Why are microelectronics important?
It is widely believed that the transistor was the most important invention of the twentieth century. The first image shows the device that Bardeen and Brattain developed in 1947 in the Bell Labs; for this discovery. They received the Nobel Prize in Physics in 1956, in association with Shockley, who in 1949 made the first junction transistor, the prototype of solid-state transistors.
In fact, the transistor itself would not have determined the revolutionary developments in electronics, information technology, and telecommunications that we have witnessed in the past sixty years. With the transistors, the first radios and some elementary computers were made. However, we had stood still at discrete solid-state devices, the individual transistors, almost nothing of what then happened, would have happened.
To determine the development of modern electronics was above all the invention of the integrated circuit; that is, it has been possible to make more transistors, more active components, on the same base of semiconductor material, typically silicon.
So what is an integrated circuit?
It is a complete electronic system or subsystem, made with a single manufacturing process, on the same substrate. The neatest regions are memory areas where data is stored, while the region that looks like the map of an American city, with roads that cross at right angles, contains logic.
It is a microcontroller, an integrated circuit that can perform logic and calculation functions independently and has non-volatile memories on board to manage application programs. It can be the control unit of an entire appliance (e.g., a domestic appliance or numerically controlled tool) or part of it (e.g., the ABS of a car). The extreme case is represented by smart cards, in which the entire system consists of a single chip. As anticipated in the introduction, microelectronics is an enabling and pervasive technology:
1. it is enabling because it has made and makes possible new applications that would otherwise be inconceivable (for example, PC, mobile phones, laptops, smartphones, tablets, robotics, electronics in the car, home automation, video games)
2. It is pervasive because it affects all industrial sectors and almost all applications.
These two attributes, which are crucial to understanding the importance of microelectronics, explain the evolution of the semiconductor industry.
As the name suggests, it is all about the microfabrication of small electronic components and designs. If the fluctuations linked to the cyclical variability typical of a component market are neglected, the turnover of microelectronics has grown at a constant rate of 15% per year for forty years. Since 2001 the growth rate has decreased, not only due to the slowdown in the global economy but also because the semiconductor turnover could not continue to grow indefinitely at a rate higher than the global electronics market; it represents a part.
The growth of the microelectronics market was supported by the continuous succession of several radical downstream innovations made possible by the evolution of microelectronics itself. Defense orders fueled the initial development, and then there was a period of large computers for public bodies and large companies. Then the office computer and personal computers arrived, then all the portable instruments, from the phone to digital cameras, MP3 players and digital organizers.
We are now in the convergence phase because the evolution of technology has allowed all these digital and multimedia functions, initially provided by individual specialized devices. They are to be implemented in the same device today: a smartphone or tablet supports all these functions. Each of the applications had its typical sigmoid development cycle and often saw a decline. But microelectronics continued to grow because it supported all subsequent market cycles of the various applications—for example, the mainframe succession computer-server -PC-laptop-tablet.
If the annual semiconductor market has reached dimensions of the order of 250 billion dollars, the entire electronics industry, powered by microelectronics, is worth four times as much, therefore a thousand billion dollars.
If we also consider the market of final products, such as the automobile, household appliances, electro-medical systems, industrial automation, and the whole area of services related to the network and telecommunications. We can say that the overall economic value of all that depends on microelectronics is about 5000 billion.
The evolution from micro to Nanoelectronics
The other peculiar characteristic of microelectronics, anticipated in the introduction, is the technological progress at an exponential rate maintained for over fifty years; an evolution, it was said, without comparison in the field of industrial technologies.
From the beginning, the technological development of integrated circuits has aimed to reduce the size of the elementary components, so as to be able to integrate more and more on a single chip and thus create increasingly complex and powerful systems.
Evolution over the years of the number of transistors contained in the processors
The growth law, the doubling of the number of components every year, was predicted in the mid-1960s by Gordon Moore, co-founder of Intel, and is often referred to as “Moore’s law.”
In reality, it is not a law; it is the forecast, based on the few data available at that time, of a trend which, unless corrected on the rate of growth, has been confirmed for over 40 years, up to the present day.
But it was not only the size of the single component and, consequently, the number of transistors per chip that followed exponential development in recent years. The reduction of the geometries has been translated in equal measure in the increase of the switching speed, therefore by the rise of the frequency, in the reduction of the dissipated power, and in the reduction of the cost of every single elementary component.
All these factors were equally decisive for the evolution of the applications. There would be no portable electronics if the consumption were not reduced to the point that the complex functions 30 years ago. It could only be performed by computers that occupied a room and consumed kilowatts of power are now carried out by a mobile phone, powered by a battery.
Similarly, mainframes performing less than a few hundred dollars' PC today cost tens of millions of dollars and were only accessible to large corporations. These are all factors necessary to make most modern electronics applications possible: the smartphone would not exist without integrated circuits!
Why is it important?
The highest integration density is achieved with memories because the memory cells are arranged in an orderly manner in a matrix organization. Today, the largest memory on the market is 128 gigabit of flash memory (single chip). So, taking into account that these are memories that store two bits per cell, the density of the matrix in this chip is over 50 billion transistors (cells) per cm 2. The increase in density, as mentioned, was made possible by the continuous reduction in the size of the elementary components.
The subsequent technological generations of the integrated circuit manufacturing processes are identified by the size of the minimum geometries they can achieve. In 1970 the dimensions were in the order of ten microns (μm, a millionth of a meter). Today they are in the order of ten nanometers (nm, one billionth of a meter); that is, they have fallen by three orders of magnitude in 40 years.
The threshold for defining the perimeter of nanotechnologies is normally identified in 100 nm; microelectronics exceeded this threshold at the beginning of the last decade and, at present, nanoelectronics is by far the most important of nanotechnologies.
The most advanced processors are now produced in 14nm technology, and 10nm technology processors will be introduced shortly; the most advanced NAND memories are produced in 15nm technology. At a prototype level, the possibility of making transistors with dimensions less than 10 nm has already been demonstrated; therefore, evolution is expected to continue for a few more generations.
The race for extreme miniaturization is not, however, the only development trend of microelectronics. Electronic systems need to interface with the real world and, to do this, they need sensors and actuators.
One of the most important technologies of the more than Moore strand is MEMS (micro-electro-mechanical systems). In addition to the known electrical properties, silicon also has excellent mechanical properties; microelectronics' technological infrastructure allows us to exploit these properties to create mechanical systems on a micrometric scale. It also allows us to integrate or directly interface these mechanical micro-systems with the control electronics.
Today, all mobile phones and tablets are equipped with inertial sensors that allow you to keep the image on the screen vertical when you rotate the device. It is due to inertial MEMS sensors that video game consoles allow the user to play simulating real movements. Micromechanical gyroscopes allow cell phones not to lose their location when walking inside buildings.
Another successful application of more than Moore technologies is imaging.
Even high-end cameras are now equipped with digital sensors made of silicon. The sensors of the cameras are arrays of transistors and capacitors, covered by layers of transparent dielectric materials, suitably worked, which act as color filters and lenses for each pixel.
Author: Vicki Lezama