style denial of the kind Acorn won in 2021 is materially less likely today. Note also the pending Supreme Court petition in Intel v. Squires, No. 26-73 (petition filed 2026-07-13, with Samsung as an amicus) seeking review of the Federal Circuit's holding that PTO institution standards are unreviewable under § 314(d). That case is about reviewability of institution rules, not about this patent.

Recommended next steps

1. Pull Paper 2 and Paper 17 of IPR2020-01182 from PTAB E2E (https://ptacts.uspto.gov/ptacts/) to (a) fix the challenged-claim list at 62–64/+65 vs. +66, (b) obtain the APJ panel names, and (c) capture the Ground table verbatim. Both are currently flagged as unretrieved.
2. If you are a defendant and a demand cites the '423: quote E.D. Tex. 2:19-cv-00347's indefiniteness holding on claim 62 and its dependents (magistrate, 2020-10-16; adopted 2020-12-10) and note that the asserted claims were withdrawn from the verdict form — while acknowledging the ruling is unreviewed and non-binding outside that case.
3. Do not assert IPR estoppel against yourself — and do not assume it against Acorn/Oak. There is none on this patent. Treat Goodnick 1981 and the Samsung petition as freely reusable art and argument.
4. Calendar the expiry, not the trial. The '423 expired 2023-08-24; damages exposure is limited to activity before that date within § 286's lookback from filing. Any real 2026 litigation value in this family sits in the unexpired continuations, which have their own separate and materially different PTAB histories.

Confidence: High on the existence, petitioner, filing date, denial date, § 314(a) rationale, absence of FWD, and absence of appeal. Medium on the challenged-claim set (unresolved 65/66 conflict) and on the identity of the primary reference as Goodnick (secondary-source based, though Samsung's petition and Schubert declaration are confirmed on the docket). Unknown — expressly not guessed — the APJ panel for Paper 17.

I'll research the assignment chain, correspondent attorneys, and entity details before writing. Let me run parallel searches.

Excellent — this surfaced major new findings (Acorn→Oak IP/Dominion Harbor, Peter Norton). Let me pin down reel/frame numbers, correspondence, and Oak IP's identity.

⚠️ Sourcing note before the required sections. The authoritative text supplied for this patent (Google Patents full text of US7084423B2) exposes legal events — conveyance type, assignor, assignee, and a single date per event — but it does not expose reel/frame numbers or the correspondent of record. USPTO Assignment Center (assignmentcenter.uspto.gov) could not be queried directly from this environment (it is a JavaScript app), and my searches did not surface the abstract-of-title page for this patent. I will therefore not invent reel/frame numbers or correspondent names; where those fields are unavailable I mark them "not retrieved" and explain. This is a genuine gap, not an absence of assignments — there are six recorded events.

⚠️ Contradiction flagged with a previously generated section. The earlier Patent summary (¶5) states the IPR2020‑01182 petitioner was "Unified Patents." The earlier Litigation summary (§2) correctly states it was Samsung Electronics Co., Ltd. The PTAB filings themselves are captioned "SAMSUNG ELECTRONICS CO., LTD., Petitioner v. ACORN SEMI, LLC, Patent Owner" (Docket Alarm doc headers); Lexology and GreyB corroborate. Samsung is correct; the "Unified Patents" attribution in the Patent summary is wrong. A secondary discrepancy: the Patent summary lists the IPR as challenging claims 62–64 and 66, whereas Lexology reports the IPR challenged 62–64 and 65; the district-court infringement/invalidity contentions covered 62–64 and 66. Both numbers appear in the record for different proceedings.

Inventors

Unusual‑pattern check. The "all inventors depart within 12 months of filing" fire‑sale precursor is not present. Grupp appears as first‑named inventor ("Grupp et al.") on Acorn continuation filings as late as 2016–2020, and Acorn's own press release (June 2021) lauds "Dr. Dan Grupp and Dr. Dan Connelly" as the inventors. The inventors stayed attached to the original assignee across the entire prosecution family. What is notable is the opposite: the family was kept alive by the same two inventors for ~18 years and monetized through continuations.

Original assignee

Acorn Technologies, Inc. (La Jolla, CA) — named on the face of the issued patent via the 2002‑08‑12 assignment.

• Line of business: Describes itself as "a product‑oriented company … providing ground‑breaking innovations for the semiconductor and telecom markets since 1998," delivering "IP cores, algorithms, processes, and products" through subsidiaries Acorn Semi (semiconductor/Fermi‑level‑depinning patents) and PHY Wireless (wireless/IoT). Its chairman is Peter Norton (Norton Utilities/antivirus fame); its CEO is Tom Horgan (per the June 3, 2021 press release).
• Did it ship a product embodying the claims? Unclear/partially. Acorn characterizes itself as product‑oriented and licenses IP cores and algorithms, but I found no evidence of a commercial silicon product embodying the '423 claims. Its monetization of this family ran through litigation (see below), not through a product line.
• Current status: Operating / not dissolved. As of the 2024‑12‑26 recordings, Acorn Technologies, Inc. and Acorn Semi, LLC both received releases (i.e., they were still existing entities of record). Acorn Semi appears to have continued prosecuting new applications (third‑party records show Acorn Semi filings into 2025–2026). No bankruptcy filing is evidenced anywhere in the record.

Important structural note: Acorn Semi, LLC is a wholly owned subsidiary of Acorn Technologies Inc. (stated in Acorn's own June 2021 press release). So the 2019 transfer below is a parent→subsidiary move, not an arm's‑length sale.

Assignment timeline

Reel/frame and correspondent could not be retrieved for any entry — see the sourcing note above. Dates below are the single dates Google Patents records per event; I cannot separate "executed" from "recorded" from this source, and I flag the one sequence anomaly explicitly.

• 2002‑08‑12 (executed) / recorded 2002‑08‑12 — Reel not retrieved

  • Conveyance: Assignment of assignors' interest ("ASSIGNMENT OF ASSIGNORS INTEREST (SEE DOCUMENT FOR DETAILS)")
  • Assignor: Daniel E. Grupp; Daniel J. Connelly
  • Assignee: Acorn Technologies, Inc. (La Jolla, CA)
  • Correspondent: not retrieved
  • Context: Original acquisition — inventors' obligation‑to‑assign to their own company, perfected on the filing date.

• 2019‑05‑30 — Reel not retrieved

  • Conveyance: Security Interest ("SECURITY INTEREST (SEE DOCUMENT FOR DETAILS)")
  • Assignor: Acorn Semi, LLC
  • Assignee: The Peter Norton Living Trust dated April 28, 1989
  • Correspondent: not retrieved
  • Context: Securitization — a related‑party collateral grant to a trust of Acorn's own chairman (Peter Norton), secured against the patent portfolio.
  • ⚠️ Sequence anomaly: the security interest (2019‑05‑30) is recorded before the assignment that put the '423 into Acorn Semi (2019‑06‑26). This is consistent with a portfolio‑wide security agreement covering "all patents now or hereafter acquired," or with Acorn Semi already holding the family under an earlier (unrecorded here) transfer. Either way, the grantor‑before‑grantee ordering is a flag for anyone tracing title.

• 2019‑06‑26 — Reel not retrieved

  • Conveyance: Assignment of assignors' interest ("ASSIGNMENT OF ASSIGNORS INTEREST (SEE DOCUMENT FOR DETAILS)")
  • Assignor: Acorn Technologies, Inc.
  • Assignee: Acorn Semi, LLC
  • Correspondent: not retrieved
  • Context: Internal reorg / creation of a litigation‑holding subsidiary — executed ~4 months before the Oct 23, 2019 Samsung complaint (see signal 5).

• 2024‑12‑26 — Reel not retrieved (release #1)

  • Conveyance: Release by Secured Party ("RELEASE BY SECURED PARTY")
  • Assignor: The Peter Norton Living Trust (as secured party)
  • Assignee: Acorn Technologies, Inc.
  • Correspondent: not retrieved
  • Context: Collateral release — clearing the 2019 security interest in connection with the portfolio sale.

• 2024‑12‑26 — Reel not retrieved (release #2)

  • Conveyance: Release by Secured Party
  • Assignor: The Peter Norton Living Trust (as secured party)
  • Assignee: Acorn Semi, LLC
  • Correspondent: not retrieved
  • Context: Collateral release — same transaction, second named obligor.

• 2024‑12‑26 — Reel not retrieved (the transfer that matters)

  • Conveyance: Assignment of assignors' interest ("ASSIGNMENT OF ASSIGNORS INTEREST (SEE DOCUMENT FOR DETAILS)")
  • Assignor: Acorn Semi, LLC
  • Assignee: Oak IP, LLC
  • Correspondent: not retrieved
  • Context: Transfer‑to‑asserter / monetization exit. Oak IP is a Dominion Harbor affiliate (see signal 2). This is one of ~36 patents moved in the same December 2024 transaction; the two same‑day releases were cleanup to deliver clean title.

One‑paragraph adjacency note (not a finding on the '423 chain): my searches surfaced the Orange/France Telecom → Transpacific → Acacia → Monarch chain and its repeat correspondent "S. Kareff c/o Schulte Roth & Zabel LLP" (e.g., reel 052853/0153; reel 055101/0608). That chain belongs to a different patent family (App. 12/528,083, Jounay et al.) and must not be attributed to the '423. I mention it only because it is a textbook illustration of the repeat‑correspondent tell this task asks about and could be confused with Acorn's chain on a careless read.

Timeline diagram

timeline
    title Ownership of US 7084423
    2002 : Filed by Grupp and Connelly
         : Assigned to Acorn Technologies
    2006 : Patent issued
    2019 : Security interest to Peter Norton Trust
         : Assigned to Acorn Semi LLC
         : Samsung suit filed
    2021 : Jury awards 25M on sibling patents
    2024 : Security interest released
         : Assigned to Oak IP LLC
    2025 : Oak IP sues GlobalFoundries

NPE / troll-pattern signals

1. Shell-entity transfer — PRESENT.
The patent moved from an operating/licensing parent (Acorn Technologies, acting through its wholly owned subsidiary Acorn Semi) to Oak IP, LLC, which per Oak IP's own PTAB mandatory notice (IPR2025‑01129, dated June 13, 2025) is "a wholly‑owned subsidiary of Monument Patent Holdings, LLC, which is a wholly‑owned subsidiary of Dominion Harbor Enterprises, LLC." Oak IP's stated place of business is 812 W. McDermott Dr. #1026, Allen, TX 75013 — a numbered‑box address consistent with a registered‑agent/mail‑drop footprint, and a Texas LLC. Oak IP ships no products; its only visible activity is assertion. Cites: 2024‑12‑26 assignment entry; IPR2025‑01129 mandatory notice; Oak IP, LLC v. GlobalFoundries (D. Del. 1:25‑cv‑00142, filed 2025‑02‑04). Strong.

2. Known asserter in the chain — PRESENT.
Oak IP is not on the enumerated list (Acacia, Marathon, IV, IPNav, Wi‑LAN, Mosaid/Conversant, Vringo, Pendrell, Innovatio, MPHJ, Lumen View, Round Rock, Document Generation, Spangenberg entities), so I will not overstate it. But its ultimate parent, Dominion Harbor Enterprises, LLC, is a well‑documented high‑frequency patent monetization/assertion enterprise, and Oak IP is its litigation front. Independent third‑party coverage (GreyB, "December's Patent Transfers Signal Higher NPE Risks for Semiconductors") expressly frames the Oak IP acquisition as an NPE‑risk event and notes the GlobalFoundries suit followed the December 2024 purchase. Cites: IPR2025‑01129; IPR2025‑01052; GreyB. Strong, with the caveat that the specific name "Oak IP/Dominion Harbor" is outside the enumerated list.

3. Repeat correspondent across the chain — UNCLEAR (data gap).
I could not retrieve any correspondent-of-record entry for this patent from Assignment Center or an abstract-of-title mirror, so I cannot test recurrence. Do not treat this as a negative finding — it is a retrieval failure. Two leads (not findings, and not assignment correspondents): (a) Acorn's later‑family prosecution correspondence ran through Ascenda Law Group, PC (Tarek Fahmi; patents@ascendalaw.com), visible in the '593 prosecution history; (b) Acorn's PTAB counsel is Matthew C. Phillips, Reg. No. 43,403 (signature on Acorn's mandatory notices). Neither is an assignment‑recordation correspondent, and I have not tied either to the 2024 Oak IP recording.

4. Cascading transfers — NOT PRESENT (as defined).
The chain is two substantive transfers across ~5 years (Acorn Tech → Acorn Semi in 2019; Acorn Semi → Oak IP in 2024), not a rapid multi‑LLC cascade in under 24 months. However, note the structural tell that is here: three recordings clustered on a single day, 2024‑12‑26 (two releases + one assignment), the signature of one closing package prepared by one party — commonly one law firm/correspondent across all three. Worth confirming once the correspondents are pulled.

5. Pre‑litigation transfer — PRESENT.
The assignment moving the '423 from Acorn Technologies to Acorn Semi, LLC is dated 2019‑06‑26; the first infringement suit naming the '423 (Acorn Semi, LLC v. Samsung Electronics Co., Ltd., E.D. Tex. 2:19‑cv‑00347) was filed 2019‑10‑23 — ~4 months later, inside the 6‑month window. This is the classic "assign to a clean holding/litigation subsidiary before suing" move (it also creates standing for the entity that actually sues). The Peter Norton Trust security interest (2019‑05‑30) lands ~5 months before suit as well. Cites: 2019‑06‑26 and 2019‑05‑30 entries; Dkt. No. 1 in 2:19‑cv‑00347. Strong.

6. Bankruptcy fire‑sale — NOT PRESENT.
No Chapter 7/11 proceeding is evidenced for Acorn Technologies, Acorn Semi, or Oak IP in anything I retrieved, and Acorn publicly announced a trial win in June 2021 and continued filing applications afterward. The 2024 transfer reads as a negotiated monetization exit, not an insolvency liquidation.

7. Privateering — NOT PRESENT / UNCLEAR.
Classic privateering is a third‑party operating company handing patents to an NPE to sue its competitors. Here the original assignee (Acorn) is itself the technology developer and the entity that first sued, then sold out to Dominion Harbor. That is a monetization exit, not privateering by a distinct operating sponsor. Not present.

8. Defensive aggregator — NOT PRESENT.
The chain terminates at Oak IP, LLC (an active asserter), not RPX, AST, LOT Network, Unified Patents, or OIN. The patent is not neutralized; it (with its family) was asserted against GlobalFoundries on 2025‑02‑04.

Verdict

NPE — high confidence.

The chain ends at Oak IP, LLC via the 2024‑12‑26 assignment from Acorn Semi, LLC, and Oak IP's own PTAB filing (IPR2025‑01129, June 13, 2025) confirms it is a wholly owned subsidiary of Monument Patent Holdings, LLC → Dominion Harbor Enterprises, LLC, operating from a numbered‑box Texas address with no products — a textbook shell/asserter (signal 1). That purchase was purpose‑built for assertion: Oak IP filed suit against GlobalFoundries on 2025‑02‑04, and the same portfolio had already been validated by the $25M Samsung jury verdict, while the family's pre‑suit history shows the tell‑tale 2019‑06‑26 transfer into a litigation subsidiary roughly four months before the 2019‑10‑23 Samsung complaint (signal 5). Two‑plus strong signals → high confidence, with the caveats that (a) the predecessor owner, Acorn, was a genuine technology developer whose 2019 assertion against Samsung had operating‑company characteristics, and (b) I could not retrieve correspondents, so the repeat‑correspondent tell is untested rather than absent.

Verify at: https://assignment.uspto.gov/patent/index.html (search patent number 7084423) or https://assignmentcenter.uspto.gov/ — pull the abstract of title to obtain the reel/frame and correspondent fields this analysis could not retrieve, and to confirm whether the 2024‑12‑26 recordings share one correspondent/firm.

I'll research the prior art cited against US 7,084,423. Let me run several searches.

Let me get the specific prior-art citation list for the '423 patent itself (not its family members).

Let me retrieve the front-page "References Cited" of the '423 patent itself.

I was unable to retrieve the OCR'd front page of US 7,084,423 B2 directly within my tool-step budget, so the citation lists below come from the "References Cited" columns of '423-family front pages (US 7,884,003; 7,176,483; 9,461,167; 11,043,571; 11,056,569) and from the IPR2020‑01182 petition papers. I flag confidence per item. I did not auto-correct any number.

Prior art for US 7,084,423 B2 ("the '423")

Effective filing / priority date: 2002‑08‑12 (application 10/217,758). Because this is a pre‑AIA patent, cited art is relevant under § 102(a)/(b)/(e) as it existed then (novelty date 2002‑08‑12; one‑year bar 2001‑08‑12).

0. Two threshold findings that shape everything below

1. The claims that were later attacked had no cited prior art. The IPR2020‑01182 petition states expressly: "the Examiner did not cite any prior art against Claims 62–64 and 66 during prosecution." So the art discussed in § 4 below is newly‑asserted art, not "patent citations" of the '423.
2. A reference on the face of a patent is not automatically an anticipation reference. Most of the items in the "References Cited" column were cited as background or applied under § 103 (obviousness), often in combination. Anticipation under § 102 requires a single reference disclosing every element arranged as claimed. My § 102 assessments below are therefore potential, not record findings — I do not have the Office actions.

1. U.S. patent documents cited (family citation set)

Confidence: high that these numbers/assignees/dates are the '423‑family cited set; medium that every one appears on the '423's own face (some may be additions made during the later CIP/continuation prosecutions). Flagging accordingly.

2. Foreign patent documents cited (family set)

(WO 2004/015782 and WO 2004/030104 are the Acorn/PCT family publications noted on the Google Patents family timeline; as applicant's own later‑published cases they are not § 102 art against the 2002 priority.)

3. Non‑patent literature cited (selected, most relevant first)

Long list; the most technically on‑point items:

• S.M. Sze, "Metal–Semiconductor Contacts," in Physics of Semiconductor Devices, Wiley (1981) — the canonical Schottky‑barrier text; § 102/§ 103 background for the barrier‑height concepts.
• M.A. Sobolewski & C.R. Helms, "Studies of barrier height mechanisms in metal–silicon nitride–silicon Schottky barrier diodes," J. Vac. Sci. Technol. (Jul/Aug 1989), pp. 971‑979 — metal / Si₃N₄ / Si Schottky diodes with tunable barrier height. Strong § 102 candidate for the nitride‑interface‑layer claims (41, 46/47, 62‑66).
• M.A. Sobolewski et al., "Properties of Ultrathin Thermal Nitrides in Silicon Schottky Barrier Structures," Appl. Phys. Lett. 54(7) (Feb 13, 1989), pp. 638‑640 — ultrathin nitride at an Si Schottky barrier.
• H.C. Card & E.H. Rhoderick, "Studies of tunnel MOS diodes I: Interface effects in silicon Schottky diodes," J. Phys. D 4 (1971), pp. 1589‑1601 — thin interfacial oxide controlling effective barrier; § 102/§ 103.
• M.O. Aboelfotoh, "Influence of thin interfacial silicon oxide layers on the Schottky‑barrier behavior of Ti on Si(100)," Phys. Rev. B 39(8) (Mar 15, 1989), pp. 5070‑5078 — thin oxide interface layer modifies Schottky barrier: directly on point for the "interface layer" limitations.
• A. Thanailakis & R.C. Northrop, "Transition‑metal contacts to atomically clean silicon," J. Phys. C 9 (1976) — barrier‑height vs. metal.
• M.A. Taubenblatt & C.R. Helms, "Interface effects in titanium and hafnium Schottky barriers on silicon," Appl. Phys. Lett. 44 (May 1, 1984), pp. 895‑897 — interfacial‑layer effects on barrier height.
• C.Y. Chang et al., "Specific contact resistance of metal–semiconductor barriers," Solid‑State Electronics 15 (1971), p. 541 — the Ω·cm²/Ω·μm² specific‑contact‑resistance metric underpinning the numerical claim limitations.
• E.H. Rhoderick, "Metal–semiconductor contacts," IEE Proc. 129 (Feb 1982) — review of barrier formation.
• J. Tersoff, "Schottky Barrier Heights and the Continuum of Gap States," Phys. Rev. Lett. 52(6) (Feb 6, 1984) — the MIGS model relied on throughout the '423 spec.
• V. Heine, Phys. Rev. Lett. 138(6A) (1965); Louie, Chelikowsky & Cohen, "Ionicity and the theory of Schottky barriers," Phys. Rev. B 15, 2154 (1977) — MIGS theory.
• E. Yablonovitch et al., "Unusually Low Surface‑Recombination Velocity on Silicon and Germanium Surfaces," Phys. Rev. Lett. 57(2) (1986) — surface passivation.
• D.J. Chadi et al., "Fermi‑Level‑Pinning Defects in Highly n‑Doped Silicon," Phys. Rev. Lett. 79(24) (1997).
• L.M. Porter & R.F. Davis, "A critical review of ohmic and rectifying contacts for silicon carbide," Mater. Sci. Eng. B 34(2) (Nov 1995).
• Weinberger et al., "Surface chemistry of HF passivation of silicon…" J. Appl. Phys. 60(9) (1986); Y. Hayafuji et al., "Nitridation of silicon and oxidized silicon," J. Electrochem. Soc. (Sep 1982) — the HF‑passivation and nitridation methods.
• Bauernschmitt et al., "Yb–SiO₂–Si Tunneling Junctions," Elsevier (1993) — tunneling through an interfacial oxide.
• Plus the remaining ~40 NPL items (Aberle, Blosse, Chen, Connelly, Gopalakrishnan, Hasegawa, Huang, Hilsenbeck, Kamiyama, Kedzierski, Kimura, Cai, Lee, Miyawak, Mandelis, Noshioka, Okamoto, McKee, Bringans, De Almeida, Tung, Hara×3, Verhacebeke, Wolf, Schmidt, Shaik, Snyder, Kamins, Teraji, Thompson, Baumvol, Spicer, Wang, Wei, Widjaja, Wright, Yagishita, Yang, Efthimios/Kaxiras, Tao×2, Udeshi, Zhu×2, Patel, Nauka, Gilmer, Akers, Edelstein, Padovani, J.R. Patel, Shalish, Izumi, etc.) — mostly background/§ 103.

4. The art actually asserted against claims 62–64 and 66 (IPR2020‑01182)

This is the only art I can confirm was substantively applied against the '423's claims, and it was new art not on the patent's face:

Outcome: IPR2020‑01182 was not instituted (per Google Patents, "Not Instituted – Procedural"; the earlier litigation summary reports denial on § 314(a) discretion tied to the parallel district court's finding that claim 62 was indefinite). This matters for § 102 analysis: none of this art was ever adjudicated to anticipate or render obvious the challenged claims.

5. Which references are the most relevant for § 102 purposes (ranked)

1. US 3,983,264 (Schroen) — single‑reference candidate for the core metal/interface‑layer/semiconductor junction idea (claims 1, 36, 41, 46, 57, 62). If it shows a deliberately thin interfacial layer chosen to tune barrier height while passing current, it is the closest thing to an anticipatory reference.
2. Sobolewski & Helms (1989) — metal/Si₃N₄/Si Schottky diodes; candidate for the nitride‑interface limitations (claims 41, 46/47, 57, 62‑66).
3. Goodnick (1981) — metal/SiO₂/Si contacts; candidate for the oxide interface‑layer claims (the IPR's primary reference).
4. Card & Rhoderick (1971) / Aboelfotoh (1989) — thin oxide interface layer altering the effective Schottky barrier; candidates for claims 1, 36, 41, 46.
5. Chang (1971) — the specific‑contact‑resistance metric; relevant only to the numerical Ω·μm² limitations, and § 102 typically fails where the reference does not disclose the claimed resistance values as such.
6. Tersoff (1984) / Heine / Louie — the MIGS theory; § 102 anticipation is nearly impossible with a pure theory paper (no apparatus/method steps), so these are § 103 background.

General § 102 caveat: The '423's independent claims pair the interface layer with result‑oriented limitations — "sufficiently thick to depin the Fermi level … yet sufficiently thin to provide a specific contact resistance ≤ [X] Ω·μm²." Even where a reference shows an interfacial layer (Schroen, Sobolewski, Goodnick, Aboelfotoh), anticipation requires that the reference disclose the depinning‑vs‑thickness/contact‑resistance relationship as claimed — the very point the patent stresses (the U‑shaped FIG. 8 curve). Expect the strongest disputes to be over whether any single reference discloses the contested operating window, not merely a thin interfacial layer.

6. Caveats and flagged contradictions

1. List provenance. Items 1–27 (U.S.), the foreign documents, and the NPL set are the '423‑family citation set. I did not verify each against the printed front page of US 7,084,423 specifically; some (e.g., US 2005/0037557 Doczy, US 6,680,224 Shin) may belong only to a later family member's citation column. Treat those as lower confidence.
2. IPR petitioner conflict. Your earlier patent summary attributed IPR2020‑01182 to Unified Patents (following the Google Patents listing), while the litigation summary attributed it to Samsung and the Docket Alarm petition documents I found this session are captioned Samsung Electronics Co., Ltd. v. Acorn Semi, LLC with a Schubert declaration (Ex. 1003) and a Samsung "Updated Mandatory Notices" filing. Per the search results, the petitioner is Samsung; the Google Patents "Unified Patents" attribution appears to be an error. Flagging rather than auto‑correcting.
3. Challenged‑claim count conflict. The patent summary says claims 62–64 and 66; the litigation summary says 62–64 and 65. The petition language I retrieved uses 62‑64 and 66. Unresolved here.
4. No statutory‑basis record. I do not have the '423's Office actions, so I cannot confirm which cited references the Examiner applied under § 102 versus § 103. The § 102 column above is a technical relevance assessment, not a record of prosecution usage. The one documented fact is the petition's statement that claims 62‑64 and 66 faced no cited art at all.

I'll pull the prior-art record for the '423 patent, including the references cited on its face and the IPR2020‑01182 petition art, before building the §103 analysis.

I have the IPR art. Now let me pin down the claim 62 language and the face-of-patent references cited.

Let me get the verbatim claim 62 and confirm the front-page references of the '423.

Obviousness Analysis — U.S. Patent 7,084,423 under 35 U.S.C. § 103

Scope note on sources. This analysis builds on the two prior sections (Patent summary; Litigation summary) and uses (i) the prior-art record retrieved for the '423 and its family — the front-page "References Cited / Other Publications" set, the IPR2020‑01182 petition and Acorn's Preliminary Response, and the sibling IPR grounds; (ii) the specification's own background admissions (which are usable as applicant admissions); and (iii) the prosecution history retrieved from Exhibit 1002 (the March 23/April 4, 2005 amendments). The Google Patents page as fetched did not render a formatted "Prior Art" citation list, so I reconstructed the art of record from the References Cited page images on the family's printed patents and the IPR record. Where a reference's assignment to the '423's own front page specifically (as opposed to a family member) could not be confirmed this session, I say so.

⚠️ Contradiction flagged (per your instruction). The earlier Patent summary section states IPR2020‑01182 was filed by Unified Patents and describes it as "Not Instituted – Procedural" (following the Google Patents litigation blurb). The actual PTAB papers retrieved this session are captioned "Samsung Electronics Co., Ltd., Petitioner v. Acorn Semi, LLC, Patent Owner, Case IPR2020‑01182, U.S. Patent No. 7,084,423." The Litigation summary section (Samsung, petition filed 2020‑06‑24) matches the PTAB record and should be treated as authoritative over the Google Patents "Unified Patents" attribution. The two prior sections also disagree on the challenged set (62–64 & 66 vs. 62–64 & 65); Dr. Schubert's declaration and the petition materials consistently say claims 62–64 and 66, so I use that.

1. Legal framework applied

• Governing law: The '423 has a filing/priority date of 2002‑08‑12, so it is a pre‑AIA patent. § 103(a) applies in its pre‑AIA form (TSM/Graham, as refined by KSR Int'l v. Teleflex, 550 U.S. 398 (2007)). Any reference published before 2002‑08‑12 (or before 2001‑08‑12 for § 102(b)) is available. Goodnick (1981), Schmidt (1988), Tung (1984), Tersoff (1984), Thanailakis (1975/76), Wittmer/Freeouf (1993), Waldrop (1988/92/93) and Schroen (1975/76 issue) are all § 102(b) art on their face.
• Not prior art: the co-pending U.S. App. 10/342,576 (filed 2003‑01‑14, incorporated by reference) and Acorn's own Grupp '483 (US 7,176,483, filed 2004‑01‑07). Both post-date 2002‑08‑12 and share inventors/assignee. Samsung's "benefit‑disentitlement" attacks in the sibling IPRs turned on whether later family claims could reach back to the 2002 date; those attacks do not apply to the '423, whose own claims indisputably get the 2002 date.
• Level of ordinary skill (POSITA): a B.S./M.S. in EE, applied physics, or materials science with ~2–5 years in semiconductor process/device engineering, or a Ph.D. in semiconductor device physics — with working knowledge of Schottky‑barrier theory (Bardeen surface states, Tersoff/MIGS), MIS/tunnel‑oxide contacts, and Si surface passivation (thermal oxidation, RTN, HF‑last cleans).
• Claim‑construction overlay (important): In the E.D. Tex. action, claim 62 was held indefinite because "generally dependent" is a term of degree lacking reasonable certainty (order adopted by Judge Gilstrap 2020‑12‑10; the Board then denied institution under § 314(a) on that basis). This does not decide § 103, but it means the scope of the single limitation that most of the § 103 battle turns on is itself legally indeterminate — a fact that cuts against any confident "all limitations disclosed" mapping.

2. The claims that matter for § 103

Internally consistent pairing to note: claim 41's "Fermi level of the semiconductor independent of the Fermi level of the conductor" and claim 62's "contact resistance generally dependent on the workfunction of the conductor" describe the same physical end state (Schottky–Mott, Φ_B = Φ_M − χ_S) — depinning is what converts an "independent‑of‑metal" pinned junction into a "dependent‑on‑metal" tunable one. No contradiction, but the drafters used two different linguistic routes to the same concept, which matters for how prior art maps.

3. Prior art of record and what each reference teaches

4. Ground‑by‑ground § 103 analysis

Ground A — Goodnick alone (the ground actually litigated)

Claim 62. Goodnick discloses every structural element (Si + metal + intervening thin oxide) and, on petitioner's reading, both prongs of the "depin" limitation via parallelism with Rhoderick/Sobolewski. Motivation: Goodnick itself.

Why this ground is weak. (a) Acorn's evidence — including Dr. Goodnick's own declaration — is that "I was referring only to the fact that the dangling bonds in the silicon are passivated" and that a POSITA would not read his paper as showing distinct Al₂O₃/SiO₂ layers. Under In re Preda the inference must be one the artisan "would reasonably be expected to draw"; Goodnick's author denying the inference is strong rebuttal. (b) Goodnick gives no electrical characterization — it cannot establish "a specific contact resistance that is generally dependent on the workfunction of the conductor," and it expressly leaves the post‑metallization SiO₂ thickness unknown. (c) The extra Al₂O₃ barrier is unaccounted for. Goodnick standing alone is a shaky § 103 ground for claim 62.

Ground B — Goodnick + Rhoderick/Sobolewski

Claims 62, 63, 64, 66 (and 1). Rhoderick/Sobolewski supply the missing element: an interfacial insulator reduces penetration of metal wavefunctions = MIGS suppression, i.e., the second prong of the patent's own depinning definition ("all, or substantially all, dangling bonds … terminated, and the effect of MIGS … overcome, or at least reduced").
Motivation to combine: both references address the same known failure mode (barrier height insensitivity to metal workfunction) in the same structure (metal/thin‑insulator/Si); a POSITA seeking a tunable barrier would naturally pair a passivating oxide with the known MIGS‑decoupling effect of an interfacial insulator. This is the strongest conventional combination against claim 62's "thickness sufficient to depin" prong. It remains exposed on the "thin enough" prong (Goodnick's only thickness teaching is the direction "thicker oxide → suppressed current," which says nothing about how thin is achievable while retaining workfunction dependence).

Ground C — Goodnick + Schmidt 1988 (the strongest single combination I can identify)

Claim 62, and by extension 41/46/47–56. Schmidt's title and teaching are, functionally, the mirror image of claim 62's second limitation: a thin oxide layer between metal and Si increases the dependence of Schottky barrier height on metal work function. Because barrier height maps monotonically to specific contact resistance (the patent says so itself, col. 13–15), a junction whose barrier height "generally depends" on Φ_M necessarily has a specific contact resistance "generally dependent on the workfunction of the conductor."
Motivation to combine: (i) same field, same structure (metal/thin oxide/Si), same problem (pinning); (ii) the result of the combination is exactly the goal the '423's own Background states — tunable barrier height; (iii) both references are in the same cited "Other Publications" set, showing they were contemporaneously recognized as a coherent body of work; (iv) KSR design‑incentive reasoning: a finite, identified set of thin‑insulator chemistries/thicknesses with predictable results. This is the ground I would press hardest.

Ground D — Goodnick + Taubenblatt 1982 + Jammy (+ Chang, Kim)

Claims to a metal‑oxide separation layer, oxide‑of‑titanium/TiO₂‑type spacers, and the very‑low‑resistance dependents (≤ 10, ≤ 1 Ω‑μm²). Gauged at the sibling IPRs, the Board held petitioner had not shown sufficient motivation to combine Goodnick with Taubenblatt in the manner proposed (see the Winston/PTAB materials for IPR2020‑01282), and rejected the "best of both worlds" resistance rationale because quantum tunneling dominates through such thin layers and the bulk resistivity of TiO₂ vs Al₂O₃ is immaterial. So this ground is weak for the ultra‑low‑resistance claims unless the petitioner supplies better evidence of why a POSITA would have selected a lower‑barrier spacer and why the resulting resistance would land in the claimed sub‑10 Ω‑μm² range.

Ground E — Schroen, alone or as primary

Claims reciting an interface layer < 1 nm, and the plain structural claims. Schroen teaches a 10–100 Å non‑conductive film at the junction — its 10 Å lower bound is exactly 1 nm, immediately adjacent to the claimed "<1 nm" region (In re Aller, 220 F.2d 454 (CCPA 1955)). But Schroen teaches away from thinner films ("<10 Å thick is unsatisfactory due to lack of uniformity or operating stability") and, more damagingly for the petitioner, expressly states that the film makes resistance independent of metal workfunction — the obverse of claim 62's "generally dependent" limitation. That is precisely the argument Acorn used at prosecution and why the reference was overcome. Schroen therefore hurts the petitioner more than it helps, except possibly against bare "interface layer present" claims if any independent claim lacks the dependency limitation.

Ground F — Schottky–Mott relation + Thanailakis/Sze/Rhoderick & Williams → claims 46 and 57

Claims 46 and 57 require only that the metal's workfunction be "approximately equal to" the conduction‑band (46, n‑type) or valence‑band (57, n‑type) edge. The '423's own Background reproduces Eq. (1), Φ_B = Φ_M − χ_S, and its specification lists metals with workfunctions above and below Si. Once the Fermi level is depinned (Grounds B/C), picking a metal whose Φ_M sits at the desired band edge to minimize (claim 46) or maximize (claim 57) the barrier is the textbook application of an equation the applicant itself put in the specification, confirmed by Thanailakis' measured workfunction/barrier‑height data on clean Si. This is the weakest portion of the claim set — a design incentive with a predictable result. Any validity story for 46/57 must rest on the depinning step, not on the metal selection.

Ground G — RTN/UHV nitridation + HF‑last clean → claims 19/27 and 67–69

Claim 69 (immersion in a liquid containing H and F ions) reads on the standard HF‑last clean known in the art long before 2002, which intentionally H‑/F‑terminates the Si surface before metal deposition. Claim 67 (heating in nitrogenous material) reads on conventional Rapid Thermal Nitridation, which the specification itself acknowledges (and disparages only as to temperature — "lower than temperatures conventionally used for RTN"). Optimization of anneal temperature, ambient partial pressure, and pulse duration to obtain a self‑limiting monolayer is routine parameter optimization (In re Boesch / In re Aller). Method claims 19/27 are, on this record, highly vulnerable — subject to the caveat that I did not retrieve their verbatim text.

Ground H — Numerical resistance ranges (claims 41, 46–56 dependents)

Ranges of 2500/1000/100/50/10/1 Ω‑μm² are obvious "if the prior art discloses a range encompassing or overlapping the claimed range," or where a POSITA would have expected the result from the prior art's direction (In re Woodruff, 919 F.2d 1575 (Fed. Cir. 1990)). Goodnick's "if the oxide is too thick, current flow … may be severely suppressed" gives the direction (go thin → lower resistance) but no numbers. Absent a reference reporting sub‑10‑Ω‑μm² contacts, the petitioner must rely on "obvious to try" over a finite range — which KSR permits where there is "a finite number of identified, predictable solutions," but which weakens where the art contains no data and where the patent shows the relationship is non‑monotonic (see § 5).

5. The non‑obviousness case the petitioner must overcome

1. Criticality/counter‑intuition of the two‑sided thickness window. The patent's FIG. 8 U‑shaped curve — resistance falls with decreasing thickness, then rises again as the layer gets thinner because MIGS reassert themselves — is the heart of the invention. The prior art's teaching is monotonic and one‑directional ("thick oxide suppresses current" ⇒ "thinner is better"). A POSITA following Goodnick would be led through the claimed optimum, not to it. This is the classic In re Woodruff "critical range / different result" argument, and it is the strongest § 103 rebuttal in the file.
2. Author testimony contradicting the mapping. Dr. Goodnick's declaration that his paper shows neither distinct Al₂O₃/SiO₂ layers nor MIGS suppression is unusually damaging to Ground A/B.
3. Objective indicia (Graham factors) that Acorn asserted and that the Board did not reach (institution denied on § 314(a)): long‑felt need, unexpected results, time lag (1981 → 2002), industry praise, and the petitioner's own writings.
   • Nexus: moderate for claim 62 (structure‑tied); weak for the pure numerical‑range and metal‑selection claims, which are ordinary design choices — an important limitation on how far these indicia travel.
4. Practical effect of indefiniteness. Because "generally dependent" was held indefinite, the very limitation Ground C maps onto is of indeterminate scope. Practically, that neutralizes claim 62 as an assertion vehicle but also means the § 103 "obviousness" verdict on claim 62 is somewhat artificial — you cannot cleanly say art discloses a limitation whose metes and bounds are legally undefined.

6. Bottom line

Most likely to succeed combination: Goodnick (1981) in view of Schmidt (1988), optionally further in view of Rhoderick/Sobolewski — motivation: both references concern thin interfacial oxides on Si metal contacts, both address the workfunction‑dependence/pinning problem, and Schmidt supplies the express teaching that a thin oxide increases the dependence of barrier height (and hence contact resistance) on metal workfunction, which is the functional limitation of claim 62. Most likely to fail: Goodnick alone, and any Goodnick + Taubenblatt‑based ground, both of which the PTAB already found insufficiently motivated in the sibling proceedings.

7. Confidence and uncertainty

High confidence: verbatim claim 62 text; the amendment history ("Fermi level of the semiconductor" → "metal/conductor" in claims 1, 19, 57); Schroen = U.S. 3,983,264 and the "<10 Å unsatisfactory" / "independent of workfunction" passages as recited in the prosecution history; the IPR2020‑01182 identity (Samsung) and single‑Goodnick ground; the claim‑62 indefiniteness ruling; the Board's insufficient‑motivation finding on Goodnick + Taubenblatt in the sibling '395 IPR line.

Medium confidence: that Schmidt 1988 was cited on the '423's own front page (I confirmed it in the Acorn family's cited "Other Publications" set, not in a '423‑specific page image); the identity/date of "Sobolewski" and "Taubenblatt 1982" as petition exhibits (I have them only by short‑form name from the petition/POPR and petitioner's reply).

Explicitly not established: verbatim text of independent claims 1, 19 and 36 and the total claim count/complete independent‑claim list; whether Goodnick, Schmidt or Schroen are each individually listed on the '423's printed front page (vs. a family member); any 2026 CAFC docket (negative finding only). Locate-and-verify items: the '423's face‑of‑patent References Cited page (Google Patents "Info" → References Cited) and the IPR2020‑01182 Exhibit 1004 (Goodnick) and Exhibit 1002 (prosecution history) at the PTAB docket.

Primary URLs used: https://patents.google.com/patent/[US7084423](/patent/US7084423)/en · https://www.docketalarm.com/cases/PTAB/IPR2020-01182/Inter_Partes_Review_of_U.S._Pat._7084423/ (POPR, Ex. 1002) · https://ptacts.uspto.gov/ptacts/public-informations/petitions/[1538382](/patent/1538382)/download-documents (POPR §V–VI; petition §IV.C) · https://www.winston.com/a/web/[248292](/patent/248292)/PTAB-IPR2020-01282-20.pdf (sibling § 103 motivation findings) · https://www.patents-review.com/a/[10217758](/patent/10217758)-method-depinning-fermi-level-semiconductor-electrical.html (claim text) · https://ptabdata.blob.core.windows.net/files/2020/IPR2020-01241/v41_Ex.%[201141](/patent/201141).pdf (asserted claim set).