Invalidity dossier
US 5789800
Bipolar transistor having an improved epitaxial base region
Current assignee: Adeia Semiconductor Advanced Technologies Inc
Added 9/23/2026, 2:37:36 PM
Active provider: DeepSeek · deepseek-flash
Patent summary
Title, assignee, inventors, filing/issue dates, abstract, and a plain-language overview of the claims.
Patent Overview: US5789800A
Title: Bipolar transistor having an improved epitaxial base region
Patent number: US5789800A
Application number: US08/785,611 (filed 1997-01-17)
Priority date: 1996-01-17
Publication/grant date: 1998-08-04
Inventor: Hiroshi Kohno
Original assignee: NEC Corp. (Current assignee listed as Adeia Semiconductor Advanced Technologies Inc.)
Legal status: Expired – Lifetime (anticipated expiration 2017-01-17)
Purpose
The invention relates to a semiconductor device and its fabrication, and more particularly to a bipolar transistor having an improved epitaxial base region and a method of fabricating the same. The background notes that a molecular beam epitaxy system is useful for forming a shallow emitter junction—reducing emitter junction capacitance and emitter resistance—and that a self-alignment technique is useful for scaling the bipolar transistor down.
Plain-language scope
The disclosed fabrication begins with an n⁺-type silicon substrate. An n⁻-type silicon epitaxial layer is formed on it to create a wafer, and field oxide films are selectively formed by spot local oxidation. The claims and full text are not reproduced in the supplied excerpt. Prior-art keywords listed are: type, base, bipolar transistor, film, base region.
Source: https://patents.google.com/patent/[US5789800](/patent/US5789800)/en
What the excerpt does not establish
- Any claim language, claim count, or the specific claim limitations defining the protected scope.
- The complete detailed description (excerpt noted as omitted) or the full fabrication sequence beyond the initial spot local oxidation step.
- The figures and their reference numerals.
- Whether the listed "Current Assignee" reflects the operative owner; the source itself states assignees "may be inaccurate" and that legal-status statements are assumptions, not legal conclusions.
- An abstract, field-of-classification rationale, or cited prior-art references (none were supplied).
This overview is limited strictly to the supplied text.
Generated 10/1/2026, 9:52:07 PM
Cases on file (0)
Specific litigation cases in our database that name US patent 5789800. The free-form analysis below may also discuss cases beyond this list.
No cases on file mention this patent. Upload a CSV or add a case manually in Admin → Manage litigation cases.
Litigation summary
Past and pending lawsuits — plaintiffs, defendants, jurisdictions, outcomes, and notable rulings.
Proceedings on file (0)
All PTAB activity →AIA trial proceedings (IPR / PGR / CBM) filed at the USPTO Patent Trial and Appeal Board against this patent. Sourced from the USPTO Open Data Portal and refreshed every six hours; each proceeding number deep-links to the PTAB E2E docket.
No PTAB proceedings on file. This patent has not been challenged via IPR, PGR, or CBM. The absence is itself a signal — well-asserted patents eventually attract IPRs. The LLM analysis below may surface filings the ODP feed hasn’t indexed yet.
PTAB challenges
AIA trial proceedings at the USPTO Patent Trial and Appeal Board — IPR, PGR, and CBM. Petitioners, judge panels, claim-level invalidation outcomes from Final Written Decisions, and Federal Circuit appeals. The single most important defensive datapoint after litigation history.
Assignment history
Inventors, original assignee, and the chain of ownership recorded with the USPTO — including the correspondent attorney who recorded each assignment, since shell-LLC chains often share one repeat-player attorney even when the entity names look unrelated. Surfaces NPE / patent-troll patterns: shell-entity transfers, known asserters in the chain, repeat correspondent fingerprints, pre-litigation assignments, and bankruptcy fire-sales.
Prior art
Earlier patents, publications, and products that may anticipate or render the claims unpatentable.
Obviousness
Combinations of prior art that suggest the claimed invention would have been obvious under 35 U.S.C. § 103.
Extensions
Patent term adjustments, term extensions, continuations, divisionals, family members, and expiration dates.
Derivative works
Defensive disclosure: derivative variations of each claim designed to render future incremental improvements obvious or non-novel.