An integrated circuit, or IC, is a complete electronic circuit, transistors, resistors, and the wiring between them, fabricated together on a single small piece of semiconductor material. Before the IC, each component was made separately and then soldered together by hand, which limited how complex and how small a circuit could be. By building everything at once on one chip, the integrated circuit made it possible to put first dozens, then thousands, then billions of components into a space smaller than a fingernail.
The first working demonstration came from Jack Kilby at Texas Instruments in 1958. His patent, US 3,138,743, “Miniaturized electronic circuits,” describes building a circuit from “a body of single-crystal semiconductor material containing a plurality of electrical circuit components.” Kilby’s device proved the central idea, that multiple components could share one piece of semiconductor, though his early version still relied on fine wires to connect the parts.
The complementary breakthrough came from Robert Noyce at Fairchild Semiconductor, who solved the manufacturing problem of connecting the components cleanly. His patent, US 2,981,877, “Semiconductor device-and-lead structure,” assigned to Fairchild, describes “leads in the form of vacuum-deposited or otherwise formed metal strips extending over and adherent to the insulating oxide layer for making electrical connections.” This planar approach, using an oxide layer with metal interconnects deposited on top, was the form that could actually be mass-produced.
Kilby and Noyce are jointly credited as inventors of the integrated circuit, and the two companies eventually cross-licensed their patents after years of litigation. Kilby received the 2000 Nobel Prize in Physics for the invention; Noyce, who died in 1990, had by then co-founded Intel with Gordon Moore. The planar process Noyce’s patent describes became the foundation of essentially all later chip manufacturing.
The integrated circuit is what makes Moore’s Law meaningful. Because components are made together on one chip, shrinking them lets you fit exponentially more onto the same area, and that is precisely the trend Moore described in 1965. From the IC came the microprocessor, memory chips, and the entire path to modern computing, all built on the idea of putting many components on a single piece of silicon.