An integrated circuit (IC), sometimes called a chip, microchip or microelectronic circuit, is a semiconductor wafer on which thousands or millions of tiny resistors, capacitors, diodes and transistors are fabricated. An IC can function as an amplifier, oscillator, timer, counter, logic gate, computer memory, microcontroller or microprocessor.
An IC is the fundamental building block of all modern electronic devices. As the name suggests, it's an integrated system of multiple miniaturized and interconnected components embedded into a thin substrate of semiconductor material (usually silicon crystal).
Microcontrollers are integrated circuits that govern specific operations in embedded systems, consisting of a processor, memory and input/output peripherals on a chip. This image shows a Microchip Technology ATtiny817 microcontroller.
A single IC could contain thousands or millions of:
● transistors
● resistors
● capacitors
● diodes
Additional components may also reside on it, all interconnected through a complex web of semiconductor wafers, silicon, copper and other materials. Size-wise, each component is small, usually microscopic. The resulting circuit, a monolithic chip, is also tiny -- often just enough to occupy a few square millimeters or centimeters of space.
One common example of a modern-day IC is the computer processor, which typically contains millions or billions of transistors, capacitors, logic gates, etc., connected together to form a complex digital circuit. Although the processor is an IC, not all ICs are processors.
History and evolution of integrated circuits
The invention of the transistor -- a combination of the words transfer and resistor -- in 1947 set the stage for the modern computer age.
In the early days, each transistor came in a separate plastic package, and each circuit consisted of discrete transistors, capacitors and resistors. Due to the large size of these components, early ICs were only capable of holding a few of them -- wired together -- on the circuit board.
Over time, the development of solid-state electronics made it easier to reduce the size of components.
In the late 1950s, inventors Jack Kilby of Texas Instruments, Inc., and Robert Noyce of Fairchild Semiconductor Corporation found ways to lay thin paths of metal on devices and have them function as wires. Their solution to the problem of wiring between small electrical devices was the beginning of the development of the modern IC.
Integrated circuits have undergone several generations of advancements according to their design assembly, size and number of components per chip.
Modern integrated circuits: Design and construction
For the past half-century, ICs have progressed enormously with faster speeds, greater capacity and smaller sizes.
Compared to the early days, today's ICs are unbelievably complex, capable of holding billions of transistors and other components on a single small piece of material. The modern IC is all one piece, with individual components embedded directly into the silicon crystal, rather than simply mounted on it.
An IC relies on multiple levels of abstraction. The semiconductor wafer that makes up the IC is fragile and contains numerous intricate connections between its many layers. A combination of these wafers is known as a die.
With millions or billions of components on one single chip, it's not possible to position and connect each component individually. Dies are too small to solder and connect to. Instead, designers use a special-purpose programming language to create small circuit elements and combine them to progressively increase the size and density of components on the chip to meet application requirements.
