What is an Integrated Circuit?

An integrated circuit, also known as a microchip or IC, is a device made up of miniature active and passive electronic components like transistors and resistors. These are patterned on a single substrate of semiconductor material, typically silicon.

The earliest concept of an IC dates back to 1949, when German engineer Werner Jacobi lined up five transistors in a three-stage amplifier arrangement.

The IC’s Origins

The invention of the integrated circuit, or IC, was a major milestone in computer science. Its ability to reduce the amount of space needed for the movement of electricity through computer components greatly increased the efficiency and power of modern computers. Without the IC, laptops might not have the slim designs they have today, cars might not have many of their bells and whistles, and smartphones might not be the size of a thumb.

Engineers working for the Texas Instruments (TI) company began experimenting with the idea of placing all programmable voltage reference of a computer’s electrical parts on a single chip. These specialized components included transistors, resistors, diodes, and capacitors.

Using the transistors developed by William Shockley and his team at the AT&T Corporation’s Bell Laboratories in 1947, the TI engineers were able to create a device that could perform electrical functions such as signal amplification that had previously been done by vacuum tubes.

One of Kilby’s colleagues at TI, Robert Noyce, independently invented the first monolithic integrated circuit. Noyce had been working on the idea for about a year, but was unaware of Kilby’s work.

Noyce also patented the planar integrated circuit. This technology used transistors arranged in two parallel pairs, with a groove running through the middle. The pair of transistors were connected by wires that were patterned with photolithography.

The IC’s Development

Integrated circuits contain thousands to millions of electronic components like resistors, diodes, transistors, and capacitors that interconnect to perform a specific function. One IC can have several different functions, including audio amplification or voltage regulation. ICs are the foundation of every computer, mobile phone, airplane, subway train, car, and toothbrush that we use today.

Prior to the invention of ICs, circuits were constructed by placing groups of wires and transistors on a board. This process was very time consuming because many different parts had to be fabricated separately and then soldered together. It also limited the size of the device because there were only so many parts that could fit on a piece of circuit board.

Geoffrey Dummer, an electronics engineer from England, is credited with being the first person to conceive of a circuit that could be manufactured on a single chip. However, it was not until 1959 that his vision became reality.

The IC development started with a fundamental problem: how to reduce the size of critical computing components of varying types. It was important that these components be small because they were needed to provide the necessary functionality for many different applications.

During this phase, the high-level functional description of the desired IC is decomposed into the required low-level circuit elements. These are then assembled and interconnected using a logic or circuit design software. The resulting collection of ideal diode devices is then simulated to verify the functionality of the IC.

The IC’s First Inventors

A few years after the invention of transistors, engineers wanted to create electronic equipment that was even smaller. Vacuum tubes were already far too large, but transistors were too expensive to be affordable.

In order to make small, inexpensive electronics, manufacturers needed to find a way to combine circuit components on one piece of semiconductor material. It would also be helpful if the individual transistors could be made more reliable by laying small paths of metal directly on the semiconductor that acted as wires.

At the same time, two different individuals – Jack Kilby of Texas Instruments and Robert Noyce of Fairchild Semiconductor Corporation – independently came up with the idea for the integrated circuit. Both had backgrounds working on radar technology.

Kilby came up with the idea for the IC after he noticed that the manufacturing process used to make individual transistors and diodes left behind a thin film of silicon oxide that made them conductive. He thought that this layer could be used to make a whole circuit and he began experimenting with it.

Noyce was at Fairchild Semiconductor and had worked on a similar project. He was also influenced by work done by Kurt Lehovec of Sprague Electric Co., who had patented the concept of p-n junction isolation, which is used in every IC today.

The IC’s First Patent

With the transistor becoming a reality, engineers began to wonder if it was possible to put several electronic components on a single piece of semiconductor. This would be a major step forward because it could lead to significant improvements in performance and reliability as well as reductions in size.

Two separate inventors, Jack Kilby and Robert Noyce, independently developed the integrated circuit (also known as a microchip) at about the same time. Both worked on their inventions while at the Texas Instruments Semiconductor Corporation in Dallas, but had no knowledge of each other’s work.

In the late 1950s, Geoffrey Dummer from the Royal Radar Establishment in England presented a paper that discussed a new idea. The idea was to reduce the amount of space needed to move electricity through computer components. The typical computer of the day contained thousands of individual parts that were soldered together by hand. This approach was both expensive and fragile. Dummer predicted that a future technology would allow the parts to be manufactured as solid blocks without any wires.

Meanwhile, in 1959, at TI, Jack Kilby was blissfully unaware of Dummer’s ideas and, working alone, invented the first crude integrated circuit. Almost simultaneously, at Fairchild Semiconductor in North Adams, Massachusetts, engineer Kurt Lehovec was also developing a technique for alloying semiconductors from a liquid column into a silicon wafer using capillary alloying.