Why is Silicon Valley called Silicon Valley?

This history byte is a Weekly What Is dedicated to the why and where of a technology name.

When learning the geography of the American West Coast one realizes fairly quickly there are a lot of valleys. The San Fernando Valley, Santa Clara Valley, Death Valley, Mission valley, more than enough to go around. Most areas in the American west are named for the Spanish, who actively explored and settled the region. Yet there is one popular valley with a fairly strange name – Silicon Valley. Silicon is a metalloid, atomic number fourteen with an atomic weight of twenty-eight. The uses for silicon are varied, silicone grease can be used to lubricate a Rubix cube in order make it spin fast enough for use in a “speed cubing” competition, silica[1] gel packets are heavily relied upon to keep moisture out of packaging and silica is even used as a food additive. None of this however, explains why a tract of California is named after silicon; luckily this blog post will do just that.

Silicon Valley is called Silicon Valley because of sand. As a term it first appeared on the cover of the January 11^th edition of Electronic News Magazine in 1971. Don Hoefler a journalist for the publication had titled a three part series examining the history of the semiconductor “Silicon Valley U.S.A.” The term rapidly became associated with technology, in such a way that the two are now almost inseparable. But back to sand. There is a reason why Hoefler chose to title his articles on semiconductors after silicon. Many companies manufacturing computer chips (like Intel) were either operating or headquartered throughout the region, now known as Silicon Valley back, in 1971. The first ingredient in the manufacturing process of computer chips happens to be – sand.

Understandably the term “computer chip” might be a bit foreign but the truth is actually less complex than the name implies. Last week we went over the difference between hardware and software, this week we won’t be talking about software at all, which makes our lives much easier. We will only be examining hardware, and in the interest of clarity, one specific type of hardware – the Central Processing Unit (C.P.U). This is your computer’s engine; handling most of its functions and processes. Admittedly making a C.P.U is a bit of a strange process. Manufacturers first take silica sand and heat it up. Those familiar with the glass making process will see where this is going. When making glass the glassmaker will first take sand, put it in a crucible and heat it (usually over 3,000 degrees Fahrenheit). The melted sand is then shaped, blown and cooled, resulting in glass. The same process is the first step in creating a C.P.U. Silica sand is melted down and formed into an extremely pure mono-crystal[2]. The crystal is then cut into extremely thin wafers that are anywhere from one to twelve inches in diameter. The wafer is polished and cleaned of any impurities[3]. Wafers are meant to hold thousands of very small transistors. Transistors are at the foundation of electronic computing and deserve their own blog post (coming soon) but what is important to know here is that they are very tiny on off switches, like a sink faucet or a light switch. The process of putting transistors on silicon wafers is a complex chemical one; which is not entirely beneficial to learn if you’re not studying to enter the industry. The result the process is a wafer filled with transistors. Wafers are then tested for functionality and working sets of transistor are cut from it. These tiny rectangles, filled with transistors are the basis of your Central Processing Unit. The chip is then packaged in a housing that allows it to connect to your computer.

Silicon Valley takes its name from the large population of companies doing this work, headquartered or operating in the San Francisco Bay area. As with most technology terms, it evolved and stuck. Eventually coming to be a representation of the entire technology industry, due in part to a large influx of similar companies to the Bay Area during technology booms following 1971. Companies like eBay, Adobe, HP, Yahoo! and Lockheed Martin are still based in the Valley. The size of these Fortune 1000 companies is in stark contrast to where their home gets its name, tiny grains of sand.

[1] Silica is a silicone oxide, a chemical containing an atom of oxygen. It’s chemical Formula is SiO2 (Silicone Dioxide)

[2] “Mono-crystal” is referring to the silicon ingot that emerges from the Czochralski process. In the interests of simplicity and clarity this blog only discusses Czochralski based ingot making and not “Float Zone” growing methods.
An image of the resulting ingot

[3] An image of the resulting waver

“Weekly What Is” breaks down a new technology related word every Friday.