Page 36 - A Practical Guide from Design Planning to Manufacturing

12 Chapter One

Silicon transistors were cheap enough and reliable enough to allow
designs using hundreds or thousands of them. At that point the biggest
roadblock to using more transistors became making all the connections
between them. At this time hundreds of transistors could be made on a
single 1-inch silicon wafer. The wafer was then cut up into individual
transistors, and leads were soldered by hand onto each one. After being
sold to customers, the packaged transistors would then be soldered
together, again by hand, to form the needed circuit. It wouldn’t take long
for the market for transistors to become limited by the difficulty of
assembling them into useful products. The first person to conceive of a
solution to this bottleneck was Jack Kilby at Texas Instruments.
Kilby had already been working with transistors for a number of
years when he started work at Texas Instruments in May 1958. At that
time everyone at TI took time off work in July, but Kilby hadn’t been with
the company long enough to qualify for vacation. He spent his time
alone in the lab thinking about how to make it easier to assemble com-
plicated circuits from transistors. The idea occurred to him that perhaps
all the components of the circuit could be integrated into a single piece of
semiconductor. By September Kilby had constructed the first Integrated
Circuit (IC). All the computer chips of today are realizations of this
simple but revolutionary idea.
A few months later at Fairchild Semiconductor, Bob Noyce had the
same idea for an integrated circuit, but he carried the idea even further.
Constructing the components together still left the problem of making
the needed connections by hand. Noyce imagined simultaneously making
not only transistors but the wires connecting them as well. Silicon nat-
urally forms silicon dioxide (the main ingredient in glass) when exposed
to air and heat, and silicon dioxide is an excellent insulator. By grow-
ing a layer of silicon dioxide on top of a silicon chip, the components could
be isolated from wires deposited on top. Acid could be used to cut holes
in the insulator where connections needed to be made. By enabling the
fabrication of both transistors and wires as a single, solid structure, Noyce
made Kilby’s idea practical. All modern integrated circuits are made in
this fashion.
Fairchild Semiconductor and Texas Instruments both filed for patents.
Kilby had the idea first and created the first working integrated circuit.
Noyce’s idea of including the wiring on the chip made real products pos-
sible. The legal battle of who invented the integrated circuit would con-
tinue for 11 years after Kilby first had his insight. However, Noyce and
Kilby, both men of fair and generous natures (and from whom William
Shockley could have learned a great deal), consistently acknowledged
the importance of the other’s contribution.
For either company there was the chance of obtaining sole rights to
one of the most lucrative ideas in history, or being cut out of the business