ELECTRONICS AND MICROELECTRONICS

I. The intensive effort¹ of electronics to increase the reliabil­ity² and performance³ of its products while reducing their size and cost has led to the results that hardly anyone would have dared to predict.⁴

The evolution of electronic technology is sometimes called a revolution. What we have seen has been a steady quantitative evolution: smaller and smaller electronic components performing increasingly complex electronic functions at ever higher speeds. And yet there has been a true revolution: a quantitative change in technology has given rise to qualitative change in human capabil­ities.⁵

It all began with the development of the transistor.

Prior to⁶ the invention of the transistor in 1947 its function in an electronic circuit could be performed only by a vacuum tube. Tubes came in so many shapes and sizes and performed so many functions that in 1947 it seemed audacious (слишком смело) to think that the transistor would be able to compete⁷ except in limited applications.

The first transistors had no striking advantage in size over the smallest tubes and they were more costly. The one great advan­tage the transistor had over the best vacuum tubes was exceed­ingly⁸ low power consumption. Besides they promised greater reliability and longer life. However it took years to demonstrate other transistor advantages.

With the invention of the transistor all essential circuit func­tions could be carried out⁹ inside solid¹⁰ bodies. The goal¹¹ of creating electronic circuits with entirely solid-state components had finally been realized.¹²

Early transistors, which were often described as being a size of a pea (горошина), were actually enormous on the scale¹³ at which electronic events¹⁴ take place, and therefore they were very slow. They could respond¹⁵ at a rate¹⁶ of a few million times a second; this was fast enough to serve in radio and hearing-aid (слуховой аппарат) circuits but far below the speed needed for high-speed computers or for microwave communication systems.

It was, in fact, the effort to reduce the size of transistors so that they could operate at higher speed that gave rise to the whole technology of microelectronics.

A microelectronic technology has shrunk¹⁷ transistors and other circuit elements to dimensions¹⁸ almost invisible to unaided eye (невооруженный глаз).

The point¹⁹ of this extraordinary miniaturization is not so much to make circuits small per se (лат. сами по себе) as to make circuits that are rugged (зд. массивный), long-lasting, low in cost and capable of performing electronic functions at ex­tremely high speeds. It is known that the speed of response de­pends primarily on the size of transistor: the smaller the transistor, the faster it is.

The second performance benefit²⁰ resulting from microelec­tronics stems directly from the reduction of distances between cir­cuit components. If a circuit is to operate a few billion times a sec­ond the conductors that tie the circuit together must be measured in fractions of an inch. The microelectronics technology makes close coupling²¹ attainable.²²

It may be helpful if we say a few words about four of the prin­cipal devices found in electronic circuits: resistors, capacitors, diodes and transistors. Each device has a particular²³ role in con­trolling the flow of electrons so that the completed circuit per­forms some desired function.

During the past decade the performance of electronic systems increased manifold²⁴ by the use of ever larger numbers of compo­nents and they continue to evolve. Modern scientific and business computers, for example, contain 10⁹ elements; electronic switch­ing²⁵ systems contain more than a million components.

The tyrany of numbers - the problem of handling²⁶ many dis­crete electronic devices — began to concern²⁷ the scientists as early as 1950. The overall²⁸ reliability of the electronic system is universally related to the number of individual components.

A more serious shortcoming²⁹ was that it was once³⁰ the uni­versal practice to manufacture³¹ each of the components sepa­rately and then assemble³² the complete device by wiring³³ the components together with metallic conductors. It was no good (зд. Это не помогло): the more components and interactions, the less reliable the system.

The development of rockets and space vehicles³⁴ provided the final impetus⁶⁵ to study the problem. However, many attempts were largely unsuccessful.

What ultimately³⁶ provided the solution was the semicon­ductor integrated circuit, the concept³⁷ of which had begun to take shape a few years after the invention of the transistor. Roughly between 1960 and 1963 a new circuit technology became a reality. It was microelectronics development that solved the problem.

The advent³⁸ of microelectronic circuits has not, for the most part, changed the nature of the basic functional units: microelec­tronic devices are also made up of transistors, resistors, capacitors, and similar³⁹ components. The major difference is that all these elements and their interconnections are now fabricated on a single substrate⁴⁰ in a single series of operations.

II. Several key⁴¹ developments were required before the ex­citing potential of integrated circuits could be realized.

The development of microelectronics depended on the invention of techniques⁴² for making the various functional units on or in a crystal of semiconductor materials. In particular, a growing number of functions have been given over to circuit elements that perform best: transistors. Several kinds of microelectronic transistors have been developed, and for each of them families of associated circuit elements and circuit patterns⁴³ have evolved.

It was the bipolar transistor that was invented in 1948 by John Bardeen, Walter H.Brattain and William Shockley of the Bell Telephone Laboratories. In bipolar transistors charge carriers of both polarities are involved⁴⁴ in their operation. They are also known as junction⁴⁵ transistors. The npn and pnp transistors make up the class of devices called junction transistors.

A second kind of transistor was actually conceived almost 25 years before the bipolar devices, but its fabrication in quantity did not become practical until the early 1960's. This is the field-effect transistor. The one that is common in microelectronics is the metal-oxide-semiconductor field-effect transistor. The term refers⁴⁶ to the three materials employed in its construction and is addreviated MOSFET.

The two basic types of transistor, bipolar and MOSFET, divide microelectronic circuits into two large families. Today the greatest density of circuit elements per chip⁴⁷ can be achieved with the newer MOSFET technology.

An individual integrated circuit (1C) on a chip now can em­brace (включать) more electronic elements than most complex piece of electronic equipment that could be built in 1950.

In the first 15 years since the inception of integrated circuits, the number of transistors that could be placed on a single chip (with tolerable⁴⁸ yield⁴⁹) has doubled every year. The 1980 state of art⁵⁰ is about 70K density per chip. Nowadays we can put a million transistors on a single chip.

The first generation of commercially produced microelec­tronic devices are now referred to as small-scale integrated circuits (SSI). They included a few gates.⁵¹ The circuitry defining⁵² a logic array⁵³ had to be provided by external conductors.

Devices with more than about 10 gates on a chip but fewer than about 200 are medium-scale integrated circuits (MSI). The upper boundary⁵⁴ of medium-scale integrated circuits technology is marked⁵⁵ by chips that contain a complete arithmetic and logic unit. This unit accepts as inputs two operands and can perform any one of a dozen or so operations on them. The operations in­clude additions, subtraction, comparison, logical "and" and "or" and shifting⁵⁶ one bit to the left or right.

A large-scale integrated circuit (LSI) contains tens of thou­sands of elements, yet each element is so small that the complete circuit is typically less than a quarter of an inch on a side.

Integrated circuits are evolving from large scale to very-large-scale (VLSI) and wafer-scale integration (WSI).

The change in scale can be measured by counting the number of transistors that can be fitted⁵⁷ onto a chip.

Continued evolution of the microcomputer will demand fur­ther increases in packing⁵⁸ density.

There appeared a new mode⁵⁹ of integrated circuits, mi­crowave integrated circuits. In broadest sense,⁶⁰ a microwave in­tegrated circuit is any combination of circuit functions which are packed together without a user accessible⁶¹ interface.

The evolution of microwave integrated circuits must begin with the development of planar⁶² transmission lines.⁶³

As we moved into the 1970's, stripline and microstrip assem­blies became commonplace and accepted as the everyday method of building microwave integrated circuits. New forms of transmis­sion lines were on the horizon, however. In 1974 new integratedcircuit components in a transmission line called fineline appeared. Other more exotic techniques, such as dielectric waveguide⁶⁴ inte­grated circuits emerge.⁶⁵ Major efforts currently are directed at such areas as image guide, co-planar waveguide, fineline and di­electric waveguide, all with emphasis on techniques which can be applied to monolithic integrated circuits. These monolithic circuits encompass all of the traditional microwave functions of analog circuits as well as new digital applications.

Microelectronic technique will continue to displace other modes. As the limit of optical resolution⁶⁶ is now being reached, new lithographic and fabrication techniques will be required. Circuit patterns will have to be formed with radiation having wavelength shorter than those of light, and fabrication techniques capable of greater definition will be needed.

Electronics has extended⁶⁷ man's intellectual power. Microelectronics extends that power still further.