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How Integrated Circuits Got Invented

Written By: 

Mohit Parikh

If you pluck out a hair from your head and split it into two, the area of cross section you will see - or perhaps you will not see because it is so minuscule - that area can house thousands of electronic transistors that can connect intelligently to build a complex circuit. This scale of manufacturing is so sensitive that even a particle of dust or a microscopic entity like bacteria can corrupt the entire circuitry. Truly incredible are advancements in the science and the craft of circuit integration, but they are also a daily affair for hundreds of semiconductor companies across the world where hundreds of thousands of engineers labor and brainstorm.

Image Of Past Computer

Fig. 1: Image Of Past Computer

What is an everyday affair now was only a theoretical possibility half a century ago. Remember, there was a time when computers were the size of a large room. The more complex a computer was, the more the space it required to house its vacuum tube circuitry and the lower became the circuit’s reliability. These were the everyday unsolvable problems for the electronics industry. How we departed from the complex maze of the thick, heavy vacuum tubes and arrived at today’s nano-scale integration is the journey that hinges on a single, defining invention: the invention of Integrated Circuits; and guided by a single, ages old adage: necessity is the mother of invention.  

What necessitates this invention is the infamous ‘tyranny of numbers’ problem.

The Tyranny of Numbers

Already in the early 1950s, Bells lab had developed small and reliable transistors. It was thought that if the size of electronic components is reduced, all the volume related problems would be solved and it would be painless to create complex circuitry. There were, however, unanticipated problems accompanying miniaturization.

A circuit is not just about its components, it is also about its connections. And for any circuit to work the connections must be stable – it is through them the electrons (the currents) flow from one component to another. Connections are the channel of interaction. And an error prone channel would make the whole circuit defunct.

Back then, the circuits were made by hands – laborers soldered the different components to vacuum tubes with metal wires. When the size of components got down, it became evident that assembling the tiny semiconductor components manually would lead to faulty connections. The errors were unavoidable and there was no way to maintain a quality check.

In1958 TI had a new employee who had not yet earned his vacation time. Jack Kilby was supposed to be working. So, to make the most of his time, he dived headlong into the core problem of the day and came up with a briliiant solution.

The second problem was the size. A complex circuit relied on speed. If the metal wires were too long, the electric signals wouldn't move fast enough. This would make the circuits inefficient.

These two problems, together, were the problems of numbers; infamously called The Tyranny of Numbers. In a nutshell, the problem stated that any advanced circuit would have so many parts and connections that it was not practical to make it.

The Prophecy of a Solution: No Connecting Wires

British radio engineer Geoffrey Dummer had addressed these problems optimistically back in 1942. He had said, “With the advent of the transistor and the work in semiconductors generally, it seems now to be possible to envisage electronic equipment in a solid block with no connecting wires. The block may consist of layers of insulating, conducting, rectifying and amplifying materials, the electrical functions being connected by cutting out areas of the various layer.”

He was ‘the prophet of integrated circuits’- the one who could see their coming in the near future. He had prophesied a theoretical solution to the obvious problem: connection free circuits. But it was in the hands of two engineers, working separately in different labs at the same time in the same country that the prophecy began to take physical shape.

Jack Kilby's Masterpiece - The Monolithic IC

In the summer of 1958, Texas Instruments shut down for a company-wide two week vacation. This was something they did every year. In 1958 though they had a new employee who had not yet earned his vacation time. Jack Kilby was supposed to be working. So, to make the most of his time, he dived headlong into the core problem of the day and began searching for a substitute to the in-practise miniaturization methods for circuits. Due to his previous experience at Centralab in Milwaukee, Kilby was familiar with the "tyranny of numbers" problem. He realized that the only commodity a company could manufacture cheaply was a semiconductor. So, he concluded, all circuit components should be made from the same material from which the semiconductors are made. Nobody had thought that before.

 Image Of The World's First Integrated Circuit (IC)

Fig. 2: Image of The World's First Integrated Circuit (IC)

Kilby drew up a few sketches for this process. When the vacation ended, he showed those sketched to his manager Willis Adcock. Adcock found them to be brilliant but he was unsure about them. He asked Kilby to go ahead anyway and build a working circuit of silicon. This proved to be a significant management decision as on August 28, 1958, Kilby showed a successfully working circuit to Adcock and immediately received a green flag for his project. In his next circuit, he integrated all the electronic and electrical components on a single bar of germanium.  

That device was put to test and it worked just as Kilby had predicted. Thus, he had solved one of the most perplexing problems associated with miniaturization. Once his invention was accepted by the people in the industry, it was all set to revolutionize electronics technology.

"The thought led me to the conclusion that semiconductors were all that were really required — that resistors and capacitors [passive devices], in particular, could be made from the same material as the active devices [transistors]. I also realized that, since all of the components could be made of a single material, they could also be made in situ interconnected to form a complete circuit," Kilby recalled in an article titled ‘Invention of the IC’ in 1976.

He added, “What we didn't realize then was that the integrated circuit would reduce the cost of electronic functions by a factor of a million to one. Nothing had ever done that for anything before.”

The Three Problems of Microelectronics

Connections, by the way, weren’t the only area of concern. There were, in fact, three distinct and fundamental issues to miniaturization of electronic components. In 1958, Torrek Wallmark described them as:

1.     Problem of Integration: In 1958, the various electronic components could not be integrated into one semiconductor crystal because alloying was not fit for IC. How do you integrate them?

2.     Problem of Isolation: At the atomic level, how do you ensure that the different components are not overlapping each other? How do you keep them isolated, electrically, on one semiconductor crystal?

3.     Problem of Connection: How do you connect the microelectronic components reliably? The only available method back then was the extremely expensive and time-consuming one using gold wires.

"If the auto industry advanced as rapidly as the semiconductor industry, a Rolls Royce would get a half a million miles per gallon, and it would be cheaper to throw it away than to park it."

The solutions were soon found. Three corporations invented them separately and held the key patents to each of the three problems. While Sprague Electric Company decided not to develop ICs, Texas Instruments, where Kilby worked, seemed to constrain itself. Fairchild Semiconductor however combined the different techniques needed for commercial fabrication of monolithic ICs and went ahead. At Fairchild, resided another genius mind without whose pioneering efforts ICs would have remained a theoretical concept, a possibility, for a long time. The genius was the co-founder of Fairchild who would go on to co-found the electronics giant Intel.

Robert Noyce’s Pioneering Efforts

Robert Noyce, individually, and only six months after Kilby, came up with his idea for the integrated circuit at Fairchild. Noyce had cracked many practical problems that were there in Kilby's circuit, specially the problem of interconnecting the components. He had added metal as a final layer and then removed part of it so that the wires were formed.  By getting rid of the "flying-wire" connections, Noyce introduced a practical method of mass manufacturing Jack Kilby's solid circuits.

In July 1959 Noyce filed his "Semiconductor device-and-lead structure" patent and then a group of expert Fairchild engineers made the first working monolithic ICs in May 1960.

Thus began improvements that made IC apt for commercial production.

Early Success of the Micro Chip

Like in all cutting edge technologies, the integrated circuit first found a taker in the military. As early as 1961, the first computer using silicon chips was manufactured for the Air Force and applied in the Minuteman Missile in 1962. Since there was a need for a product that could make everybody see the importance of IC technology (and help make it popular), Kilby designed a calculator which was as powerful as the huge electro-mechanical desktop calculator of the day, and yet small enough to handle on a palm. This reduction in size led to a huge success of his calculator – one of the first commercial applications of the IC technology – and opened pathways for the integration technology in the manufacturing space.

Patents for the Integrated Circuit

Both Kilby and Noyce are regarded as inventors of IC. If one of them came up with a revolutionary new idea for integration, the other made sure the practical problems associated with them do not come in the way of the idea to reach its potential. But things weren’t exactly seamless in the two companies these genius engineers worked for. Fairchild and TI files for patents in 1959. Jack Kilby and Texas Instruments received U.S. patent #3,138,743 for miniaturized electronic circuits and Robert Noyce and the Fairchild Semiconductor Corporation received U.S. patent #2,981,877 for a silicon based integrated circuit. This was followed by litigations over the patents for a decade.

Before things could get ugly, the two parties settled on a commercial solution. And the two inventors got their due. Kilby and Noyce were awarded the National Medal of Science in 1979. Noyce very humbly said, “There is no doubt in my mind that if that invention had not arisen at Fairchild that it would have arisen elsewhere in the very near future. It was an idea whose time had come and the technology had developed to a point where it was viable.”

Image Of Fairchild Semiconductor Type F Flip Flop

Fig. 3: Image Of Fairchild Semiconductor Type F Flip Flop

The Evolution of the Integrated Circuit

We have come a long way since Jack Kilby developed the first prototype of IC. The transistors on chips are now around 90 nm: to give another measure of the achievement, in a single red blood cell one can insert hundreds of these transistors. Gordon Moore, one of the early integrated circuit pioneers and founders of Intel once said, "If the auto industry advanced as rapidly as the semiconductor industry, a Rolls Royce would get a half a million miles per gallon, and it would be cheaper to throw it away than to park it." This rapid growth in miniaturization techniques was made possible by the vision of the first prototype of Kilby, and of the shrewd practical improvements of Noyce.

Recognizing the same, the Nobel committee awarded Jack Kilby the Nobel Prize for Physics in the year 2000 – the highest honor any human being can receive. Robert Noyce had passed away by then so he couldn’t share the award. His contributions though have never been disputed. The credit for the invention of IC is given to the two engineers jointly.

Thanks to the exponential development in semiconductor technology, we are advancing rapidly as a civilization. Every six months our computers are becoming more powerful and cheaper, and hundreds of innovations are happening every day in the computing space. The invention of IC, without a shred of doubt, has changed the course of human history, for IC lies at the heart of every modern electronic product on earth.