Integrated microcircuits come in

The question arises: what is the reason for cutting the wafer into separate transistors and then placing each of them into a separate case and joining these with wires into an electric circuit? Couldn't the transistors or other radio elements be joined together right inside the crystal?

The thing is that² digital calculators are assembled from just a few types of elements, viz. transistors, resistors, semiconductor diodes and capacitors. But each of these elements in one calculator circuit can occur hundreds of thousands of times. The planar technology allows to form all these elements and the elements substituting for connecting wires in one crystal.

The greatest advantage of planar technology is the possibil­ity of packing several thousands of various elements into one crystal to be joined into a circuit- The latter is intended for per­forming certain functions, for instance, conversion of the signals received or d'ata storage. Hence comes the integrated micro-circuit. This is a circuit manufactured as a single package, a mon­olithic integrated circuit which has alt the circuit components manufactured into and onto a chip of a semiconductor material.

In 1953 Harwick Johnson of the RCA³ applied for a patent on a phase-shift oscillator fashioned in a single piece of germanium by a planar technique. It was extended at Fairchild Semiconductor Company as follows: the integrated circuit accomplishes the separation and interconnection of transistors and other circuit elements electrically rather than physically. The separation is accomplished by introducing p-n diodes, or rectifiers, which allow the current to flow only in one direction.

The interconnection is realized by a conducting film of evapo­rated metal that is photoengraved to leave the appropriate pattern of connections. An insulating layer is required tu separate the underlying semiconductor from the metal film except where electric,

' manufacturing yield — выход готовой продукции '^г The thing is that —Дело в том, что ³ RCA = Radio Corporation of America

10

contact is desired- The inventors of this basic technique were two American engineers, J. S. Kilby and R. N. Noyce (1960).

Our scientists A. F. loffe, Y. I. Frenket and B. I. Davydov have made an invaluable contribution to the semiconductor theory. Great is the number of talented Soviet engineers who have created the up-to-date semiconductor technology. There are all kinds of computers using failure-free microelectronics, from those operating in cosmic stations to school minicomputers.

Microelectronics makes rapid progress

Thus the basic methods of planar technique were available by 1960, and the era of the integrated circuits was introduced. It has made an astonishing progress since then. An individual integrated circuit on a chip perhaps a quarter of an inch square can now embrace more electronic elements than the most complex piece of electronic equipment that could be built in 1950. For example, today's microcomputer based on integrated circuits has more computing capacity than the first large electronic computer ENIAC- It is twenty times faster, has a larger memory, is thousands of times more reliable, consumes the power of a light bulb rather than' that of a locomotive (and such was the power of ENIAC), occupies 1/30.000 the volume and costs 1/10,000 as much.•

Today integrated circuits containing 2'⁸ (262.144) elements are available and their complexity continues to double every year. The costs of microelectronics would continue to decrease and we have not yet seen any significant departure from this law.

The substitution of microelectronic devices for discrete com­ponents reduces costs not only because the devices themselves are cheaper but for a variety of other reasons. First, the integrated circuit contains inside it many of the interconnections that were previously required and that saves labours and materials. The interconnections of the integrated circuits are much more reliable than the ..solder joints of connectors of discrete components. Microcircuits are much smaller and consume much less power than the components they have displaced. Less testing is needed in .the course of production. Finally, the user needs to provide less floor.space, less operating power, less air conditioning for the equipment.

All the above-mentioned savings motivate the wide-range use of the integrated microcircuits- As the number of components per chip increased and correspondingly the price per component decreased, a shift in the mode² of designing electronic micro-circuits occurred. In the past, operations were predominantly

' rather (han — а не ² shift in the mode — изменение способа

carried out in the "analogue" mode, that is the output of the elec­tronic circuit was proportional to the intensity of the property being represented. An example is the audio-amplifier:' at any instant uf time² the voltage at the output terminals is proportional to the amplitude of the sound being amplified and reproduced.

A LUCKY MEETING AT THE TECHNOLOGICAL CROSSROADS

The modern trend of microcircuits for more and more applica­tions is the "digital-logic" mode of operation³ In this mode, the input signal is first converted into a binary number or a sequence of numbers and the output signal consists of another sequence of numbers logically related to the input signal. The final output can, of course, be amplified to actuate various devices, such as servomotors, loudspeakers or the numerical display⁴ of the computer.

Logic chips were employed for control or arithmetic function, in specialized applications, and also to build microcalculators.

In what became known as "hardwired logic"⁵ systems, chips and other individual components were soldered into a rigid pattern on a so-called printed-circuit board⁶ The fixed interconnections served as the program prototype of the microelectronic computer. Curiously, it was even less flexible than ENlAC's primitive array of plug-in wires⁷ that could be moved around to change the program.

The trend towards digital "logic" operations is symptomatic of the very close relationship between microelectronics, i. e. micro­circuits, and computers. The semiconductor logic circuit, of course, contained the seed of the microcomputer since the chip had logic elements built around the transistors.

It may be said that the development of modern computers was entirely dependent upon developments in integrated circuits, but also that modern integrated circuits developed in directions largely determined by computers.