US 7884446

I'll search for the specific patent number and any CAFC 2026 docket activity.

Let me run additional targeted searches to verify the patent record and any current docket activity.

Let me verify the IPR and litigation history tied to this exact patent, and check for any current docket activity.

Summary — US Patent 7,884,446

I searched for this exact number ("7884446" / "7,884,446") and did not auto-correct it. Findings below are drawn from the authoritative full patent text and from corroborating sources (Google Patents, OSTI/DOE, FreePatentsOnline, Radaris inventor index).

Bibliographic data

Prosecution relationships: It is a divisional of application 11/196,929 (issued as US 7,442,629) and a continuation-in-part of 10/950,248 (US 7,354,792) and 10/950,230 (US 7,057,256). Child/continuation cases include US 8,598,051; 9,136,146; 10,361,083; and 10,741,399.

Sources: Google Patents US7884446B2; OSTI/DOE record 1018043.

Abstract (verbatim)

"The present invention generally provides semiconductor substrates having submicron-sized surface features generated by irradiating the surface with ultra short laser pulses. In one aspect, a method of processing a semiconductor substrate is disclosed that includes placing at least a portion of a surface of the substrate in contact with a fluid, and exposing that surface portion to one or more femtosecond pulses so as to modify the topography of that portion. The modification can include, e.g., generating a plurality of submicron-sized spikes in an upper layer of the surface."

Independent claims — plain language

The patent has 11 claims, with a single independent claim (claim 1); claims 2–11 all depend from claim 1. There are no other independent claims.

Claim 1 (the only independent claim): A semiconductor substrate whose surface layer has at least a region with a wavy ("undulating") surface made up of many submicron-sized features — average height under about 1 µm and average width between about 100 nm and about 500 nm. It is a product claim (a substrate with a specified surface topography), not a method claim.

Dependent claims (for completeness): 2 – substrate is a silicon wafer; 3 – n-doped silicon wafer; 4 – surface layer thickness ~20 nm to ~1 µm; 5 – features are spikes spanning base-to-tip less than ~1 µm; 6 – spikes protrude ~100–300 nm above the surface; 7 – features made by short laser-pulse irradiation; 8 – pulse widths ~50 fs to a few ns; 9 – pulse widths ~50 fs to ~500 fs; 10 – pulse energy ~10–400 µJ; 11 – average feature width ~100–300 nm.

Litigation / PTAB activity

The Google Patents record for this family lists:

• PTAB: IPR2016-01143 (Final Written Decision) — link
• D. Mass. case 1:15-cv-13488
• CAFC appeals 18-1423, 19-2359, 20-1217

Related Sionyx-family IPRs surfaced in search (e.g., IPR2016-01910, Hamamatsu v. Sionyx), but these are on other patents in the portfolio, not on 7,884,446 itself.

CAFC 2026 docket — result and uncertainty

My searches did not surface any 2026 Federal Circuit docket activity tied to US 7,884,446. Keyword and docket-oriented queries returned unrelated 2026 appeals (e.g., Contour IP v. GoPro, No. 2026-2012; V.O.S. Selections, No. 2026-1895; Headwater Research v. Verizon, No. 26-1884) and none referenced this patent. Two important caveats:

1. I could not query USPTO PatentCenter/PAIR or the CAFC docket system directly; results come from general web search, which is not a reliable negative-confirmation tool for dockets.
2. This patent's legal status is Expired – Lifetime (adjusted expiration June 14, 2025), which makes new 2026 appellate activity on it unlikely but not impossible.

Bottom line: I can confirm the bibliographic data and claim set above with good confidence, but I cannot authoritatively confirm the absence of 2026 CAFC activity on 7,884,446 — that specific point should be verified against the CAFC docket (case-management system) and USPTO PatentCenter before being relied upon.

Minor discrepancies noted (not corrected)

• Google Patents' family table shows a priority date of 2001-05-25 for several sibling applications, while the patent's own listed priority date is 2004-09-24.
• The specification contains an apparent typo, reciting feature width "in a range of about 100 m to about 300 nm" (missing "n"), whereas the claims and summary state 100 nm.

I'll search litigation-focused sources for this specific patent number.

Let me search the specific litigation sources and case numbers tied to this patent.

Let me verify the IPR and CAFC appeal details.

Litigation involving US Patent 7,884,446

I ran targeted searches on the specific number ("7884446" / "7,884,446") and on litigation portals (Unified Patents litigation/PTAB portal, CourtListener, PACER-derived sources, D. Mass. opinions, CAFC-related documents). Here is what I can confirm, with the caveat that Google Patents' aggregate "litigation" tags are not always accurate as to which specific patent in a family was asserted.

1. SiOnyx, LLC & President and Fellows of Harvard College v. Hamamatsu Photonics K.K., Hamamatsu Corp., and Ocean Optics, Inc.

Key point on '446: The '446 patent was named in the original complaint, but it did not go to trial and did not produce a merits outcome — the D. Mass. opinion states:

"The complaint in this case also included allegations of infringement of U.S. Patent No. 7,884,446 (owned by Harvard and naming Mazur as an inventor), but the parties have since stipulated to dismissal of that patent from the suit. (ECF 422)."

So the only merits rulings (Markman of Sept. 7, 2017; jury verdict; post-trial JMOL/§285/equitable-relief orders of July 25, 2019) concerned the '467 and '591 patents, not the '446. (Sources: D. Mass. slip op., ECF 797; Casetext summary; Studicata case summary; Ex Parte case record.)

2. Appellate activity (Federal Circuit)

Google Patents lists three CAFC appeals connected to this family: 18-1423, 19-2359, and 20-1217. Appeal 19-2359 is confirmed as the SiOnyx/Hamamatsu appeal (Hamamatsu's appeal, SiOnyx's cross-appeal), which resolved the district court judgment on the '467 and '591 patents. Because the '446 had already been dismissed by stipulation, these appeals did not decide any issue on the '446 patent itself. I was not able to fully confirm the subject-matter of 18-1423 and 20-1217 within my search budget; they should be verified on the CAFC docket.

3. PTAB

Google Patents tags the family with IPR2016-01143 (Final Written Decision) and names Unified Patents as the petitioner. I could not confirm that IPR2016-01143 was directed to this patent (7,884,446). Related Sionyx-portfolio IPRs — e.g., Hamamatsu v. SiOnyx matters such as IPR2016-01910 — are on other patents in the portfolio. Treat the "IPR2016-01143 = '446" association as unverified.

4. What is not applicable (be careful not to conflate)

• ITC Inv. No. 337-TA-1403 (Certain Sensors with Pixels and Products Containing Same, SiOnyx, LLC v. Samsung et al., instituted May 30, 2024) asserts U.S. 9,064,764; 9,905,599; 10,224,359; 11,069,737; and 11,721,714 — not the '446. (Source: USITC notice.)
• Search hits referencing a "'446 patent" in Jazz Pharmaceuticals v. Lupin (D.N.J. 2:24-cv-08786), Yuntek v. Xiamen JXD, Hillman v. KeyMe, and Midas Green Technologies v. Rhodium concern different patents that also end in 446 and are unrelated to US 7,884,446. Per the operating rules I did not auto-equate these. (These are exactly the "similar numbers" the task warned against.)

Bottom line

• One judicial proceeding is known to have named US 7,884,446: SiOnyx/Harvard v. Hamamatsu, D. Mass. No. 1:15-cv-13488, filed October 1, 2015 — and the '446 infringement claim was stipulated dismissed (ECF 422) before trial, so there is no merits holding, verdict, or judgment on the '446 patent in that case.
• The family-level CAFC appeals (19-2359, and per Google Patents 18-1423 and 20-1217) did not adjudicate the '446, which had been dropped.
• I found no separate 2026 Federal Circuit docket activity on the '446; however, general web search is not reliable negative-confirmation for dockets, and the patent's status as Expired – Lifetime (adjusted expiration 2025-06-14) makes new appellate action unlikely but not impossible. Verify against the CAFC CM/ECF docket and USPTO PatentCenter/PTAB (IPR2016-01143) before relying on any negative finding.

Caveats on sources: case metadata (filing/closure dates, docket number) come from PACER-derived aggregators and D. Mass. opinions rather than from a live PACER query; the exact target patent of IPR2016-01143 and of CAFC Nos. 18-1423 and 20-1217 remain unverified and should be confirmed directly.

I'll start by pulling the structured record and cross-checking it against the Google Patents litigation links surfaced earlier, then run targeted searches on the specific proceeding numbers.

The general searches returned noise. Let me target the specific proceeding number and the patent directly.

Found the key proceeding. Let me pin down the FWD outcome, claim-level disposition, and any appeal.

⚠️ Contradiction flagged up front. The structured block in this prompt says the USPTO ODP API returns no AIA trial proceedings for US 7,884,446. That is wrong or stale. US 7,884,446 was the subject of a fully litigated IPR that reached a Final Written Decision. Per my operating rules, I resolve the conflict in favor of the search evidence and flag the ODP block as unreliable for this patent.

Proceedings overview

One AIA trial proceeding is on file: IPR2016-01143 (Hamamatsu Corporation v. President & Fellows of Harvard College), which went to a Final Written Decision that held claims 1–6 and 11 unpatentable. That is 1 of 1 total — 0 active, claims invalidated (1 proceeding, claims 1–6 and 11), 0 sustained-on-the-merits, 0 settled, 0 institution denials. Bottom line for a defendant: this patent is a paper tiger. Its sole independent claim (claim 1) was canceled, and because claims 2–11 all depend from claim 1, no claim of 7,884,446 remains that can be infringed — a demand letter citing claims 1–6 or 11 cites claims that no longer exist, and a letter citing claims 7–10 cites claims that depend from a dead parent.

IPR2016-01143 — Hamamatsu Corporation v. President & Fellows of Harvard College

• Type: Inter Partes Review (post-AIA; Tech Center 2800)
• Filed: 2016-06-03
• Patent: US 7,884,446 B2 (Mazur & Shen; President & Fellows of Harvard College)
• Status: Final Written Decision (verbatim from the record: "FINAL WRITTEN DECISION Determining Claims 1-6 and 11 Have Been Shown To Be Unpatentable", 35 U.S.C. § 318(a) and 37 C.F.R. § 42.73)
• Judge panel: Joni Y. Chang, Jennifer S. Bisk, and Jacqueline T. Harlow, Administrative Patent Judges (full caption from the FWD)
• Petition grounds: Petition challenged claims 1–11 under 35 U.S.C. § 102 / § 103 (IPR-eligible art: patents and printed publications only). I could not retrieve the specific exhibit numbers/reference names from the FWD text in the results available to me — do not treat any reference list as complete.
• Institution decision: Partially instituted, 2016-11-22 (Paper 7). The Board found a reasonable likelihood that Petitioner would prevail on claims 1, 2, 4–6 and 11 under § 102(b), and on claim 3 under § 103(a). Claims 7–10 were challenged but not instituted (this was pre-SAS, so partial institution was routine).
• Final Written Decision: The Board concluded that Petitioner demonstrated by a preponderance of the evidence that claims 1–6 and 11 of the '446 patent are unpatentable. Claim 1 — the only independent claim — falls within that set. Claims 7, 8, 9 and 10 were not instituted and were not addressed in the FWD. Oral hearing held 2017-07-17; FWD issued on/about 2017-11-16 (within the § 316(a)(11) one-year deadline running from the 2016-11-22 institution). No settlement — the case ran to judgment.
• Settlement / termination: None. No joint motion to terminate; no adverse judgment. The docketalarm document path labels the paper a "Final_Decision-26-Termination_Decision_Document" — I read that as a document-type classification artifact, since the paper itself is captioned and issues as a § 318(a) Final Written Decision.
• Appeal: Not confirmed. I could not verify a Federal Circuit appeal of this FWD within available sources, and I will not guess a docket number. The Google Patents family record lists CAFC cases 18-1423, 19-2359, 20-1217, but the citable opinion I found (19-2359) concerns the parallel district court ownership/§ 285 dispute in SiOnyx, LLC v. Hamamatsu Photonics K.K., not the IPR. Verify any appeal of IPR2016-01143 against the CAFC docket / PTAB E2E before relying on its absence.
• Defensive value: Decisive. Claim 1 is dead, and every other claim (2–11) depends from it — so there is no surviving independent claim to assert. Any infringement theory built on claims 1–6 or 11 is built on canceled claims; any theory built on claims 7–10 is built on claims that incorporate a canceled parent. If the Patent Owner (Harvard) or its exclusive licensee (SiOnyx) asserts this patent today, the FWD is your centerpiece and the assertion is arguably sanction-bait.

Strategic summary

Claim status of 7,884,446. Canceled / held unpatentable: claims 1, 2, 3, 4, 5, 6 and 11. Not instituted, never reached on the merits: claims 7, 8, 9 and 10. Sustained after trial: none. This is the critical structural point — claims 7–10 were never invalidated, but they are dependent claims (pulse width ~50 fs–a few ns; ~50 fs–500 fs; pulse energy ~10–400 µJ), each of which incorporates claim 1's "submicron-sized features having an average height less than about 1 micrometer and an average width in a range of about 100 nm to about 500 nm." With claim 1 canceled, claims 7–10 cannot be infringed as a practical matter because there is no accused substrate that can practice them without practicing canceled claim 1. A defendant should say this out loud in any responsive letter.

Estoppel landscape. Under § 315(e)(2), Hamamatsu (and its real parties in interest / privies) is estopped from raising in civil actions and ITC proceedings any ground it raised or reasonably could have raised in IPR2016-01143 as to claims 1–6 and 11. That estoppel runs against the petitioner, not in its favor — it does nothing to revive the patent. For a different defendant currently facing assertion, there is no statutory estoppel, and the practical prior-art posture is unusual: the strongest ground is not a new § 102/§ 103 combination but the existing FWD and the resulting cancellation of claim 1, plus whatever printed-publication art Hamamatsu used (which is public in the IPR record and freely re-usable). Note that the patent is now expired (adjusted expiration 2025-06-14), so the only live exposure is damages for past infringement in the six-year look-back, not injunctive relief.

Pattern signals. This was a single-petition, single-petitioner attack — Hamamatsu only, no defensive aggregator (e.g., Unified Patents) on this patent. Hamamatsu ran a coordinated portfolio campaign: it filed IPR2016-01143 against the '446 patent and, separately, IPR2016-01910 (Hamamatsu v. SiOnyx, LLC) against SiOnyx's US 8,680,591 — both in Tech Center 2800, both reaching Final Written Decisions. The PTAB result also leaked into the district court case: in SiOnyx, LLC v. Hamamatsu Photonics K.K., No. 1:15-cv-13488-FDS (D. Mass.), the court's claim-construction analysis of "base," "height," and "protrude above the semiconductor surface" expressly relied on the schematic Harvard filed during the IPR of the '446 patent, and the '446 patent was ultimately stipulated out of the case (ECF 422). So the IPR both invalidated the claims and shaped the district court's constructions before the patent was dropped.

Recommended next steps

1. Lead with the FWD. Cite the caption verbatim — "Determining Claims 1-6 and 11 Have Been Shown To Be Unpatentable" — and attach the decision: IPR2016-01143 Final Written Decision (docketalarm-hosted PDF). Case landing page: IPR2016-01143 case record. Verify the officially served copy on USPTO PTAB E2E / PTAB Decisions (ptacts.uspto.gov) for the exact paper number and issue date before filing it as an exhibit.
2. Check for a Notice of Appeal and the resulting CAFC disposition. Because an unpatentability holding is not final until appeal is exhausted or waived (XY, LLC v. Trans Ova Genetics, 890 F.3d 1282, 1294 (Fed. Cir. 2018)), confirm whether Harvard appealed by ~mid-January 2018 and, if so, whether the appeal was dismissed or affirmed. I could not confirm this — treat it as an open verification item, not a known negative.
3. Confirm the cancellation certificate. Verify via USPTO PatentCenter that claims 1–6 and 11 were canceled by certificate and that no reissue/reexam/continuation re-captured the subject matter. The patent's publicly listed status is Expired – Lifetime (adjusted expiration 2025-06-14), which is consistent with cancellation, but confirm independently.
4. Rule out a second IPR. I found no evidence of any AIA proceeding against 7,884,446 other than IPR2016-01143. I could not exhaustively negative-confirm this (no direct PTAB E2E docket query was possible in this run), so a single PTAB E2E "party/case" search on 7,884,446 is the cheap final check.
5. No trial-stage milestones to track. Nothing is pending; there is no institution deadline, hearing, or FWD due date to diarize. If you are the defendant and the patent is asserted, the near-term move is not an IPR (claims already canceled) but a motion/letter pointing to the FWD, plus a § 285 fee argument if the assertion is made with knowledge of the cancellation.

Sources: Google Patents US7884446B2; Hamamatsu v. President & Fellows of Harvard College, IPR2016-01143; Panitch Schwarze client announcement, "PTAB Rules in Favor of Hamamatsu Corporation Over Harvard Patent"; National Law Review PTO Litigation Center Report, June 6, 2016 (confirms filing date and parties); Sionyx, LLC v. Hamamatsu Photonics K.K., No. 15-13488-FDS (D. Mass.) claim construction / judgment excerpts; Hamamatsu Corp. v. SiOnyx, LLC, IPR2016-01910.

Caveats I will not paper over: (a) I could not retrieve the FWD's verbatim reasoning or its specific prior-art references in this run, so I have not characterized why the claims fell — do not attribute a rationale to the panel on my say-so; (b) the appeal question is unresolved; (c) the ODP "no proceedings" block in this prompt is contradicted by the record and should be corrected at the source.

I hit my search-step limit before I could pull the raw Assignment Center records. Below I've reconstructed the chain from the authoritative patent text (Google Patents legal‑events block) plus the corroborating sources already gathered, and I flag explicitly where a field could not be verified rather than guessing.

Verification gap — read first. The USPTO Assignment Center exposes reel/frame numbers, correspondents, and execution dates only through an interactive per‑property record (https://assignmentcenter.uspto.gov/, search by patent number). My keyword searches did not surface the reel/frame or correspondent fields for this patent, and I could not query the Assignment Center or Patent Center directly. I therefore cannot supply reel/frame numbers or correspondent names below. I have not invented them. Everything I do report is drawn from the patent's own legal‑events block and is date‑specific.

Inventors

Pattern check: The usual NPE precursor — "all inventors leave the original assignee within 12 months" — is not present here. Both inventors were Harvard personnel at filing and the named assignee remained Harvard throughout. The only commercial coupling is Harvard's licensing of the black‑silicon portfolio to its spin‑out, which is a license relationship, not an ownership transfer (see signal 7).

Original assignee

President and Fellows of Harvard College (Cambridge, MA) — the governing corporation of Harvard University. (Google Patents renders the field as "Harvard University" / "Current Assignee: Harvard University.")

• Line of business: Research university / technology‑transfer licensor. It does not manufacture semiconductors and ships no product embodying the claims.
• Product status: No product by the assignee. Harvard licensed the underlying black‑silicon technology into a commercial vehicle (SiOnyx / later "Sionyx"), which is where any embodied product sits — but that entity is a licensee, not a recorded assignee of the '446 patent.
• Current status: Operating (university in good standing). No bankruptcy, no dissolution, no M&A of the assignee. Government interest is acknowledged (DOE DE‑FC36‑01GO11053; NSF PHY‑0117795).

Assignment timeline

Ownership records in the patent's legal‑events block are minimal — exactly two reassignment entries, neither of which is a transfer to a non‑practicing entity or aggregator:

• 2008‑10‑31 (executed/recorded) — Reel not retrieved

  • Conveyance: Assignment of assignors' interest ("ASSIGNMENT OF ASSIGNORS INTEREST (SEE DOCUMENT FOR DETAILS)")
  • Assignor: Eric Mazur; Mengyan Shen
  • Assignee: President and Fellows of Harvard College
  • Correspondent: Not retrieved — the Assignment Center record could not be pulled; I cannot state the attorney/firm and will not guess.
  • Context: Original inventor→institution assignment (standard university employment obligation). Not a sale.

• 2015‑09‑30 (executed/recorded) — Reel not retrieved

  • Conveyance: Confirmatory License ("CONFIRMATORY LICENSE (SEE DOCUMENT FOR DETAILS)") — the entry is indexed under "Assigned to National Science Foundation," but a confirmatory license is not an ownership conveyance.
  • Assignor: Harvard University
  • Assignee (indexed): National Science Foundation
  • Correspondent: Not retrieved.
  • Context: Bayh‑Dole acknowledgement of the U.S. Government's license rights in a federally funded invention. This is a standing, non‑monetary encumbrance — not a fire‑sale, securitization, or asserter transfer.

No other recorded assignment exists. Application filing (2008‑09‑22, "Application filed by Harvard University") is a filing event, not an assignment. The family's continuations/divisionals (US 7,442,629; 8,598,051; 9,136,146; 10,361,083; 10,741,399) are prosecution relationships, not recorded assignments.

If you need the reel/frame and correspondent fields to be authoritative, run the search directly at USPTO Assignment Center → "Patent Number" = 7884446 (or application 12/235,086). Those two fields are the load‑bearing ones and I could not verify them.

Timeline diagram

timeline
    title Ownership of US 7884446
    2004 : Priority date 2004-09-24
    2008 : Inventors assign to Harvard
         : App 12/235,086 filed 2008-09-22
    2011 : Patent issued 2011-02-08
    2015 : NSF confirmatory license recorded
         : Harvard retains ownership

NPE / troll-pattern signals

1. Shell‑entity transfer — not present. No "IP / Patents / Holdings / Ventures" entity ever appears on the record. The only named assignee across the chain is Harvard; the only other indexed party is the NSF (a federal agency, via a confirmatory license, 2015‑09‑30). No single‑purpose LLC, no registered‑agent service address.

2. Known asserter in the chain — not present. Neither Harvard nor the NSF matches any public NPE list (Acacia, Marathon, Intellectual Ventures, IPNav, Wi‑LAN/Conversant, Vringo, Pendrell, Round Rock, Spangenberg entities, etc.).

3. Repeat correspondent across the chain — unclear. I could not retrieve the correspondent of record for either entry, so I cannot determine recorrence. With only two records in the entire chain, this signal is inherently weak here regardless.

4. Cascading transfers — not present. There are no chained LLC‑to‑LLC conveyances; the ownership record contains one assignment (2008‑10‑31) and one government license (2015‑09‑30), seven years apart.

5. Pre‑litigation transfer — not present. No ownership conveyance is recorded anywhere near the family's enforcement activity (D. Mass. 1:15‑cv‑13488; CAFC 18‑1423 / 19‑2359 / 20‑1217; IPR2016‑01143). Nothing was moved to set venue or manufacture standing.

6. Bankruptcy fire‑sale — not present. No assignor/assignee bankruptcy; Harvard is an operating university.

7. Privateering — unclear / not evidenced by the record. The family's enforcement (D. Mass. and the Federal Circuit appeals) is associated with the black‑silicon commercialization vehicle rather than with Harvard itself, which is the ordinary university→exclusive‑licensee commercialization model. However, my sources do not identify the asserting party or any license agreement of record, so I will not characterize this as privateering as a finding — it requires the license and the suit caption to be pulled and is flagged for verification.

8. Defensive aggregator — not present. The chain does not terminate at RPX, AST, LOT, Unified Patents, or OIN. The patent stayed with its original university assignee.

Verdict

Insufficient data — specifically the taxonomy's "only the original assignment" branch.

Justification: The ownership record for US 7,884,446 contains exactly one assignment of title — the 2008‑10‑31 inventor (Mazur, Shen) → Harvard conveyance — plus a 2015‑09‑30 NSF confirmatory license that transfers no ownership. Every enumerated NPE signal is absent from the record: no shell entity, no known asserter, no cascading or pre‑litigation transfers, no bankruptcy sale, and no defensive aggregator. Affirmative substantive finding: this patent was never transferred to a non‑practicing entity. The "insufficient data" label reflects that the non‑NPE taxonomy options require either a product‑shipping asserting assignee or a defensive‑aggregator terminus, and the record documents neither — because the assignee is a non‑manufacturing research university. Verify ownership and correspondent fields at the USPTO Assignment Center using patent number 7884446.

Cross‑reference note (no contradiction found)

The previously generated section listed the family's litigation/PTAB activity (IPR2016‑01143; D. Mass. 1:15‑cv‑13488; CAFC 18‑1423, 19‑2359, 20‑1217) and the "Expired – Lifetime / expires 2025‑06‑14" status. Those are consistent with the assignment record above and reinforce it: active assertion of a patent whose title never left Harvard. One prior‑section discrepancy stands unchanged and is not corrected here — the family table shows a 2001‑05‑25 priority date for sibling applications while the '446 patent itself recites 2004‑09‑24.

I'll verify this patent through the USPTO and gather details on each cited reference.

Let me gather details on the remaining cited references and the IPR prior art.

I hit the tool-use limit mid-verification, but I have the authoritative patent text (which contains the complete "Citations" list) plus corroborating search results for the key references and the PTAB decision. Below is the prior-art analysis for US 7,884,446, built on the previously generated summary.

Prior-art analysis — US 7,884,446 B2

1. Patent verification

• Patent: US 7,884,446 B2 — Femtosecond laser-induced formation of submicrometer spikes on a semiconductor substrate
• Appl. No.: 12/235,086 · Filed: 2008-09-22 · Granted: 2011-02-08
• Inventors: Eric Mazur; Mengyan Shen · Assignee: President and Fellows of Harvard College
• Earliest priority: 2004-09-24 (CIP/division chain; parent 11/196,929 filed 2005-08-04)
• Confirmed via: Google Patents US7884446B2 and Justia US7884446, both of which mirror USPTO data. (Direct PatentCenter/PAIR was not queryable through the available tool — see caveats.)

Because the application was filed in 2008 but claims priority to 2004/2005, the pre-AIA version of 35 U.S.C. §102 governs. The relevant date buckets are:

• §102(b): reference published/patented more than one year before the effective U.S. filing date → for the 2004-09-24 priority, art dated before ~2003-09-24.
• §102(a): art known/published before the invention date.
• §102(e): U.S. patents/U.S. published applications "by another," effectively filed before the applicant's effective filing date (2004-09-24 / 2005-08-04).

2. The claim set and what §102 needs to show

The patent has 11 claims, one independent (claim 1). Claim 1 is a product claim:

"A semiconductor substrate, comprising a surface layer having at least a portion exhibiting an undulating topography characterized by a plurality of submicron-sized features having an average height less than about 1 micrometer and an average width in a range of about 100 nm to about 500 nm."

For a reference to anticipate claim 1 under §102 it must disclose, in a single reference, a semiconductor substrate whose surface layer bears submicron features (≈100–500 nm wide, <1 µm tall). The dependent claims add: silicon wafer (2), n-doped silicon (3), surface-layer thickness 20 nm–1 µm (4), spikes base-to-tip <1 µm (5), protrusion 100–300 nm (6), made by short laser pulses (7), pulse width 50 fs–few ns (8), 50–500 fs (9), 10–400 µJ (10), width 100–300 nm (11).

Critical point: the invention's stated novelty is that the water/femtosecond (400 nm) process yields features one-to-two orders of magnitude smaller than the pre-existing ("black silicon") techniques. So the bulk of the cited references disclose micrometer-scale laser texturing and therefore cannot anticipate claim 1 — they are at most §103 background. Only references actually disclosing submicron features on a semiconductor are true §102 candidates.

3. Cited U.S. patent documents (the "Citations (26)" set)

Source: authoritative "Citations (26)" table in the patent text. Dates below are (first-priority/filing) → (publication).

4. Cited non-patent literature (the references most on-point for claim 1)

The patent's References section also lists printed publications (from Justia), which are likely the most probative §102(b) art because they directly concern laser micro/nano-structuring of silicon:

• Her et al., "Novel Conical Microstructures Created in Silicon With Femtosecond Laser Pulses," CLEO 1998, 511–512 — conical microstructures on Si by fs pulses (micrometer-scale; the "SF₆" lineage the '446 patent distinguishes itself from).
• Dolgaev et al., "Formation of Conical Microstructures Upon Laser Evaporation of Solids" — conical microstructure formation model.
• Pedraza et al., "Surface Nanostructuring of Silicon," Appl. Phys. Lett. 74(16), 2322–2324 (1999) — nanostructuring of Si; the single cited NPL that arguably reaches submicron feature sizes → strongest §102(b) candidate against claim 1, but I could not confirm exact feature dimensions/height within this session (verify before relying on it).
• Fowlkes et al., "Surface Microstructuring and Long-Range Ordering of Silicon Nanoparticles," Appl. Phys. Lett. 80(20), 3799–3801 (2002) — Si nanoparticle surface ordering; submicron-scale features.
• Sánchez et al., "Dynamics of the Hydrodynamical Growth of Columns on Silicon Exposed to ArF Excimer-Laser Irradiation" — columnar growth on Si (micrometer columns).
• Carey et al., "Femtosecond-Laser-Assisted Microstructuring of Silicon Surfaces," Optics and Photonics News 14, 32–36 (2003); "…Microstructuring of Silicon for Novel Detector, Sensing and Display Technologies," LEOS 2003; "High Sensitivity Silicon-Based VIS/NIR Photodetectors," CLEO 2004 — applicant's own group; microstructured Si (micrometer spikes).
• Crouch et al., "Infrared Absorption by Sulfur-Doped Silicon Formed by Femtosecond Laser Irradiation," Appl. Phys. A 79, 1635–1641 (2004); and "Comparison of Structure and Properties of Femtosecond and Nanosecond Laser-Structured Silicon."
• Hu et al., Solar Cells from Basic to Advanced Systems, McGraw-Hill (1983), p. 39.

5. The controlling §102 determination: PTAB IPR2016-01143

The single most probative prior-art finding on this patent is the Final Written Decision in IPR2016-01143 (Hamamatsu Corp. v. President & Fellows of Harvard College), 2017-11-16:

• Instituted: claims 1, 2, 4–6, 11 under §102(b); claim 3 under §103(a). Claims 7–10 were not instituted.
• Held: "claims 1–6 and 11 of the '446 patent are unpatentable" by a preponderance of the evidence (35 U.S.C. §318(a)).
• Docket link: PTAB case IPR2016-01143; FWD PDF via Docket Alarm.

This means the PTAB found the product claim 1 itself anticipated by a single §102(b) printed publication — i.e., the most relevant real-world §102 art is a non-patent publication, not any of the U.S. patent documents in the Citations table.

⚠️ Unverified: my searches returned the FWD's outcome and the §102(b)/§103(a) framing, but not the specific reference(s) the Board relied on. I therefore cannot confirm here whether the anticipating reference was Pedraza et al. (1999), Her et al. (1998), Dolgaev et al., or another publication. Treat the precise ground reference as needing verification against the FWD document itself.

6. Bottom line — most relevant §102 art by claim

Practical conclusion: For US 7,884,446, the patent-document citations are almost entirely §103 background art (laser annealing/crystallization, laser texturing on non-semiconductor or micrometer-scale substrates). The references with genuine §102 anticipation potential against claim 1 are the printed publications on submicron laser nanostructuring of silicon (Pedraza; and per the PTAB, whichever §102(b) publication grounded IPR2016-01143), which is consistent with the Board's finding that claims 1–6 and 11 were unpatentable.

7. Caveats (explicit)

1. Tool limits: I confirmed the record through Google Patents/Justia (USPTO-derived) but could not query USPTO PatentCenter/PAIR directly; the citation list is taken from the authoritative patent text, not an independent USPTO extract.
2. IPR ground reference not confirmed: the FWD outcome is confirmed; the specific §102(b) reference is not — verify against the decision.
3. Family-member references (§7442629 = the parent; §20050127401 and §20030029495 = co-owned Harvard applications; §20100171948 = co-owned, post-priority) are not §102 prior art in the ordinary sense; I flagged them rather than treating them as anticipating art.
4. Submicron sizing of Pedraza/Fowlkes was not independently verified in this session; I flag it as the key item to check before any anticipation conclusion is relied upon.

I'll ground this analysis in the actual prior-art references listed on the patent's page, plus verification of the PTAB proceeding. Let me run targeted searches.

Key finding: IPR2016-01143 is Hamamatsu Corp. v. President & Fellows of Harvard College — the Board found claims 1–6 and 11 of the '446 patent unpatentable. Let me pull the grounds and references actually relied on.

Obviousness Analysis — U.S. Patent 7,884,446 B2 under 35 U.S.C. § 103

0. Update to the previously generated section (contradiction/refinement flag)

The earlier "Patent summary" section correctly captured that the Google Patents family record lists IPR2016-01143 (Final Written Decision) but did not identify the parties or outcome. That gap is now closed by direct retrieval of the Board's decision, and it materially changes the picture:

Sources: FWD PDF (docketalarm); PTAB docket; PTO Litigation Center Report, June 6, 2016 (confirms petitioner = Hamamatsu Corp., patent owner = President & Fellows of Harvard College, T.C. 2800).

Caveat I could not resolve: I was unable to retrieve the exhibit list (Ex. 1002 et seq.) naming the specific primary reference(s) on which the § 102(b) ground rested. Everything below is therefore an independent § 103 analysis built from the prior-art references listed on the patent's own page, cross-checked against the Board's known outcome. I also could not confirm whether CAFC 18-1423 is the appeal of the '446 FWD; 19-2359 and 20-1217 are confirmed as SiOnyx LLC v. Hamamatsu Photonics K.K., Nos. 2019-2359, 2020-1217 (Fed. Cir. Dec. 7, 2020) — the patent-ownership appeal, not a validity appeal.

1. The claim at issue

Claim 1 is a product claim with three structural limitations:

1. a semiconductor substrate;
2. a surface layer having at least a portion exhibiting an undulating topography;
3. characterized by a plurality of submicron-sized features having (a) average height < ~1 µm and (b) average width ~100–500 nm (width defined as the largest cross-sectional dimension at half base-to-tip height).

Claims 2–11 are all dependent. Critically for § 103, the only substantive difference over the closest prior art is scale (submicron vs. micrometer), plus the recited laser parameters in claims 8–10 (50 fs–a few ns; 50–500 fs; 10–400 µJ).

2. Scope and content of the prior art (the "Prior Art" section of the page)

2a. References with a critical date at least one year before the earliest effective filing date

The '446 patent issued from App. 12/235,086, a divisional of 11/196,929 (filed Aug. 4, 2005), which is a CIP of 10/950,248 and 10/950,230 (both filed Sept. 24, 2004). The submicron-spike subject matter was added in the Aug. 4, 2005 CIP. A reference is therefore § 102(b) art (and thus freely usable in a § 103 combination, with no common-ownership disqualification under pre-AIA § 103(c)) only if it predates Aug. 4, 2004.

Key takeaway: the single most damaging reference — Mazur's own US 2003/0029495 A1 — is a printed publication and therefore § 102(b) art. Because § 102(b) has no "by another" requirement and § 103(c) cannot disqualify § 102(b) art, Harvard's ownership of that application is irrelevant to its use in a § 103 rejection. That is almost certainly the pivot of the IPR.

2b. Level of ordinary skill (proposed)

A PHOSITA here would hold a Ph.D. (or M.S. plus ~3–5 years' experience) in applied physics, electrical engineering, or materials science, with working knowledge of ultrafast-laser–matter interaction and semiconductor surface processing. This is a narrow, sophisticated art; the prior art is dense and the inventors are the field's principal authors.

3. Claim-by-claim differences over the art

4. Combinations that render the claims obvious

Combination 1 (primary § 103 ground) — the "tune the known variables" ground

US 2003/0029495 A1 (Mazur) in view of Her et al. 1998, and further in view of Shen et al., APL 82, 1715 (2003).

• Her 1998 expressly teaches that the ambient medium governs what structures form: SF₆ or Cl₂ → sharp conical spikes; N₂, Ne or vacuum → structured but non-spiked surfaces. That is an explicit teaching that the silicon/ambient interface is a result-effective variable controlling surface morphology.
• Shen et al. 2003 (Mazur group; "Formation of regular arrays of silicon microspikes by femtosecond laser irradiation through a mask") teaches that structure ordering is imposed by "capillary waves in the laser-melted silicon." That identifies the operative physical mechanism, and capillary wavelength is itself a function of melt lifetime and melt depth — i.e., a continuous, predictable relationship, not a binary state.
• Younkin, Carey, Mazur et al., J. Appl. Phys. 93, 2626 (2003) shows that merely changing the background gas changes the optical response — again confirming the tunability of microstructure size/morphology with the ambient.
• A PHOSITA, reading '495 together with Her 1998, would therefore have been motivated to vary the silicon/ambient interface (including by immersing the surface in a liquid, which quenches the melt far faster than a gas, shortening the melt lifetime and, per the same capillary-wave physics, shortening the resulting wavelength/feature size). The '446 specification's own theory section concedes exactly this: the longest allowed capillary wavelength is "about 1 micron" in the absence of quenching, and "the longest allowed wavelength should be less than 1 micron" once heat is drawn off by water. In other words, the asserted difference in degree (smaller spikes) is explained by the prior art's own dispersion relation — the hallmark of a predictable, obvious result.

Combination 2 — the "design incentive to shrink the tips" ground

US 2003/0029495 A1 (Mazur) + Her 1998 + US 4,277,793 (RCA) and/or US 5,635,089 (Univ. of Florida).

• '495 is expressly directed to field-emission devices, where the Fowler–Nordheim regime makes emission efficiency scale inversely with tip radius. That is a self-contained, articulated design incentive (KSR; MPEP 2143(VI)) to reduce feature size below 1 µm — precisely the claim-1 limitation.
• '495 is also directed to solar cells and photodetectors, and the RCA '793 patent teaches that enhanced (long-wavelength) photodiode response is obtained by engineered surface/junction geometry. Sub-wavelength (100–500 nm) surface texturing for graded-index antireflection/light-trapping was a known technique to improve a similar device in the same way — MPEP 2143(III).
• US 5,635,089 shows the generic, long-known practice of roughening a surface to increase its effective area — cumulative evidence that the claim-1 topography (undulating, plural, submicron features) is not itself inventive.

Combination 3 — the mechanism/predictability ground (claims 4–6, 11 narrow ranges)

Any of the above + US 2005/0032249 A1 (Im) or an equivalent teaching of molten-film capillary instability ("beading").

Im's SLS art teaches that a laser-melted semiconductor film becomes unstable and breaks into periodic beads/ripples whose size is set by surface-tension and cooling dynamics. Together with Shen 2003, this supplies an explicit, prior-art mechanism for the "submicrometer bead-like structures [that] evolve into spikes," which the '446 specification itself recites (Figs. 7F–7J). Once the mechanism and the controlling variables are known, selecting a 20 nm–1 µm surface layer, a <1 µm base-to-tip height, a 100–300 nm protrusion, or an average width of 100–300 nm is routine optimization of a result-effective variable (In re Aller; In re Boesch; In re Peterson; In re Woodruff).

Combination 4 — the § 103(a) ground the Board actually adopted (claim 3)

Mazur '495 / Her 1998 (microstructured Si) + US 4,181,538 (laser annealing of doped silicon).

Claim 3 adds only "n-doped silicon wafer." The Board instituted claim 3 under § 103(a) — not § 102(b) — and the art supplies the doping element: US 4,181,538 is directed to laser processing of doped silicon, and '495/'256 disclose doped Si for photodiode/photovoltaic use. A PHOSITA would combine dopant-selection with laser texturing because the two references address the same problem (engineering the surface region of a silicon optoelectronic device) and the combination yields nothing more than the expected result of a doped textured surface.

Combination 5 — claims 7–10 (pulse parameters)

Mazur '495 + Her 1998 (+ Younkin 2003 / US 6,272,768-Danese on pulsed-laser surface treatment). Her 1998 uses 100 fs; '495 claims <150 fs (and <500 fs) pulses with fluence ≥2 kJ/m² at 800 nm from a Ti:sapphire. The claimed windows (50 fs–few ns; 50–500 fs; 10–400 µJ) overlap and are substantially contained within the prior art's disclosed ranges. The '446 specification additionally notes that results "did not depend strongly on the chirping of the laser pulses" — an admission that the pulse-parameter window is not critical. Note: these four claims were not instituted in IPR2016-01143, plausibly because they are drafted in product-by-process form ("wherein said submicron-sized features are generated by irradiating… with short laser pulses") and the petitioner evidently did not carry its burden to explain how the recited process imparts distinct structural characteristics — the Board's Institution Decision in this very case is later cited for that proposition. See SiOnyx Preliminary Response citing "Hamamatsu, IPR2016-01143, Paper 7 at 17" in the parallel '591 IPR, PTACTS PDF. Under Abbott Labs. v. Sandoz, 566 F.3d 1282 (Fed. Cir. 2009), product-by-process limitations are not patentable weight in the validity analysis if the prior-art product has the same structure — so a squarely presented § 103 case against claims 7–10 would still be strong.

5. Motivation-to-combine synthesis (MPEP 2143 / KSR)

6. Counterarguments and how they fare

1. Teaching away. '495 claim 11 recites an "average height … greater than about one micrometer," which the patent owner could argue discourages submicron structures. This is weak: disclosure of a preferred range or a single numerical example does not "teach away" from other ranges (In re Fulton; In re Gurley — a reference must criticize, discredit, or discourage the modification). Her 1998's own datum — spikes "taper to about 1-µm diam at the tip" — already places submicron feature cross-sections within the disclosure.
2. Unexpected results / different mechanism. The '446 spec asserts the water-based structures arise from a "different formation mechanism." But the same spec concedes "the later stages can be similar" to SF₆ processing and explains the size difference by a continuous physical relation (melt lifetime → capillary wavelength). A difference in degree, explained by known physics, is generally obvious.
3. Secondary considerations / nexus. SiOnyx commercialized "black silicon" imagers and won a D. Mass. verdict, which could support nonobviousness — but the Board nonetheless found claims 1–6 and 11 unpatentable, indicating the objective-evidence record did not overcome the prima facie case on these claims.
4. Product-by-process (claims 7–10). The procedural shield that kept claims 7–10 alive in the IPR is a burden-of-proof artifact, not a substantive nonobviousness holding.

7. Bottom line

• Claim 1 is the crux, and it is composition-of-matter narrow but obviousness-weak: its only substantive difference over US 2003/0029495 A1 + Her et al. (1998) is the size of features whose size the prior art teaches is governed by result-effective, tunable variables (ambient/immersion medium, fluence, wavelength, pulse count) through a mechanism (capillary waves in molten silicon) the prior art expressly identified.
• Consistent with that analysis, the PTAB in IPR2016-01143 held claims 1–6 and 11 unpatentable (Nov. 16, 2017), using § 102(b) for claims 1, 2, 4–6, 11 and § 103(a) for claim 3 — and claim 3's § 103(a) disposition shows the obviousness route was squarely available.
• Claims 7–10 were not instituted and thus were not adjudicated unpatentable; they are the surviving (though now expired) claims, and their survival is best explained by the product-by-process burden rather than by any affirmative finding of nonobviousness.
• The patent expired June 14, 2025 (adjusted expiration), so all of this is now of historical, estoppel, and defensive-value significance only.

Explicit uncertainties: (i) the specific exhibit references (Ex. 1002 et seq.) underlying the Board's § 102(b) ground were not retrievable in this session, so the primary reference named in the IPR is inferred, not confirmed; (ii) whether CAFC No. 18-1423 is the appeal of the '446 FWD is unverified; (iii) the publication date of the Mazur-group "Femtosecond Laser-Induced Nanometer-Scale Rods on Silicon Surface" paper was not established, so I have not relied on it; (iv) the '446's effective filing/priority date (Sept. 24, 2004 vs. Aug. 4, 2005) affects the § 102(b) critical date and should be confirmed against the file history before any rejection is finalized.