Definition
A field-effect transistor that uses the electric field from an insulated gate to control conduction in a semiconductor channel, serving as the basic switching device in MOS integrated circuits.
What it is
A MOSFET places an insulating oxide layer between a metal or polysilicon gate and the semiconductor, using the gate's electric field to control whether the channel conducts. It is a voltage-controlled device that can act as a switch in digital logic.
Why it emerged and what problems it solved
The input current, power consumption, and density of bipolar transistor logic limited larger-scale integration. The MOSFET's insulated gate reduced the input drive requirements, while its planar structure suited repeated fabrication through photolithography.
Why it matters and what it enabled
MOSFETs allowed logic, memory, and processors to share the same type of high-density device. Silicon-gate processes, MOS ICs, and CMOS subsequently addressed different trade-offs among speed, yield, and power consumption, ultimately providing the devices for microprocessors.
Principles and impact
Problems solved
- Controls switching with very little gate current, reducing the static drive burden of large-scale logic.
- Provides a device structure suited to planar fabrication and high-density integration.
Principles
- The oxide layer between the metal or polysilicon gate and the semiconductor forms a capacitor.
- The gate's electric field changes the surface carrier concentration, forming or shutting off a conducting channel.
Improvements
- Insulation between gate and channel keeps input current low and facilitates large arrays.
- Device dimensions can shrink with photolithography, enabling greater logic and memory density.
Significance
- Became the core device of MOS ICs, CMOS, DRAM, and microprocessors.
- Combines lower power consumption per function with higher chip density.
History and applications
People
John Atalla、Dawon Kahng
Organizations
Bell Telephone Laboratories
Events
Atalla and Kahng fabricated a MOS structure in 1959、A working MOS field-effect transistor was demonstrated in 1960
Applications
MOS logic gates、Semiconductor RAM and ROM、Microprocessor logic
Limitations
- Oxide defects, contamination, and interface states can cause stability and reliability problems.
- As devices shrink, short-channel effects, leakage, and heat dissipation become new constraints.
Upstream and downstream relations
Upstream
Sources: The Silicon Engine Timeline1964: First Commercial MOS IC Introduced
Downstream
Sources: 1963: Complementary MOS Circuit Configuration is Invented
Sources: 1964: First Commercial MOS IC Introduced1970: MOS Dynamic RAM Competes with Magnetic Core Memory on Price