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Knowledge Center

Integrated Circuits (ICs)

Integration of multiple devices onto a single piece of semiconductor


The integrated circuit is the building block of almost all technology today. It is a small square or rectangle of semiconductor material, often silicon, that contains electronic circuits laid down or grown to do computation or other tasks. The concept was to embed a number of transistors and other devices onto a single piece of silicon and to form the interconnections within the silicon itself. Before the integrated circuit, electronic components, such as transistors, resistors, diodes, inductors, and capacitors, were manually wired together on a board. The integrated circuit allowed for more powerful, lightweight, miniaturized applications by integrating components onto one chip of material.

In 1959 Jack Kilby of Texas Instruments received U.S. patent #3,138,743 for miniaturized electronic circuits and Robert Noyce of Fairchild Semiconductor received U.S. patent #2,981,877 for a silicon based integrated circuit. After several years of legal battles (up until 1966), the two companies decided to cross license each others patent and the IC industry was born.

The three main types of integrated circuits are analog, digital, and mixed signal circuits. Integrated circuits may be monolithic — one piece of silicon, where components are added in one layer, or they may be more complex, such as chiplets that have more than one piece of silicon.

The digital integrated circuit consists of transistors, contacts, and interconnects. To be sure, though, there is an inflection point taking place in leading-edge chips. The transistor resides on the bottom of the structure and serves as a switch. The interconnects, which reside on the top of the transistor, consist of tiny copper wiring schemes that transfer electrical signals from one transistor to another. The transistor structure and interconnects are connected by a layer called the middle-of-line (MOL). The MOL layer consists of a series of tiny contact structures.

Fig. 1: Interconnect, contact and transistor at various nodes. Source: Applied Materials.

The IC design flows for digital, analog, and mixed signal chips differ in how they deal with the two main design steps:

  • functional design and verification
  • physical design and verification

The IC manufacturing process consists of front-end-of-the-line (FEOL) is where the transistors are created, sometimes a middle-of-the-line (MOL) step where contacts are created, and backend-of-the-line (BEOL) where the interconnects are made. Test and packaging are next steps in the process.



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