Semiconductors and Transistors

Semiconductors and Transistors

Semiconductors, often called integrated circuits, chips or microchips, are essential components of all computers and are used in a wide variety of other devices including telecommunications equipment, consumer electronics, home appliances, and even automobiles. In fact, chips have found their way into an increasing number of products over the past decade, adding functions to existing products and making possible the creation of new ones. These new uses helped the worldwide semiconductor industry grow to almost $200 billion in sales in 1995. The Canadian microelectronics industry was approaching $1 billion in annual sales in 1995.

Uses

The rapid pace of technological change in semiconductors (every year or 2 their capacity doubles while prices are halved) permits them to be used not only in sophisticated electronic systems but also in many consumer products (eg, personal computers, calculators, video games, cars, sewing machines, videocassette recorders and microwave ovens).

Chips in consumer electronics products have created entirely new capabilities, such as the modern compact-disc player's ability to play all the individual selections on several different discs in random order without repeating a track, or a radio tuner's ability to scan the frequency spectrum until it locates an audible station. Chips in cars make possible such features as braking systems that "pump" brakes on and off on slippery roads, reducing the danger of a skid.

Chips have also made possible the creation of new consumer products, such as smart cards, whose embedded microprocessors and memory allow them to be used for paying bills on the spot at retail counters, for making calls from pay telephones without rummaging for a quarter, or for security and access control. However, computer manufacturers are the biggest buyers of chips. Personal computers alone account for roughly half the sales of chips worldwide.

Structure

The basic building block of the integrated circuit is the transistor, developed by AT&T Co's Bell Laboratories in 1948. A transistor is an electronic switch that controls electric signals passing through the chip. An integrated circuit is a wafer of silicon on which multiple transistors are laid out in intricate patterns - patterns that have become denser and more complex each year since the US firms Texas Instruments and Fairchild Semiconductor built the first integrated circuits in 1959.

Chipmakers continue to squeeze increasing numbers of transistors onto chips about the size of a thumbnail. Chips containing tens of thousands of transistors are called large-scale integration (LSI) chips, while those with hundreds of thousands to millions of transistors are called very large-scale integration (VLSI) chips. In the early 1980s, chips with about 250 000 transistors were the latest in semiconductor technology. Intel Corp's Pentium Pro microprocessor, brought to market in 1999 and powering the latest personal computers manufactured today, has 5.5 million transistors.

Technologies based on VLSI chips are faster and more reliable, smaller and more portable, cheaper and more energy efficient than those just a generation older. It has been estimated that a product with 10 standard chips will cost 2-3 times more to produce than one using a VLSI chip. The price of computers and other electronics products often drops sharply when custom chip sets, designed to integrate the necessary electronics onto fewer integrated circuits, come to market. Thus custom and semicustom chips designed to perform specialized functions are growing in importance.

Standard or "off-the-shelf," general-purpose chips dominated in the 1970s and 1980s. Custom chips, also known as application-specific integrated circuits (ASICs) began gaining popularity during the 1980s. A subset of these, semicustom chips, has grown fastest, reaching sales of about $7.94 billion in 1994. They are made by combining a number of "cells" in novel ways to create chips that can do special tasks, or by using partially prefabricated chips for special functions. Semicustom chips are cheaper and less complicated to design and make than are full custom chips, sales of which in 1994 were about $3.72 billion. New technologies (eg, computer-aided design, automated assembly lines and ion-beam write-on-wafer devices) are expected to reduce greatly the cost of producing specialized chips.

Production

Chip production is divided into 2 phases: design and fabrication. The first is the most expensive and time-consuming: designing a VLSI chip can take several years and cost millions of dollars. Fabrication involves laying down the intricate patterns of transistors and their connections, often on several layers of silicon. Because of the very fine tolerances involved, highly sophisticated machinery is needed and the work must be done in carefully controlled areas known as clean rooms.

Chips are first produced in the form of wafers, usually 6 or 8 inches in diameter, and when complete the wafers are cut up to form individual chips. Despite all precautions, some of the resulting chips have flaws and must be discarded; the average number of good chips per wafer is known as the yield, and usually increases as a particular semiconductor technology matures.

Canadian Industry

Canada has only 3 wafer fabrication plants, or "wafer fabs." NORTHERN TELECOM LTD operates one in Nepean, Ont, MITEL CORP has one in Bromont, Qué, and Gennum Corp runs the third in Burlington, Ont. No new plants have been built here since the 1970s. However, a number of Canadian companies design chips that are then manufactured for them in foreign plants, often in the Far East. An example is ATI Technologies Inc, a Markham, Ont, company whose circuit designs provide graphics and other capabilities for personal computers. Northern Telecom also has many of its chip designs manufactured elsewhere, since its needs exceed the Nepean fab's capacity.

See also COMPUTER INDUSTRY; ELECTRONICS INDUSTRY.