Integrated circuit
An integrated circuit (IC), also known as a chip or microchip, is a structure of small dimensions of semiconductor material, usually silicon, of a few square millimeters of surface area (area), on which electronic circuits are fabricated, generally by photolithography, and which is protected within a plastic or ceramic encapsulation. The encapsulation has metallic conductors suitable for making connection between the integrated circuit and a printed circuit.
ICs were made possible by experimental discoveries showing that semiconductor devices could perform the functions of vacuum tubes, as well as scientific advances in semiconductor manufacturing in the mid-century XX. The integration of large numbers of small transistors within a small space was a breakthrough in hand-crafting circuits using discrete electronic components. The mass production capability of integrated circuits, as well as the reliability and approach to building a block diagram in circuits, ensured the rapid adoption of standardized integrated circuits instead of designs using discrete transistors.
ICs have two main advantages over discrete circuits: cost and performance. The low cost is due to the chips; since it has all its components printed in a photolithography unit instead of being built one transistor at a time. Furthermore, packaged ICs use much less material than discrete circuits. Performance is high as the IC components change quickly and consume little power (compared to their discrete counterparts) as a result of their small size and close proximity of all their components. As of 2012, the typical chip area range is from a few square millimeters to around 450 mm², with up to 9 million transistors per mm².
Integrated circuits are used in virtually all electronic equipment today, and have revolutionized the world of electronics. Computers, mobile phones, and other electronic devices that are an indispensable part of modern societies are made possible by the low cost of integrated circuits.
History
On April 15, 1949, German engineer Werner Jacobi (Siemens AG) files the first patent application for integrated circuits with semiconductor amplifier devices. Jacobi made a typical industrial application for his patent, which was not registered.
Later, circuit integration was conceptualized by radar scientist Geoffrey Dummer (1909-2002), who was working for the Royal Radar Establishment of the British Ministry of Defense, in the late 1940s and early 1940s. 1950s.
Newly employed by Texas Instruments, Jack S. Kilby registered his initial ideas for the integrated circuit in July 1958, successfully demonstrating the first working integrated example on September 12, 1958. In his patent application dated September 6, In February 1959, Kilby described his new device as "a body of semiconductor material... in which all the components of the electronic circuit are fully integrated." It was a germanium device that integrated six transistors on the same semiconductor base to form a phase rotation oscillator. The first customer for the new invention was the United States Air Force.
In the year 2000 Kilby was awarded the Nobel Prize in Physics for the enormous contribution of his invention to the development of technology.
Robert Noyce developed his own integrated circuit, which he patented about six months later. He also solved some practical problems that the Kilby circuit had, such as the interconnection of all the components; by simplifying the structure of the chip by adding metal in a final layer and removing some of the connections, the integrated circuit became more suitable for mass production. In addition to being one of the pioneers of the integrated circuit, Robert Noyce was also one of the co-founders of Intel Corporation, one of the largest manufacturers of integrated circuits in the world.
Integrated circuits are found in all modern electronic devices such as watches, cars, televisions, MP3 players, mobile phones, computers, medical equipment, etc.
The development of integrated circuits was made possible by experimental discoveries that showed that semiconductors, particularly transistors, can perform some of the functions of vacuum tubes.
The integration of large numbers of tiny transistors onto small chips was a huge advance over the manual assembly of vacuum tubes (valves) and the fabrication of electronic circuits using discrete components.
The mass production capacity of integrated circuits, their reliability, and the ease of adding complexity, led to their standardization, replacing entire circuits with designs that used discrete transistors, and furthermore, quickly making tubes or valves obsolescent. empty.
There are three most important advantages that integrated circuits have over electronic circuits built with discrete components: their lower cost; its greater energy efficiency and its reduced size. The low cost is due to the fact that the ICs are manufactured by being printed as a single piece by photolithography from a wafer, generally silicon, allowing the production in large quantities, with a very low defect rate. The high efficiency is due to the fact that, given the miniaturization of all its components, the energy consumption is considerably lower, under the same operating conditions, than a homologous electronic circuit made with discrete components. Finally, the most notable attribute is its reduced size in relation to discrete circuits; to illustrate this: an integrated circuit can contain anywhere from thousands to several million transistors in a few square millimeters.
The advances that made the integrated circuit possible were primarily developments in the manufacture of semiconductor devices in the mid-20th century XX and the experimental discoveries that showed that these devices could replace the functions of valves or vacuum tubes, which quickly became obsolete as they could not compete with the small size, moderate power consumption, minimal switching times, reliability, mass production capability, and versatility of ICs.
Among the most complex and advanced integrated circuits are microprocessors, which control everything from cell phones and microwave ovens to computers. Digital memory chips are another family of integrated circuits, of crucial importance for the modern information society. While the cost of designing and developing a complex IC is quite high, when spread across millions of production units, the individual IC cost is usually kept to a minimum. The efficiency of the ICs is high because the small size of the chips allows short connections that allow the use of low consumption logic (as is the case of CMOS), and with high switching speeds.
As the years go by, integrated circuits evolve: they are manufactured in smaller and smaller sizes, with better features and performance, their efficiency and effectiveness improve, and thus more elements are allowed to be packaged (integrated) on the same chip (see Moore's law). As the size is reduced, other qualities also improve (cost and power consumption decrease, while performance increases). Although these gains are ostensibly for the end user, there is fierce competition among manufacturers to use ever thinner geometries. This process, and what is expected for the coming years, is very well described by the International Technology Roadmap for Semiconductors.
Microprocessor crisis
The global lockdown resulting from the COVID-19 pandemic in 2020 has caused an unprecedented increase in the demand for microprocessors, which has collapsed the global industry. The price of microchips has risen with spikes of up to 30 percent in the last 12 months. Dozens of factories that depend on microprocessors have delayed their production or closed temporarily, including in Spain. This crisis threatens consumers and highlights the weaknesses of a technology that could have peaked. In addition, it represents a turning point for the West, which until now dominated the technological market in terms of microchip development.
The microchip industry faces another major obstacle: Moore's Law, which according to some specialists is beginning to fail. In 1965 Gordon Moore, co-founder of Intel, formulated the law that bears his name, according to which the number of transistors that a microchip can contain doubles every two years. This postulate has made it possible to develop increasingly powerful computers at a lower cost. However, since 2010 the pace of innovation has started to slow down. In 2015, Intel CEO Bryant Krzanich recognized that there was a discontinuity in miniaturizing components cost-effectively. To manufacture a state-of-the-art microchip requires a very expensive and complex technology, “extreme ultraviolet lithography”.
Popularity
Only half a century has passed since their development began and integrated circuits have become almost ubiquitous. Computers, mobile phones and other digital applications are now part of modern societies. Computer, communications, manufacturing, and transportation systems, including the Internet, all depend on the existence of integrated circuits. In fact, many scholars consider the digital revolution caused by integrated circuits to be one of the most significant events in human history.
Types
There are at least three types of integrated circuits:
- Monolithic circuits: are manufactured in a single monocristal, usually silicon, but also exist in germanium, arseniuro of galio, silicon-germanium, etc.
- Fine-layer hybrid circuits: they are very similar to monolithic circuits, but they also contain difficult components to manufacture with monolithic technology. Many A/D converters and D/A converters were manufactured in hybrid technology until progress in technology made it possible to produce precise resistance.
- Heavy-layer hybrid circuits: they are quite apart from the monolithic circuits. In fact they usually contain monolithic circuits without a capsule, transistors, diodes, etc., on a dielectric substrate, interconnected with driving tracks. The resistances are deposited by screen printing and are adjusted by laser cuts. All this is encapsulated, in plastic or metal capsules, depending on the dissipation of caloric energy required. In many cases, the capsule is not mouldedIt simply covers the circuit with an epoxy resin to protect it. In the market there are hybrid circuits for applications in radio frequency modules (RF), power supply, automotive power circuits, etc.
Integrated circuits (CI) of different sizes
Classification
Based on the level of integration —number of components— integrated circuits can be classified as:
- SSI (Small Scale Integration) small level: 10 to 100 transistors
- MSI (Medium Scale Integration) medium: 101 to 1000 transistors
- LSI (Large Scale Integration) large: 1001 to 10 000 transistors
- VLSI (Very Large Scale Integration) very large: 10 001 to 100 000 transistors
- ULSI (ULSI)Ultra Large Scale Integration) ultra large: 100 001 a 1 000 transistors
- GLSI (Giga Large Scale Integration) large giga: more than a million transistors
Regarding the integrated functions, the circuits are classified into two large groups:
- Analog integrated circuits.
- They can count from simple encapsulated transistors together, without union between them, to complete and functional circuits, such as amplifiers, oscillators or even full radio receivers.
- Digital integrated circuits.
- They can be from basic logical doors (AND, OR, NOT) to the most complicated microprocessors or microcontrollers.
Some are designed and manufactured to serve a specific function within a larger, more complex system.
In general, the manufacture of ICs is complex since they have a high integration of components in a very small space, so that they become microscopic. However, they allow great simplifications with respect to the old circuits, as well as a more efficient and faster assembly.
Limitations of Integrated Circuits
There are certain physical and economic limits to the development of integrated circuits. Basically, they are barriers that are moving away as technology improves, but they do not disappear. The main ones are:
Power dissipation
Electrical circuits dissipate power. When the number of components integrated in a given volume grows, the requirements regarding dissipation of this power also grow, heating up the substrate and degrading the performance of the device. In addition, in many cases it is a positive feedback system, so that the higher the temperature, the more current they conduct, a phenomenon that is usually called "thermal runaway" and, if it is not avoided, it can destroy the device. Audio amplifiers and voltage regulators are prone to this phenomenon, which is why they usually incorporate thermal protections.
The power circuits, obviously, are the ones that must dissipate the most energy. To do this, its capsule contains metal parts, in contact with the bottom of the chip, which serve as a thermal conduit to transfer heat from the chip to the heatsink or to the environment. The reduction in thermal resistivity of this conduit, as well as of the new silicone compound capsules, allow greater dissipation with smaller capsules.
Digital circuitry solves the problem by lowering the supply voltage and using low-power technologies such as CMOS. Even so, in circuits with more integration density and high speeds, dissipation is one of the biggest problems, and certain types of cryostats have been used experimentally. Precisely the high thermal resistivity of gallium arsenide is its Achilles heel to make digital circuits with it.
Parasitic capacitances and self-inductions
This effect refers mainly to the electrical connections between the chip, the capsule and the circuit where it is mounted, limiting its operating frequency. With smaller pills the capacity and the autoinduction of them are reduced. In digital bus driver circuits, clock generators, etc., it is important to maintain the impedance of the lines, and even more so in radio and microwave circuits.
Limits on components
The components available for integration have certain limitations, which differ from their discrete counterparts.
- Resistors. They are undesirable because they need a lot of surface. This is why only reduced values are used and MOS technologies are almost completely eliminated.
- Condensers. Only very small values are possible and at the cost of a lot of surface. As an example, in the μA741, the stabilization capacitor comes to occupy a quarter of the chip.
- Inducers. They are commonly used in radio frequency circuits, being hybrids many times. In general they are not integrated.
Integration density
During the manufacturing process of integrated circuits, defects accumulate, so that a number of components of the final circuit do not work correctly. When the chip integrates a larger number of components, these defective components decrease the proportion of functional chips. That is why in memory circuits, for example, where there are millions of transistors, more than necessary are manufactured, so that the final interconnection can be varied to obtain the specified organization.
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