You can freely build on The Invention of the Modern Field-Effect Transistor
This patent expired in 1980. Every claim — 1 independent, 0 dependent — is now unenforceable. Anyone can use, reproduce, manufacture, sell, or offer for sale this technology without a license.
Original assignee
Bell Telephone Laboratories Inc
Patent granted
1963
Expired
1980
Forward citations
37
What this patent covers
The patent describes a semiconductor device that uses an electric field to control the flow of current between two regions of the same conductivity type, separated by a region of the opposite type. By placing a dielectric (insulating) layer over the surface and applying a voltage, the device creates an electric field that modulates the conductivity of the channel between the two P-N junctions. This mechanism allows a small input voltage to act as a gate, effectively turning the flow of electrons on or off, which is the basic requirement for binary logic in digital circuits.
What is now free to use
All 1 claims of US 3102230 are in the public domain. Specifically:
Claim 1: IN COMBINATION, A SEMICONDUCTOR WAFER — 1 specific element
The 0 dependent claims add narrowing limitations and are also free.
What is NOT covered
Patent expiry frees this specific invention. Separately-patented improvements made after expiry may still be protected.
Does not cover bipolar junction transistors (BJTs) which rely on current injection rather than electric field control.
Does not cover vacuum tubes or other non-semiconductor switching technologies.
Does not cover specific manufacturing lithography techniques used to build these devices at scale.
Who is building on this today
Every major semiconductor manufacturer, including Intel, TSMC, Samsung, and NVIDIA, builds upon the foundational physics described in this patent. The basic MOSFET architecture remains the primary building block for virtually all modern logic gates.
Products built on expired version of this technology
Modern computer CPUs (Intel Core, AMD Ryzen)
Smartphone processors (Apple A-series, Qualcomm Snapdragon)
Computer memory chips (DRAM and Flash storage)
How to cite this patent in your documentation
Bell Telephone Laboratories Inc. US Patent 3102230. Electric field controlled semiconductor device. Granted 1963, expired 1980. Now in the public domain.
Note: This is a convenience citation. Consult a patent attorney for formal freedom-to-operate analysis.
PatentBrief is an educational resource and does not provide legal advice. Patent expiration information is derived from USPTO records and may not reflect continuation patents, divisional filings, or separately-patented improvements. For commercial use or production decisions, obtain a formal freedom-to-operate (FTO) opinion from a registered patent attorney.