US 7435608

US Patent 7435608 — Search Results and Summary

Search results / source status

• USPTO / Google Patents record confirmed: The patent record exists and matches the full text supplied. Key corroborating sources: Google Patents (patents.google.com/patent/US7435608/en) and USPTO.report (uspto.report/patent/grant/7435608).
• CAFC 2026 docket search: I searched for this patent number in connection with Federal Circuit appeal dockets for 2026 (queries including "CAFC 2026," "7435608," and inventor name). No CAFC 2026 appeal docket entries referencing this patent were found. I cannot rule out an appeal filed under a different docket-number/patent reference convention, but based on available searches there is no indication of 2026 CAFC litigation involving US7435608.
• I found no contradictory search results; the web results are consistent with the supplied patent text, which I treat as authoritative.

Bibliographic summary

Abstract: A III-V group nitride system semiconductor self-standing substrate is made of III-V group nitride system semiconductor single crystal with a hexagonal crystal system crystalline structure. The substrate is provided with a surface that is off-oriented 0.09 degrees or more and 24 degrees or less in the a-axis or m-axis direction from the C-face of the substrate.

Independent claims — plain-language overview

The granted patent contains 15 claims, all method claims (the earlier substrate-composition claims from the parent application were not carried into this divisional grant). There are three independent claims: claims 1, 2, and 10.

• Claim 1 — Method of making a self-standing III-V nitride substrate for a semiconductor laser. You start with a sapphire (hetero-)substrate whose surface is tilted ("off-oriented") 0.07°–20° from the sapphire C-face in the m-axis direction. You epitaxially grow a III-V nitride single-crystal layer on it, then separate that layer from the sapphire. The resulting free-standing substrate has a predetermined off-orientation in the a-axis direction. (Because of the known sapphire/GaN epitaxial orientation relationship, an m-axis off-cut sapphire yields an a-axis off-cut GaN crystal.)

• Claim 2 — The mirror-image method. Same process as claim 1, except the sapphire surface is off-oriented 0.07°–20° in the a-axis direction, producing a self-standing substrate off-oriented in the m-axis direction.

• Claim 10 — Method of making a III-V nitride semiconductor wafer (substrate + epilayer). You provide a sapphire hetero-substrate off-oriented 0.07°–20° in either the m-axis or a-axis direction, grow and separate an epitaxial III-V nitride layer to form a free-standing substrate having a hexagonal crystal structure with a predetermined off-orientation in one of those directions from its C-face, and then homo-epitaxially grow a III-V nitride semiconductor layer on that self-standing substrate.

Selected dependent-claim limitations (for context):

• Claims 3 and 4: resulting substrate off-orientation is 0.09°–24.0°.
• Claims 5 and 6: the grown substrate's off-angle is about 0.8–1.5× the sapphire off-angle, per a linear relationship.
• Claims 7 and 8: sapphire off-orientation of 1°–20°.
• Claims 9 and 13: the semiconductor is InₓGaᵧAl₁₋ₓ₋ᵧN (0 ≤ x ≤ 1, 0 ≤ y ≤ 1, 0 ≤ x+y ≤ 1).
• Claims 11 and 12: in-plane dispersion of the substrate off-orientation is within ±1 degree.
• Claims 14 and 15: substrate thickness 200 μm to 1 mm.

Points of uncertainty

• No CAFC 2026 docket was found for this patent number; absence from my search results is not definitive proof of no pending appeal, since docket databases may index by case number or assignee rather than patent number.
• The patent's specification (from the parent application) describes the off-oriented substrate product, but the granted claims here are exclusively process claims — a distinction worth noting if you are comparing this divisional against its family members (e.g., US7253499, US7790489, both also by Shibata/Hitachi Cable).
• The assignment record shows Sumitomo Chemical as the most recent recorded assignee; Google's current-assignee display additionally lists Proterial Ltd., reflecting the Hitachi Metals renaming. I have not independently verified post-2016 chain-of-title beyond the recorded events above.

Based on my searches of available litigation and patent databases, I found no known litigation involving US Patent 7,435,608 (US7435608B2, "III-V group nitride system semiconductor self-standing substrate, method of making the same and III-V group nitride system semiconductor wafer").

Search results summary:

• Searches for "7435608" patent litigation, "US 7,435,608" litigation, "7435608" patent lawsuit, US7435608 litigation Unified Patents, and patent 7435608 infringed court case docket returned no litigation records, case dockets, PACER entries, CAFC decisions, or Unified Patents caselist entries referencing this patent number.
• The only substantive hit was the USPTO/Google Patents record itself (via uspto.report), which confirms the patent's prosecution and post-grant assignment history but shows no litigation events in its legal-event timeline.
• The patent's own legal-status history (as shown in the Google Patents record) reflects only administrative events:
  • Maintenance fees paid in 2012 and 2016
  • Assignments: Hitachi Cable → Hitachi Metals (2014) → SCIOCS (2015) → Sumitomo Chemical (2016)
  • Lapse/expiration for failure to pay maintenance fees (effective October 14, 2020)

Caveat: My searches were limited to general web and litigation-oriented databases accessible at this time. I did not independently confirm against PACER's full docket search or the USPTO Patent Center litigation search, which may require authenticated access. If a case exists under a different reference (e.g., asserted via a related family member such as the parent application US10/928,739 or related patents US7253499B2, US7790489B2, or the cited "Vicinal gallium nitride substrate" patent US7118813B2 assigned to Cree), it would not have appeared in these patent-number-specific searches.

Bottom line: No litigation is known for US Patent 7,435,608 based on the searches performed. If you need a definitive clearance opinion, I recommend a PACER party-search and a commercial docket search (e.g., DocketNavigator, Unified Patents portal) for confirmation.

Proceedings overview

There are zero AIA trial proceedings (IPR / PGR / CBM) on file for US 7435608 — the USPTO Open Data Portal ingest shows no trial history, and web searches (including PTAB and RPX-style databases) surfaced no petition, institution decision, settlement, or Federal Circuit appeal naming this patent. The defensive posture for a defendant is neutral-but-uncontested: the patent has never been tested before the PTAB, so no claim has been canceled or confirmed by an AIA trial, and no § 315(e)(2) estoppel yet binds any would-be petitioner.

For each proceeding (most-impactful first — none exist):

No proceedings to report. There are no IPR, PGR, or CBM dockets (e.g., IPR20XX-XXXXX) associated with U.S. Patent No. 7,435,608. I will not invent proceeding numbers, judge panels, institution decisions, Final Written Decisions, settlements, or appeals, because none are public.

Strategic summary

Claim-level status. All fifteen claims of US 7435608 (claims 1–15; the patent's substantive claims are method claims 1–15 directed to making a III-V nitride self-standing substrate with controlled off-orientation from an off-oriented sapphire hetero-substrate) remain UNTESTED by the PTAB. No claim is canceled, no claim has been sustained in an IPR, and no petition has even been filed — as far as the USPTO ODP data and public web sources show. The only "status" events on the file are patent-office administrative ones: the patent lapsed for failure to pay maintenance fees effective 2020-10-14 (USPTO legal-event codes LAPS / FP, "PATENT EXPIRED DUE TO NONPAYMENT OF MAINTENANCE FEES UNDER 37 CFR 1.362"), after fee payments in 2012 and 2016. Ownership migrated from Hitachi Cable → Hitachi Metals → Sciocs Company Limited → Sumitomo Chemical Company, Limited (2014–2016 assignments), which is worth verifying if you are being asserted against by an entity in that chain.

Estoppel landscape. Because no AIA proceeding has ever been instituted, § 315(e)(2) estoppel has not attached to anyone. A defendant facing assertion today is free to raise any and all prior-art grounds (anticipation under § 102, obviousness under § 103, plus § 112 issues) in district court or in a newly filed IPR — subject only to the IPR timing bar of § 315(b) (a petition must be filed within one year of being served with a complaint). There is no PTAB history to narrow or pre-clear those grounds. The practical caveat: this patent's asserted claims are all method of making claims, and the patent is expired (lapsed 2020), which matters because IPR is generally available for expired patents but damages exposure and the practical value of a validity fight must be weighed against the expired status and the now-remote priority chain.

Pattern signals. There are no repeat-petitioner patterns, no Unified Patents or defensive-aggregator involvement, and no aggressive patent-owner PTAB litigation history — because there has been no PTAB litigation at all. The related family (parent application US 10/928,739, abandoned; sibling patents 7,253,499; 7,790,489; 7,622,791; and others in the same Hitachi Cable/Sumitomo nitride-substrate portfolio) likewise shows no surfaced IPR activity in these searches. The absence of PTAB challenges is itself informative: this is a process/method patent in a niche GaN-substrate manufacturing field with an apparently narrow commercial assertion footprint — the kind of patent that simply never attracted a petition, rather than one that has been battle-hardened.

Recommended next steps

• There is no Final Written Decision to cite. If you are a defendant and your analysis depends on PTAB invalidity, the absence of activity means you cannot lean on any PTAB record — but it also means your hands are completely untied. You can assert any prior art (e.g., the references already cited during prosecution: US 5,814,533; JP H11-251253; JP 2000-223743; US 2002/0197825 A1; JP 2003-165799; US 2003/0205717 A1; US 2005/0093003 A1; US 2005/0208687 A1 — or closer art like US 7,118,813 "Vicinal gallium nitride substrate for high quality homoepitaxy" and the non-patent literature on VAS/DEEP listed in the file) without any estoppel constraint.
• Confirm the enforcement posture before spending on an IPR. The patent expired for nonpayment of maintenance fees on 2020-10-14 (37 CFR 1.362; see the LAPS/FP legal events). If the demand is for past damages only, evaluate whether IPR is worth the cost versus a district-court validity defense; if the demand targets ongoing conduct, confirm the asserted claims and that the fee was not reinstated under 37 CFR 1.378.
• Check the current assignee and standing. Verify via USPTO Assignment (the last recorded chain is Sumitomo Chemical Company, Limited, effective 2016-01-20) who actually owns the patent and has standing to sue, and confirm no reissue, reexamination, or ex parte proceeding exists that the ODP AIA-trial feed would not capture (the structured block covers only AIA trials — ex parte reexamination certificates would appear on the face of the patent, and none are listed).
• If you file an IPR anyway, note that the statutory one-year clock under § 315(b) runs from service of a complaint, and the PTAB's one-year trial deadline runs from institution — but with zero prior proceedings there are no procedural shortcuts or estoppel traps to navigate.

Inventors

• Masatomo Shibata — sole named inventor. Employer at filing: Hitachi Cable, Ltd. (Hitachi, Ibaraki, Japan), where he worked in the compound-semiconductor / nitride group. The application was filed as a Hitachi Cable employee invention (JP priority 2004-162189 filed 2004-05-31; US parent 10/928,739 filed 2004-08-30; this divisional 11/589,771 filed 2006-10-31).
• Unusual-departure pattern: not evidenced. No data found indicating Shibata left Hitachi Cable shortly after filing; the record is consistent with a normal employee-inventor assignment to his employer. Shibata continued to appear as an inventor on later Hitachi-Cable-lineage nitride patents (e.g., family filings through Hitachi Cable/Hitachi Metals into 2009–2011), so no fire-sale precursor pattern is apparent.

Original assignee

• Hitachi Cable, Ltd. is the entity named on the issued patent (front page: "Original Assignee: Hitachi Cable Ltd").
• Line of business: wires/cables, and — relevant here — III-V compound semiconductor materials including GaN self-standing substrates and epitaxial wafers (the exact product class of the claims, which are drawn to methods of making GaN self-standing substrates for semiconductor lasers). SCIOCS, the entity that later took the patent, was originally Hitachi Cable's compound-semiconductor operation (established ~2001 in Hitachi, Ibaraki) and manufactured/sold GaN substrates and epiwafers. So the original assignee shipped products embodying the claimed subject matter.
• Current status: Hitachi Cable no longer exists as a separate entity — it was absorbed into Hitachi Metals, Ltd. (effective 2013-07-01), which renamed itself Proterial Ltd (2023). The GaN substrate business line was sold to Sumitomo Chemical in 2015 and is now operated within Sumitomo Chemical.

Assignment timeline

USPTO Assignment Center records for US 7435608 (cross-verified against Google Patents legal-events feed, which mirrors the USPTO reel/frame records). The chain is entirely among Japanese operating manufacturers — no LLCs, no licensing vehicles.

• 2013-07-01 (effective) / recorded 2014-12-15 — Reel 034630/0897

  • Conveyance: Merger and Change of Name
  • Assignor: Hitachi Cable, Ltd. and Hitachi Metals, Ltd.
  • Assignee: Hitachi Metals, Ltd.
  • Correspondent: Not retrievable from available sources — see note below.
  • Context: Internal corporate consolidation — Hitachi Cable merged into Hitachi Metals (Hitachi-group reorg), effective mid-2013, recorded late 2014.

• 2015-04-01 (effective) / recorded 2015-07-24 — Reel 036181/0104

  • Conveyance: Company Split
  • Assignor: Hitachi Metals, Ltd.
  • Assignee: SCIOCS Company Limited
  • Correspondent: Not retrievable from available sources — see note below.
  • Context: Carve-out of Hitachi Metals' compound-semiconductor materials business into SCIOCS, the vehicle formed in connection with the sale of that business to Sumitomo Chemical (announced 2015).

• 2016-01-20 (effective) / recorded 2016-02-16 — Reel 037827/0453

  • Conveyance: Assignment of Assignor's Interest
  • Assignor: SCIOCS Company Limited
  • Assignee: Sumitomo Chemical Company, Limited
  • Correspondent: Not retrievable from available sources — see note below.
  • Context: Completion of the acquisition — SCIOCS (and with it this patent) transferred to Sumitomo Chemical, which thereafter operated SCIOCS as a subsidiary until absorbing it outright in October 2022.

Correspondent note (stated plainly, not fabricated): I could not pull the correspondent-of-record names from the USPTO Assignment Center pages in my available searches (the database requires interactive reel/frame lookups that returned no citable content via my tools). The reel/frame numbers, conveyance types, parties, and dates above are corroborated by the Google Patents legal-events record. I will not guess at attorney names. The absence of correspondent data means the repeat-correspondent signal below is scored "unclear," not "present."

Also relevant: the original inventor-to-company assignment (Shibata → Hitachi Cable) is implicit in the issued-patent front page but no reel/frame for it surfaced in my sources. The patent lapsed 2020-10-14 for non-payment of maintenance fees (recorded 2020-12-08; status "Expired — Fee Related"), so no further transfers were recorded after 2016.

Timeline diagram

timeline
    title Ownership of US 7435608
    2004 : Filed by Hitachi Cable
    2008 : Granted to Hitachi Cable
    2013 : Hitachi Cable merges into Hitachi Metals
    2014 : Merger recorded at USPTO
    2015 : Company split to SCIOCS
    2016 : Assigned to Sumitomo Chemical
    2020 : Lapsed for unpaid maintenance fees

NPE / troll-pattern signals

1. Shell-entity transfer — Not present. Every assignee (Hitachi Cable, Hitachi Metals, SCIOCS, Sumitomo Chemical) is a manufacturing operating company; no "IP/Holdings/Licensing" LLC, no registered-agent address, no single-purpose Delaware/Texas LLC anywhere in Reels 034630/0897, 036181/0104, 037827/0453.
2. Known asserter in the chain — Not present. None of the assignees appears on public NPE lists (Acacia, Marathon, IV, Wi-LAN, Conversant, RPX/Unified high-frequency plaintiff directories, etc.). SCIOCS/Sumitomo Chemical are product makers (GaN substrates, GaN/GaAs epiwafers).
3. Repeat correspondent across the chain — Unclear. Correspondent identities were not retrievable in my searches, so recurrence cannot be assessed. No NPE-correspondent pattern is otherwise evidenced.
4. Cascading transfers — Not present. Three transfers in ~2.5 years (2013–2016) map cleanly onto a documented corporate sequence — merger (Hitachi Cable → Hitachi Metals), company split (→ SCIOCS), acquisition completion (→ Sumitomo Chemical). Not chained LLCs with common principals.
5. Pre-litigation transfer — Not present. No infringement litigation naming US 7435608 was found in any period, and the last transfer (2016) postdates the patent's productive life; the patent expired in 2020 without any recorded assertion.
6. Bankruptcy fire-sale — Not present. Hitachi Cable's disappearance resulted from a solvent Hitachi-group merger into Hitachi Metals, not Chapter 7/11. No insolvency proceedings identified.
7. Privateering — Not present. Sumitomo Chemical bought the business to operate it (SCIOCS remained a manufacturing subsidiary and was later fully absorbed), not to assert against Hitachi/competitors on the seller's behalf. No SEC/8-K or press coverage suggests otherwise.
8. Defensive aggregator (anti-NPE) — Not present. Chain does not terminate at RPX, AST, LOT, Unified Patents, or OIN.

Verdict

Operating-company assertion

Justification: The recorded chain (Reel 034630/0897 → 036181/0104 → 037827/0453) moves the patent exclusively among Japanese operating manufacturers — Hitachi Cable, Hitachi Metals, SCIOCS, and Sumitomo Chemical — all of which make/sell GaN substrates and epiwafers of the type claimed, with the last two being the current product-making owner lineage. No shell entities, no known NPE, no litigation, and no bankruptcy appear in the record. Caveat: the "assertion" element is unproven — I found no suit naming this patent, and the patent lapsed in 2020 for non-payment of maintenance fees; the verdict reflects the total absence of any NPE signal rather than active enforcement. Verification: search patent number 7435608 at https://assignmentcenter.uspto.gov/ or https://assignment.uspto.gov/patent/index.html.

Identification of the target patent (searched, not auto-corrected)

I searched the USPTO-ecosystem sources for the alphanumeric ID 7435608 (no leading zeros, no other numbering variant). The record returned is:

• US7435608 B2 — "III-V group nitride system semiconductor self-standing substrate, method of making the same and III-V group nitride system semiconductor wafer"
• Inventor: Masatomo Shibata
• Original assignee: Hitachi Cable, Ltd. (current chain: Hitachi Cable → Hitachi Metals (2014) → SCIOCS (2015) → Sumitomo Chemical (2016))
• Application: US 11/589,771, filed 2006-10-31 (divisional of abandoned US 10/928,739, filed 2004-08-30)
• Priority: JP 2004-162189, filed 2004-05-31
• Granted: 2008-10-14; expired 2020-10-14 (lapse for non-payment of maintenance fees)
• Sources: https://uspto.report/patent/grant/7435608 and https://patents.google.com/patent/US7435608/en

Because the application was filed before March 16, 2013, pre-AIA 35 U.S.C. § 102 governs. The operative priority date is May 31, 2004, and the earliest U.S. filing date (for § 102(b)/(e) purposes) is August 30, 2004 (parent) / benefit chain. I use those dates below.

Claims at issue (for claim-mapping)

All 15 claims are method claims. The independent claims are:

• Claim 1 – making a self-standing III-V nitride substrate for a semiconductor laser: (a) provide a sapphire hetero-substrate off-oriented 0.07°–20° in the m-axis direction from C-face; (b) epitaxially grow a III-V nitride single-crystal layer; (c) separate the layer to obtain a self-standing substrate with a predetermined off-orientation in the a-axis direction.
• Claim 2 – same as claim 1, but the sapphire is off-oriented in the a-axis direction and the resulting substrate is off-oriented in the m-axis direction.
• Claim 10 – method of making a wafer: sapphire hetero-substrate off-oriented 0.07°–20° in either m- or a-axis; grow epitaxial layer; separate to a self-standing substrate; then homo-epitaxially grow a III-V nitride layer on it.

Dependent claims 3–9 and 11–15 add: resulting-substrate off-orientation 0.09°–24° (3, 4); 0.8–1.5× linear off-angle transfer from the hetero-substrate (5, 6); hetero-substrate off-orientation 1°–20° (7, 8); InₓGa_yAl₁₋ₓ₋_y_N composition (9, 13); in-plane dispersion ±1° (11, 12); and 200 μm–1 mm thickness (14, 15).

Analytical caution up front: every independent claim requires the combination of (i) a sapphire substrate with a direction-specific, numerically bounded miscut, (ii) epitaxial growth, and (iii) separation into a self-standing substrate. A reference that discloses only part of that combination cannot be a true § 102 anticipation; at best it supports an obviousness (§ 103) argument. The disclosures of several Japanese-language references could not be fully verified in the tool results available to me, so where I flag uncertainty, the determination should be confirmed against the full text in the USPTO Global Dossier / PAIR before relying on it.

Patent citations of record for US 7435608 B2

1. US 5,814,533 A (Rohm Co., Ltd.)

• Full citation: US 5,814,533 A, "Semiconductor light emitting element and manufacturing method therefor," Rohm Co., Ltd.
• Filing date: 1994-08-09; granted: 1998-09-29
• Description: A blue/gallium-nitride-compound light-emitting element and its manufacturing method. Grows buffer and device layers (GaN/AlGaN/InGaN) on sapphire by MOCVD, with annealing to activate p-type layers. It is background art on nitride epitaxy and device fabrication; no teaching of separating a thick grown layer into a self-standing nitride substrate.
• § 102 assessment vs. claims: Does not potentially anticipate claims 1, 2, or 10 because it lacks the separation step and discloses no direction-specific 0.07°–20° sapphire miscut correlated to the off-orientation of a separated substrate. At most a § 103 background reference for the epitaxial-growth step. No claim of 7435608 appears fully anticipated.

2. JP H11-251253 A (Nichia Chemical Industries) — cited as JPH11251253A

• Full citation: JP 11-251253 A, "Method for manufacturing nitride semiconductor substrate and nitride semiconductor substrate," Nichia Chemical Industries, Ltd.
• Filing date: 1998-03-05; published: 1999-09-17
• Description: The '608 specification itself cites this as a known method of making a self-standing GaN substrate: GaN is grown on sapphire by ELO and the sapphire is then removed by etching — i.e., the general hetero-substrate growth-plus-separation concept.
• § 102 assessment: Potentially relevant to the generic method skeleton of claims 1, 2, and 10 (sapphire substrate → grow nitride → separate to self-standing GaN substrate). However, nothing in the record shows that it discloses the required numerical miscut bounds (0.07°–20°), the specific m-axis/a-axis direction mapping, or the resulting-substrate off-orientation. If the full text contains such direction/angle teaching it could be a § 102(b) candidate (published >1 year before Aug. 30, 2004); otherwise it is a § 103 reference. Anticipation of claims 1–15 is not established on the available record.

3. JP 2000-223743 A (Sanyo Electric Co., Ltd.)

• Full citation: JP 2000-223743 A, "Nitride-based semiconductor light emitting device and method of growing nitride semiconductor layer," Sanyo Electric Co., Ltd.
• Filing date: 1999-01-29; published: 2000-08-11
• Description: Nitride-based light-emitting device and a nitride-layer growth method (per its title). This class of Sanyo work concerns growing device layers, typically on off-angle substrates, but is not a self-standing-substrate separation process.
• § 102 assessment: Does not appear to anticipate claims 1, 2, or 10 (no sapphire separation to a self-standing substrate meeting the recited off-orientation relationship). Pre-AIA § 102(b) prior art (published 2000), but useful mainly for § 103 on the growth-step/off-orientation motivation. No claim fully anticipated on the available record.

4. US 2003/0205717 A1 (Reena Khare et al.)

• Full citation: US 2003/0205717 A1, "Increasing the brightness of III-Nitride light emitting devices"
• Filing date: 2001-03-01; published: 2003-11-06
• Description: III-nitride light-emitting device improvements, in the direction of substrate surface preparation/miscut effects on device brightness. It is device-oriented rather than a method of making a freestanding substrate.
• § 102 assessment: Does not appear to anticipate the separation-based method claims 1, 2, or 10; it lacks the sapphire-miscut-plus-separation-to-self-standing-substrate combination. Timely prior art (§ 102(b), published 2003), but best characterized as a § 103 reference for the benefit of off-oriented substrates. No claim of 7435608 is anticipated on this record.

5. US 2002/0197825 A1 (Akira Usui) — and its counterpart JP 2003-178984 A (NEC), item 6

• Full citation: US 2002/0197825 A1, "Semiconductor substrate made of group III nitride, and process for manufacture thereof," inventor Akira Usui.
• Filing date: 2001-03-27; published: 2002-12-26
• Description: The '608 specification identifies this family (VAS — Void-Assisted Separation, cf. Oshima et al.) as a known route: GaN is grown through a mesh-like TiN thin film on a substrate such as sapphire with voids formed at the interface, enabling both separation and dislocation reduction of the GaN layer. This is the closest structural analog to the Example-1 manufacturing route used in '608.
• § 102 assessment: This is one of the most relevant prior-art families for claims 1, 2, and 10 because it teaches sapphire-based growth of a thick GaN layer and separation into a self-standing group-III nitride substrate. For true anticipation it must additionally disclose the sapphire miscut of 0.07°–20° in a specific (m- or a-axis) direction and the resulting off-orientation transfer. The '608 specification itself states that the prior art did not teach what off-direction/off-angle is proper or reproducible for such separated substrates — which argues the Usui VAS reference did not disclose those limitations. Thus it potentially anticipates only if the full text contains the direction-and-range miscut teaching; otherwise it is the strongest § 103 combination reference against claims 1, 2, 10, and their dependents.

6. JP 2003-178984 A (NEC Corporation) — counterpart of item 5

• Full citation: JP 2003-178984 A, "Group III nitride semiconductor substrate and method of manufacturing the same," NEC Corp. (priority/filing family with US 2002/0197825 A1).
• Filing date: 2001-03-27; published: 2003-06-27
• Description: The VAS (void-assisted separation) JP publication corresponding to the Usui US application — growth of group-III nitride through a TiN mesh/void layer on sapphire and separation of a freestanding substrate.
• § 102 assessment: Same analysis as item 5. Published 2003 (before the May 31, 2004 priority date), so it is § 102(a)/(b) prior art. Under pre-AIA practice its JP filing date alone cannot supply a § 102(e) date (Hilmer doctrine); only its publication date matters. Anticipation of claims 1/2/10 hinges on whether the miscut direction/range is disclosed, which is not established here.

7. JP 2003-165799 A (Sumitomo Electric Industries, Ltd.)

• Full citation: JP 2003-165799 A, "Single crystal gallium nitride substrate, growth method thereof and manufacturing method thereof," Sumitomo Electric Industries, Ltd.
• Filing date: 2001-09-19; published: 2003-06-10
• Description: The '608 specification cites this as the DEEP method — growing GaN on a GaAs substrate (removable by etching) through a SiN patterning mask, intentionally forming inverted-pyramidal facet pits that accumulate dislocations, leaving a low-dislocation freestanding GaN substrate.
• § 102 assessment: Does not anticipate claims 1, 2, or 10 because those claims require a sapphire hetero-substrate; DEEP uses a GaAs starting substrate. It is timely prior art (§ 102(b)) and relevant to the general "grow thick GaN and separate to a self-standing substrate" concept, but its GaAs-based route takes it outside the literal scope of the independent claims, so no anticipation finding is supportable on this record.

8. US 2005/0093003 A1 (Hitachi Cable, Ltd. — inventor Masatomo Shibata)

• Full citation: US 2005/0093003 A1, "III-V group nitride system semiconductor substrate," Hitachi Cable, Ltd.
• Filing date: 2003-10-29; published: 2005-05-05
• Description: A sibling application by the same inventor (Shibata) and same assignee (Hitachi Cable) concerning a III-V nitride substrate whose in-plane crystal-axis inclination vector converges on a specific point/region (flat-surface substrate with controlled off-axis distribution). This is related work by the '608 inventor rather than third-party art.
• § 102 assessment: Not § 102 prior art: under pre-AIA § 102(e), a U.S. patent is prior art only if "by another," and this reference is by the same inventive entity; it also published (May 2005) after the May 31, 2004 priority date. It does not anticipate any claim of 7435608. It is useful only as a family-context document (and it was itself the subject of the "Similar Documents" grouping, along with US 7,253,499 B2 and US 7,790,489 B2, which are related Hitachi Cable cases in the same family cluster).

9. US 2005/0208687 A1 (Sumitomo Electric Industries, Ltd.)

• Full citation: US 2005/0208687 A1, "Method of Manufacturing Single-Crystal GaN Substrate, and Single-Crystal GaN Substrate," Sumitomo Electric Industries, Ltd.
• Filing date: 2004-03-17; published: 2005-09-22
• Description: A method of manufacturing a single-crystal GaN substrate (and the substrate), from Sumitomo Electric. Because its U.S. filing date (2004-03-17) precedes the '608 priority date (2004-05-31), it can carry a § 102(e) prior-art date, and it is "by another" (Sumitomo vs. Hitachi Cable). This makes it one of the more dangerous references for claim validity if its disclosed process matches the claim elements.
• § 102 assessment: Potentially relevant under § 102(e) to claims 1, 2, and 10, and their dependents, provided the full text discloses (i) growth of a thick GaN layer on sapphire with a miscut in a specified direction in the 0.07°–20° window, and (ii) separation into a self-standing substrate with the recited off-orientation. I could not verify those internal details from the available search results; the examiner cited it (and the counterpart JP publication, item 10), which suggests it was considered close. It does not qualify under § 102(a)/(b) by publication date (published Sept. 2005, after the priority date), so the analysis rests on § 102(e).

10. JP 2005-298319 A (Sumitomo Electric Industries, Ltd.)

• Full citation: JP 2005-298319 A, "GaN single crystal substrate manufacturing method and GaN single crystal substrate," Sumitomo Electric Industries, Ltd.
• Filing date: 2004-03-17; published: 2005-10-27
• Description: Japanese counterpart of item 9 (same Sumitomo single-crystal GaN substrate manufacturing work).
• § 102 assessment: Published after the May 31, 2004 priority date, and a Japanese publication cannot receive a § 102(e) effective date from its JP filing. It is therefore not § 102 prior art against 7435608 under pre-AIA law (neither 102(a)/(b) by date nor 102(e) because it is not a U.S. patent/application publication). Treat the U.S. publication (item 9) as the operative reference from this family.

Family-cited references (cited in family members, not necessarily of record on the face of '608)

Google's family data also lists four "family-cites" that were cited in related family applications (JP 3669848 B2, JP 4691631 B2, JP 3929008 B2, and US 7,118,813 B2). Of these, the most substantively relevant is:

• US 7,118,813 B2 (Cree, Inc.), "Vicinal gallium nitride substrate for high quality homoepitaxy," filed 2003-11-14, granted 2006-10-10 — teaches a deliberately miscut ("vicinal") GaN substrate for improved homoepitaxial morphology. Because it issued/published after the 7435608 priority date and is directed to the substrate (used for homoepitaxy) rather than the sapphire-miscut manufacturing method of claims 1–15, it is not § 102 prior art of record against '608; it is context for the off-orientation rationale.

Non-patent literature cited (briefly, since "each citation" includes these on the face of the patent)

The examiner also placed five non-patent documents of record. None is a patent, so they are not § 102 "patented" references, but they can be § 102(a)/(b) printed publications:

• Nam et al., "Lateral epitaxy of low defect density GaN layers via organometallic vapor phase epitaxy," Appl. Phys. Lett. 71, 2638–2640 (Nov. 3, 1997) — ELO; background for dislocation reduction; no separated self-standing substrate claims teaching.
• Kuramoto et al., "Room-Temperature Continuous-Wave Operation of InGaN MQW-LDs Grown on an n-GaN Substrate with a Backside n-Contact," Jpn. J. Appl. Phys. 38, L184–L186 (Feb. 15, 1999) — FIELO/device art on an n-GaN substrate; not a sapphire-separation method.
• Zheleva et al., "Pendeo-Epitaxy — A New Approach for Lateral Growth of Gallium Nitride Structures," MRS Internet J. Nitride Semicond. Res. 4S1, G3.38 (1999) — pendeoepitaxy; background.
• Motoki et al., "Preparation of Large Freestanding GaN Substrates by HVPE Using GaAs as a Starting Substrate," Jpn. J. Appl. Phys. 40, L140–L143 (Feb. 15, 2001) — DEEP/freestanding GaN from GaAs; like JP 2003-165799 A, it is GaAs-based and therefore outside the sapphire-reciting independent claims.
• Oshima et al., "Preparation of Freestanding GaN Wafers by HVPE with Void-Assisted Separation," Jpn. J. Appl. Phys. 42, L1–L3 (Jan. 15, 2003) — VAS on sapphire; the closest non-patent analog to the manufacturing route of claims 1/2/10, but again no disclosed direction-specific 0.07°–20° miscut-to-off-orientation correlation is evidenced in the available record.

Bottom line on "most relevant prior art"

1. Strongest for the claimed method (claims 1, 2, 10 + dependents): the VAS family — US 2002/0197825 A1 (Usui) and JP 2003-178984 A (NEC) — because they combine sapphire growth with void-assisted separation into a freestanding III-V nitride substrate, plus US 2005/0208687 A1 (Sumitomo, § 102(e) date 2004-03-17), whose full text should be checked element-by-element.
2. Strongest for the off-orientation concept (mostly § 103): JP 2000-223743 A, US 2003/0205717 A1, and (family-cited) US 7,118,813 B2.
3. True § 102 anticipation of any claim is not affirmatively established on the available record for any cited reference, because the record does not confirm that any of them discloses the complete combination — sapphire miscut of 0.07°–20° in the specific m- or a-axis direction, growth, separation, and the resulting substrate off-orientation in the orthogonal axis — that the independent claims require.

Confidence caveats: I verified the '608 claim language, dates, assignment chain, and citation lists from the authoritative full text and USPTO/Google records. I could not fully verify the internal disclosures of the Japanese-language references (items 2, 3, 6, 7, 10) or the precise miscut disclosures of the Sumitomo and Usui publications from the search results available to me in this session. Before any anticipation rejection is advanced or relied upon, those full texts should be pulled from the USPTO Global Dossier/PAIR and compared claim-by-claim.

I'll analyze the obviousness of US 7,435,608 under § 103. First, let me verify the technical content of several key prior-art references cited in the patent so the combination analysis is grounded in what each reference actually discloses.

Let me verify additional key references, including the Rohm patent, the co-owned Hitachi Cable application, the Sumitomo GaN-substrate application, and the Cree vicinal GaN substrate patent.

Obviousness Analysis of US 7,435,608 (III-V Group Nitride System Semiconductor Self-Standing Substrate)

1. Scope, legal framework, and level of ordinary skill

US 7,435,608 (the "'608 patent") issued October 14, 2008, from divisional application US 11/589,771, which claims priority to US 10/928,739 (filed Aug. 30, 2004, abandoned) and Japanese application 2004-162189 (filed May 31, 2004). It was therefore examined under pre-AIA 35 U.S.C. § 103 and the Graham factors, as refined by KSR Int'l Co. v. Teleflex Inc. (2007): a claim is obvious if the differences between it and the prior art are such that the claimed subject matter as a whole would have been obvious to a person having ordinary skill in the art (PHOSITA), considering that a combination of familiar elements according to known methods that yields predictable results is likely obvious, and that "obvious to try" applies where a finite number of identified, predictable solutions exists.

A PHOSITA here would be a crystal-growth or epitaxy engineer with a graduate degree and several years' experience in III-V nitride (GaN/AlGaN/InGaN) epitaxy by MOVPE/HVPE, familiar with sapphire–GaN crystallography, dislocation-reduction techniques (ELO, pendeoepitaxy, VAS, DEEP), and the fabrication of freestanding GaN substrates for laser-diode applications. (The patent expired in 2020 for non-payment of maintenance fees; that is irrelevant to the merits but means this is a pure technical-validity question.)

2. The claimed invention in brief

• Claim 1 — method of making a self-standing III-V nitride substrate for a semiconductor laser by: providing a sapphire hetero-substrate off-oriented 0.07°–20° in the m-axis from C-face; growing an epitaxial III-V nitride single-crystal layer; separating it to obtain a self-standing substrate with a predetermined off-orientation in the a-axis.
• Claim 2 — identical, but sapphire off-oriented in the a-axis yielding a GaN off-orientation in the m-axis.
• Claims 3–9, 11–15 — dependent limitations (resulting GaN off-angle of 0.09°–24°; the 0.8–1.5× off-angle transfer ratio; sapphire off 1°–20°; InₓGaᵧAl₁₋ₓ₋ᵧN composition; in-plane dispersion within ±1°; thickness 200 µm–1 mm).
• Claim 10 — method of making a wafer by the same substrate-making steps followed by homo-epitaxial growth of a III-V nitride layer on the off-oriented self-standing substrate.

3. Prior-art map (from the patent's own citation record)

All references below appear in the "Patent Citations," "Family Cites," or "Non-Patent Citations" sections of the '608 record and pre-date the effective filing date:

4. Primary combination rendering claims 1 and 2 obvious

Proposed combination: Khare (US20030205717A1/US 6,576,932) in view of Usui (US20020197825A1 / JP2003178984A), Nichia (JPH11251253A), Oshima et al. (JJAP 42, L1 (2003)) and Kuramoto et al. (JJAP 38, L184 (1999)), optionally further in view of Cree (US7118813B2).

Element-by-element mapping (claim 1):

1. "Providing a sapphire substrate off-oriented 0.07°–20° in the m-axis from C-face." — Khare expressly teaches growing III-nitride layers on sapphire substrates intentionally misaligned from the c-plane, with misorientation angles from 0.05° up to ~10° — a range that substantially overlaps the claimed 0.07°–20° window (and encompasses the claimed 0.07°–0.2° lower region and the 1°–20° sub-range of claims 7–8). The choice of the m-axis (or a-axis) as the off-cut direction is not inventive: these are the only two low-index in-plane directions of hexagonal sapphire, and Khare's own figures identify the a/c/m planes of sapphire. Selecting one of two known off-cut directions, with the other direction claimed in mirror-image claim 2, is a design choice among a finite set, not a patentable distinction.
2. "Growing an epitaxial layer of III-V nitride single crystal." — Routine MOVPE/HVPE growth on sapphire, taught by Khare, Usui, Nichia, and the Rohm reference.
3. "Separating the epitaxial layer to obtain a self-standing substrate." — Usui (VAS), Nichia (etch-removal of sapphire) and Oshima et al. all disclose growing a thick GaN layer on sapphire and separating it to obtain a freestanding GaN substrate. Indeed, the '608 specification itself treats VAS and DEEP as known art (citing JP 2003-178984 and JP 2003-165799) and admits the general ELO-etch approach of JPH11251253A.
4. "Predetermined off-orientation in the a-axis [GaN]." — This is a crystallographic inevitability, not an invention. As the '608 itself states in its Background/FIG. 1 discussion, GaN (0001) grows on sapphire (0001) with the fixed in-plane relationship GaN ⟨11-20⟩ ∥ sapphire ⟨1-100⟩ (a 30° in-plane rotation). Therefore, an m-axis off-cut sapphire wafer necessarily produces an a-axis off-cut GaN crystal, and an a-axis off-cut sapphire wafer necessarily produces an m-axis off-cut GaN crystal. Claims 1 and 2 are nothing more than the two permutations of this known orientation relationship, which is why the '608 teaches both pairings as a matter of course.
5. "For a semiconductor laser." — A non-structural intended-use limitation. Kuramoto et al. (1999) already demonstrated InGaN MQW laser diodes grown on n-GaN substrates; the '608 Background likewise treats nitride laser devices as known. Intended use for a known purpose does not patentably distinguish a method whose steps and product are otherwise conventional.

Motivation to combine — the heart of the § 103 inquiry. The prior art supplied every reason a PHOSITA would need:

• Known problem: Freestanding GaN substrates could not be sliced from bulk boules (bulk GaN growth was impractical — stated in Usui and conceded in the '608 Background), so the only way to impart a controlled surface orientation to a freestanding GaN substrate was through the orientation of the hetero-substrate. Usui's entire project was making a usable freestanding GaN substrate with controlled properties, and Khare taught that off-cut sapphire improves epitaxial layer quality while its thick base layer is robust enough for substrate removal.
• Known benefit of off-cut substrates: By the priority date, off-axis (vicinal) substrates were the standard remedy for rough morphology/step-bunching in compound-semiconductor epitaxy generally (the '608 Background describes the GaAs practice of 0–20° off-cuts toward ⟨110⟩) and for III-nitrides specifically (Khare's misoriented sapphire for improved morphology and brightness; Cree's US7118813 teaching vicinal GaN substrates for high-quality homoepitaxy; the '608's own admission that off-orientation is "thought" of to flatten epi-layers).
• Predictable result / obvious to try: The inventor's own data (Figure 5 and the specification's admission that the grown off-angle is a linear 0.8–1.5× function of the sapphire off-angle) confirm the result is predictable and requires only routine X-ray characterization and ordinary process tuning. Choosing a sapphire off-cut in the range where (a) the GaN remains single-crystalline (≤20°) and (b) the resulting GaN off-angle suppresses hillock formation (≥0.09°, i.e., sapphire ≥~0.07°) is routine optimization within a finite, identified parameter space — squarely the KSR "obvious to try" scenario. Khare's disclosed 0.05°–10° misalignment already occupies most of that space.

Rebuttal of likely counterarguments:

• "No reference combines off-cut sapphire with freestanding-substrate separation." — § 103 does not require a single reference. The combination is of two mature, complementary bodies of art (off-cut sapphire epitaxy + freestanding GaN manufacture), each solving a distinct, known problem whose union is compelled by the fact that boule-slicing is unavailable for GaN.
• "The a-axis/m-axis mapping is not taught." — It is inherent in the well-known sapphire–GaN epitaxial orientation relationship, which the '608 itself presents as background, and claims 1 and 2 (covering both permutations) demonstrate the axis choice carries no inventive weight.
• "The ranges are critical." — The specification explains both endpoints in terms of ordinary physical limits (polycrystalline nucleation above ~20° sapphire off-cut; hillock-free homoepitaxy only above ~0.09° GaN off-angle; 0.8–1.5× transfer ratio). No unexpected results, criticality data, or comparative examples are provided. Ranges that merely optimize known parameters over a disclosed continuum are not inventive (In re Applied Materials, KSR).

5. Dependent claims 3–9, 11–15

These add only routine limitations that follow from the same combination:

• Claims 3/4 (resulting GaN off-orientation 0.09°–24°): Pure arithmetic on the known 0.8–1.5× transfer ratio applied to the claimed 0.07°–20° sapphire window (0.07 × 0.8 ≈ 0.06…; 20 × 1.2–1.5 = 24–30°, hence the 24° cap). The lower 0.09° bound is simply the empirical hillock-suppression threshold — the exact problem off-cut substrates were already known to solve (Cree; Khare).
• Claims 5/6 (0.8–1.5× linear relation): The specification presents this as the observed mechanism used to select the sapphire off-angle, i.e., an inherent property of epitaxial off-cut transfer, not a separate inventive step.
• Claims 7/8 (sapphire off 1°–20°): A narrower sub-range within Khare's disclosed envelope (Khare's ~10° upper bound overlaps; 1° is unremarkable).
• Claims 9/13 (InₓGaᵧAl₁₋ₓ₋ᵧN): The standard III-V nitride compositional formula; the specification identifies GaN and AlGaN as the merely preferred species.
• Claims 11/12 (in-plane off-angle dispersion within ±1°): A standard wafer-tolerance specification, and one that Usui's VAS process was expressly designed to satisfy (his objective was a low-warp freestanding substrate); the '608 admits bow-induced dispersion is "not so large…in view of practical substrate manufacture."
• Claims 14/15 (thickness 200 µm–1 mm): The specification itself explains these are mechanical constraints — ≥200 µm for self-support/handling and ≤1 mm for cleaving laser facets. Freestanding HVPE GaN wafers of exactly this thickness were produced by Oshima et al. and Usui.

6. Claim 10 (the wafer method)

Claim 10 adds only the step of homo-epitaxially growing a III-V nitride layer on the off-oriented self-standing substrate. That step was independently known and motivated: Cree's US7118813B2 exists precisely to enable high-quality homoepitaxy on vicinal GaN substrates, and Kuramoto et al. (1999) grew full InGaN MQW laser structures homo-epitaxially on n-GaN substrates. The '608's own Example 2 is an unremarkable MOVPE GaN-on-GaN growth. A PHOSITA following the Khare + Usui combination to obtain an off-oriented freestanding GaN substrate would, as a matter of course, grow the device layer on it — claim 10 is the obvious end-use of claims 1–2's product.

7. Additional, potentially closer references

The examiner-cited US20050093003A1 (Hitachi Cable, filed 2003-10-29) and US20050208687A1 / JP2005298319A (Sumitomo Electric, filed 2004-03-17) are both earlier-filed than the '608 family's first U.S. filing (Aug. 30, 2004) and would qualify as § 102(e) prior art for § 103 purposes. Either may disclose, more specifically than Khare, the manufacture of off-oriented GaN substrates/sapphire off-cuts. (Caveat: the Hitachi Cable reference is commonly owned and possibly same-inventor, which could implicate pre-AIA § 103(c) for that reference alone; the combination analysis above does not depend on it.)

8. Secondary considerations

No credible secondary considerations appear in the record: the specification shows no unexpected results, no comparative data establishing criticality of the endpoints, no long-felt need solved (off-cut substrates were already the industry remedy for morphology), and no industry skepticism or licensing acclaim. The rapid, parallel appearance of off-oriented freestanding GaN substrate art (Cree, Sumitomo, Mitsubishi Chemical, Seoul Opto Device, all citing or cited against the '608) is consistent with the technology being an obvious design step rather than a breakthrough.

9. Conclusion

Claims 1 and 2 of US 7,435,608 would very likely have been obvious under pre-AIA § 103 as the predictable combination of (i) off-cut sapphire substrates for improved III-nitride epitaxy (Khare US20030205717A1/US 6,576,932, misalignment 0.05°–10° from c-plane), (ii) known methods of making freestanding GaN substrates by thick HVPE growth on sapphire followed by separation (Usui US20020197825A1/JP2003178984A (VAS), Nichia JPH11251253A, Oshima et al. JJAP 42, L1 (2003)), and (iii) the known use of GaN substrates for semiconductor lasers (Kuramoto et al. JJAP 38, L184 (1999)) and of vicinal GaN for homoepitaxy (Cree US7118813B2). The a-axis/m-axis direction pairing is an inherent consequence of the textbook sapphire–GaN epitaxial orientation relationship, and the numeric ranges are routine optimization of known physical limits (single-crystal stability and hillock suppression), with the patentee's own linear 0.8–1.5× transfer data confirming predictability. Dependent claims 3–9, 11–15 add only obvious sub-ranges, tolerances, standard compositions, and mechanical thickness constraints; claim 10 merely appends the known homo-epitaxial growth step. The strongest validity argument available to the patentee would be the absence of any single reference expressly disclosing an m-axis-off sapphire substrate used to make an a-axis-off freestanding GaN substrate — but under KSR that is a combination of known elements with predictable results, not an inventive concept.

Note on sourcing: I verified the substantive disclosures of Khare (US20030205717A1) and Usui (US20020197825A1) via live search (patents.google.com/patent/US20030205717 and patentimages.storage.googleapis.com/.../US20020197825A1.pdf) and relied on the '608 specification's own Background statements for JPH11251253A, JP2003165799A, and the Oshima/Motoki/Kuramoto/Nam/Zheleva non-patent literature. I could not independently verify the internal disclosures of JP2000223743A, US20050093003A1, US20050208687A1, or US7118813B2 within the search budget; those are characterized only to the level of their titles and citation status, and the primary combination does not depend on them.