IEEE Spectrum December, 2007 - 40

S E MI c o N D u c t o r S

The
Silicon
Dioxide
Solution
How physicist Jean Hoerni built the bridge from the transistor
to the integrated circuit By MICHAEL RIORDAn

Not plastic bags, nor metal screws, nor cigarette butts. No, the
commonest human artifact today is the transistor-invented
60 years ago this month by Bell Labs physicists John Bardeen and
Walter Brattain. Millions of these subminiature switches populate computers, cellphones, toys, domestic appliances, and anything else that carries a microchip. Exactly how many transistors
are around is hard to know, but several years ago Gordon Moore,
a founder of Intel Corp. and author of the famed Moore's Law,
made an educated guess: more than 1018-that's one quintillion-
transistors are produced annually. "We make more transistors per
year than the number of printed characters in all the newspapers,
magazines, books, photocopies, and computer printouts," Moore
told me recently. "And we sell these transistors for less than the
cost of a character in the Sunday New York Times."
Behind the explosive growth that transistor production has
seen since 1960 is a major technological achievement. Today,
chipmakers essentially print transistors on silicon wafers. It's a
manufacturing method rooted in the mechanical printing process originated by Johannes Gutenberg more than 500 years ago-
though far more complex, of course. Moore himself played a lead
role in developing transistor-fabrication technology during the
1960s when he was research director at Fairchild Semiconductor
Corp., in Palo Alto, Calif. But much of the credit for that revolutionary advance belongs to a lesser-known semiconductor pioneer and Fairchild cofounder. The unsung hero of this pivotal
chapter in the history of electronics-the invention of the planar
transistor-is Jean Hoerni.
A Swiss-born theoretical physicist, Hoerni, along with seven
other determined, like-minded rebels-Moore, Robert Noyce, Jay
Last, Sheldon Roberts, Eugene Kleiner, Julius Blank, and Victor
Grinich-founded Fairchild in 1957 [see photo, "The Fairchild
Eight"]. They all contributed, directly or indirectly, to the new

technology, but none so much as Hoerni [see photo, "Practical
Theorist"]. Fifty years ago, sitting alone in his office, he elaborated a radically new kind of transistor: a more compact, flatter device whose sensitive parts were protected beneath a thin
layer of silicon dioxide. Hoerni's brilliant idea, more than any
other single factor, allowed the fledgling firm to begin printing
transistors on silicon. Planar transistors would prove to be much
more reliable and perform far better than other designs, in effect
rendering the competition's offerings obsolete.
The planar process also made it easy to interconnect neighboring transistors on a wafer, paving the way to another Fairchild
achievement: the first commercial integrated circuits. As other
companies realized the great advantages of planar technology
and began adopting it on their own production lines, Hoerni's
elegant idea helped to establish Silicon Valley as the microelectronics epicenter of the world.

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HE fInAL MOnTHS Of 1957 were a time of anticipation at Fairchild as the founders organized the new
firm's labs and production lines in a group of buildings at 844 Charleston Road in Palo Alto. In September
of that year, the eight scientists and engineers had
resigned en masse from Shockley Semiconductor Laboratory,
in Mountain View, about 2 kilometers away. They were rankled
by the heavy-handed management style of its founder, transistor pioneer William Shockley, and his pursuit of difficult R&D
projects at the expense of useful, salable products. So they persuaded the Fairchild Camera and Instrument Corp. of Syosset,
N.Y., a firm looking to diversify its business, to found Fairchild
Semiconductor. The eight founders planned to use the silicon
processing techniques they'd learned under Shockley to make
and sell advanced, high-speed transistors.

December 2007 | IEEE Spectrum | NA 51

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Table of Contents for the Digital Edition of IEEE Spectrum December, 2007