# The Invention of the Modern Field-Effect Transistor

> This 1960 patent describes the fundamental structure of the MOSFET, the tiny electronic switch that powers every modern computer processor.

- **Patent:** US 3102230
- **Original title:** Electric field controlled semiconductor device
- **Owner:** Bell Telephone Laboratories Inc
- **Granted:** 1963
- **Status:** Public domain (expired)
- **Times cited:** 37
- **Field:** semiconductors, consumer_electronics

## What it does

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 it does NOT cover

- 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.

## The clever bit

The innovation was using an insulating dielectric layer to isolate the control gate from the semiconductor, preventing current leakage into the gate while still allowing the electric field to influence the channel.

## Real-world examples

1. Modern computer CPUs (Intel Core, AMD Ryzen)
2. Smartphone processors (Apple A-series, Qualcomm Snapdragon)
3. Computer memory chips (DRAM and Flash storage)

## Why it matters

This is the foundational patent for the Metal-Oxide-Semiconductor Field-Effect Transistor (MOSFET). It is arguably the most important patent in the history of computing, as it enabled the miniaturization of transistors that allowed for the creation of integrated circuits and microprocessors.

## Frequently asked questions

### What does The Invention of the Modern Field-Effect Transistor cover?

This 1960 patent describes the fundamental structure of the MOSFET, the tiny electronic switch that powers every modern computer processor.

### Who owns patent US 3102230?

Bell Telephone Laboratories Inc owns this patent, granted in 1963.

### When does this patent expire?

This patent has expired and is now in the public domain — anyone can use the invention freely.

### What is patent US 3102230 cited by?

This patent has been cited by 37 later patents that build on its ideas.

### What problem does this patent solve?

This is the foundational patent for the Metal-Oxide-Semiconductor Field-Effect Transistor (MOSFET). It is arguably the most important patent in the history of computing, as it enabled the miniaturization of transistors that allowed for the creation of integrated circuits and microprocessors.

### What does this patent NOT cover?

Does not cover bipolar junction transistors (BJTs) which rely on current injection rather than electric field control.

**Full plain-English explainer:** https://patentbrief.org/patent/us/3102230/mosfet-field-effect-transistor

**Original patent:** https://patents.google.com/patent/US3102230

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_Source: PatentBrief — https://patentbrief.org. Patent facts are from public records; the plain-English explanation is PatentBrief's._


## Related patents

Semantically similar inventions in the PatentBrief corpus:

- [The Invention of the Junction Transistor](https://patentbrief.org/patent/us/2569347/junction-transistor) — William Shockley's 1951 patent for the junction transistor, the fundamental building block of all modern digital electronics.
- [The Invention of the Transistor](https://patentbrief.org/patent/us/2524035/point-contact-transistor) — Bell Labs' 1950 patent for the point-contact transistor, the fundamental electronic component that makes all modern computing possible.
- [How Robert Dennard Invented the One-Transistor DRAM Memory Cell](https://patentbrief.org/patent/us/3387286/dram-memory-dennard) — IBM's 1967 patent for a memory cell using a single transistor and a capacitor, which became the foundation for all modern computer RAM.
- [How Robert Noyce Invented the Modern Integrated Circuit](https://patentbrief.org/patent/us/2981877/noyce-planar-integrated-circuit) — Robert Noyce's 1959 patent for a semiconductor device that uses evaporated metal leads to connect components directly on a single silicon chip.
- [How Flash Memory Cells Use an Erase Gate to Clear Data](https://patentbrief.org/patent/us/4531203/nand-flash-memory) — This 1985 patent describes the foundational structure of flash memory, introducing an 'erase gate' that allows data to be electrically wiped from a memory cell.