A lucky accident
Around the 1950s, many labs were attempting to figure out how to manufacture transistors. Even more exciting was the idea that many electrical components, entire circuits could be put on one crystal. There were several methods attempted to solve the problems that occurred, until one day, in 1955, a lucky accident suddenly made everything much easier.
Here’s ‘a video about how integrated circuits work.
Here’s an article with more information about integrated circuits.
Here’s an article about the 1955 lucky accident.