The first computers took up the space of entire buildings, and their computing power was millions of times lower than that of today's cheap and small devices. This state of affairs was the result not only of the low efficiency of the components at that time, but also of the fact that one large element could handle only one task. The most important step towards miniaturization of electronic devices was the invention of the integrated circuit.
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The First Integrated Circuit. What Applications Did the Oldest Circuits Have?
The first attempt to create an integrated circuit was made in the late 1940s by Geoffrey Dummer. Although he managed to create the theoretical foundations for such solutions, he did not create the circuit itself. However, projects carried out independently by two researchers under the aegis of two different companies – Jack Kilbie of Texas Instruments and Robert Noyce of Fairchild Semiconductor – were successful.
The first to be presented – in 1958 – was a circuit created by Kilby, and he is considered the creator of this invention (42 years later he was awarded the Nobel Prize for this). Its housing contained several transistors and other elements, thanks to which it could perform tasks previously distributed to many components, and the power supply was common to all. At first, integrated circuits were produced with a strictly defined purpose. Devices from that time worked, among others, as flip-flops, amplifiers or computing systems (SSI – Small Scale Integration). With the development of this technology, integrated circuits could also be used as more complex components – decoders, counters or registers (MSI – Medium Scale Integration).
Microprocessors and digital integrated circuits
Another breakthrough that allowed modern electronics to develop and achieve current capabilities was the creation of the microprocessor. The person responsible for its development was Marcian "Ted" Hoff - an engineer at Intel. Intel 4004, as the hardware debuted, integrated the entire processor in a single integrated circuit. Although by today's standards it was a primitive system, it became the beginning of a new era in the history of computing. It was equipped with 2,300 transistors and operated on a 4-bit machine word. The clock frequency was only 740 kHz.
The next step was to create the Intel 8080 microprocessor. This 8-bit processor appeared on the market in the 1970s and found many practical applications. Progress quickly gained an exponential pace. Gordon Moore, one of the founders of Intel, predicted in 1965 that the number of transistors in integrated circuits would double every 18 months. His prediction, now known as Moore's Law, is still accurate, although in recent years this pace has slowed to 24 months. Today, electrical engineering has the technologies to make circuits consisting of billions of transistors, and their capabilities are constantly growing.
How is an integrated circuit constructed?
What exactly is a microprocessor and how is it built? It consists of several layers of semiconductor, dielectric and metallic materials. The basis of the entire structure is a thin, flat piece of silicon, a wafer, on which subsequent layers are applied. Silicon is an important material for the production of integrated circuits because of its unique semiconductor properties and the ability to operate in a wide temperature range.
The silicon wafer contains transistors, which are the basic element of the integrated circuit. These are miniature switches that allow you to control the flow of electric current. In modern processors, there can be even tens of billions of them.
The production process of integrated circuits is based on photolithography. After preparing a silicon wafer, a thin layer of photosensitive material is applied to it. Then, using ultraviolet light and a special template, a specific part of the wafer is exposed, according to a previously designed connection pattern. The exposed areas of the material are hardened, and the remaining ones are chemically removed. The exposed parts of the wafer are then etched, which allows for the creation of appropriate structures in the semiconductor.
The next step is to place layers of various conductive and insulating materials. Each layer has its own specific functions – it creates conductive paths, isolates elements from each other or creates transistor structures. The most commonly used material for creating conductive paths is copper, which perfectly conducts electricity. In the process of building integrated circuits, it is very important that each layer is precisely applied and perfectly matched to the other layers, which requires great precision.
Inside the integrated circuit, transistors are connected to each other by metal paths that conduct electrical signals. These must be carefully planned and made – the efficiency and reliability of the entire system depend on this. Modern processors have billions of connections, which greatly complicates their construction. Metal paths are applied in the photolithography process, similarly to other elements of the system. Each layer of paths is isolated from the previous one using dielectric materials, which prevents short circuits.
Basic types of integrated circuits
Due to the type of signals processed, there are two types of digital systems. The first is digital integrated circuits, which are the most common type of integrated circuits, working with binary signals (with values 0 and 1). They are used in logical and arithmetic operations. Systems of this type are the basis of computer processors and many other control systems - they are commonly used by IT infrastructure .
The second type is analog integrated circuits designed for continuous analog signals. These signals can take on any values within a specified range. Analog circuits are often used in communication and audio systems. Their main types are operational amplifiers, oscillators, analog-to-digital converters (ADC) and digital-to-analog converters (DAC), and memory chips.
Principle of operation of integrated circuits
Integrated circuits are the foundation of all modern electronic devices. This technology has made it possible to miniaturize equipment and increase its efficiency many times over. The variety of their types and the ability of individual types to process both digital and analog signals means that computers and controllers produced today are able to perform complex tasks. Their capabilities – thanks to the increasing number of transistors – are growing year by year, which allows us to implement projects that were the domain of science fiction a few decades ago. The future of the industry will certainly bring even greater innovations – and this in the coming years.