Chapter 4. How Chips Are Made

In this chapter...

• Clean Rooms and Fabs

• Developing Technology: Chips and Photography

• Silicon Ingots to Start

• Polishing the Wafer Smooth

• Building the Layer Cake

• Laser Surgery: Etching Away the Transistors

• Step and Repeat

• Etching Bath

• Ready for the Metal Round

• Testing Phase I

• Bringing out the Diamonds

• Sorting the Fast From the Merely Good

• Wrap It Up

• How Many Nanometers in a Micron?

• Let's Get Small

Silicon chips are made in a process that's a combination of the familiar and the bizarre. Some aspects are as familiar as developing a few photographs, whereas others resemble space exploration or subatomic physics. In the end, it's all of these and the process gets stranger and more fascinating the more you learn about it. In this chapter we take a brief tour as a hypothetical chip we've designed makes its two-month journey through a chip factory.

Chips might seem small and flat, but they're really three-dimensional sandwiches 10 or 20 layers thick. It takes more than two dozen steps to build up this silicon sandwich, and plenty of things can go wrong along the way. It's not until near the end, however, that you discover whether the chip is any good or not. Chips destined for the trash can cost just as much to manufacture as those headed for new PCs, so quality control is important, and manufacturing secrets are closely guarded.

Many chip-making companies are well known, and firms like Intel, Motorola, and Texas Instruments get plenty of credit for advancing the industry, but it's really the behind-the-scenes companies that develop the chip-making equipment that deserve the glory. Companies like ASM Lithography, Applied Materials, and Ultratech Stepper (to name just a few) are responsible for moving the semiconductor industry forward at such a rapid pace. To some extent, the Intels of the world are only using the tools they're given. Without these exotic and leading-edge tools, our world of computers, satellite communications, and consumer electronics would not be where it is today, or where it is headed tomorrow.