From Beach Sand to Semiconductors: How Computer Chips are Made

Computer chips are in the news today because they are in short supply, which is causing widespread global disruptions   Why can’t we just manufacture more chips?

The short answer is that making computer chips is incredibly complicated. Chip fabrication facilities are running full blast, but that still isn’t enough to satisfy the voracious global demand. There are few manufacturers capable of meeting the soaring demand for highly advanced chips, and these suppliers were caught off guard by the massive global pandemic-driven surge in demand for more computer processing power.  With millions of products from cars to smartphones to washing machines reliant on these postage stamp-sized computing powerhouses, entire end-product production lines had to come to a standstill and legions of consumer products became unavailable.

What exactly is a computer chip?

A computer chip is a packaged set of electronic circuits printed onto a thin, circular wafer made of the element silicon, one of the most abundant elements in the earth’s crust. These electronic circuits work with the help of transistors, which serve as tiny switches that turn an electrical current on or off. These operations are the basis for all modern computing.

The first commercially available computer chip was the Intel 4004 microprocessor, released in 1971. It consisted of 2,300 transistors and was one of the first to use silicon gate technology, which made it possible to increase the circuit density fivefold compared to previous computer chips.

By comparison, Intel’s 12th-generation i9-12900K CPU contains 3 billion transistors, each one only 7 nanometers in width (a nanometer is one billionth of a meter). Apple’s M1 Max chip, developed for the MacBook Pro, is even more impressive, containing 114 billion transistors built on the 5-nanometer scale. That’s about one-fourth the size of the smallest viruses- only 50 times larger than a single hydrogen atom!

Computer chips serve a variety of different purposes, but they broadly fall into four categories. There are microprocessors (also known as central processing units or CPUs), memory chips (used for short-term storage of digital data), graphical processing units (GPUs), and commodity integrated circuits (CICs) used in single-purpose appliances such as barcode scanners.

How is a computer chip made?

Silicon is the chief ingredient in all modern computer chips because of its ability to act as either a conductor or an insulator of electrical current.  Silicon is also readily available and extremely cheap, since it is the main ingredient in beach sand.

While we often hear about the ongoing shortage of silicon, what we really mean is the shortage of silicon chips. There are very few manufacturers with the capacity to build silicon chips at the incredibly small nanometer scale, and this production challenge is only growing as these chips get smaller every year while the demand for them continues to explode.

Manufacturing tools like precision lathes and 3D printers can create intricate designs, but they become ineffective beyond micrometer levels of precision. This makes them unsuitable for assembling computer chips.

Because their transistors and interconnections are so small, computer chip manufacture requires a process known as photolithography, which uses light to etch images onto a silicon wafer coated with a photo-resistant material. Once a schematic of the chip has been etched onto the silicon, the etching is filled with various metals and then doped to create transistors. Doping is a process that adds precise levels of impurities such as boron, aluminum, indium, arsenic, or antimony to the silicon to alter its electrical properties and create the minuscule components of a computer chip.

This photolithography process can be repeated many times to create multiple layers of electronic components on the silicon wafers. Modern chips may have many dozens of layers to fit as many transistors as possible into the smallest possible space. However, there is a tradeoff between the growing number of component layers and the increasing amounts of heat they generate, because too much heat will cause degradation of computing performance.

Once all these layers are complete, the chip must be thoroughly tested to ensure that it conforms to its design requirements. The term Yield refers to the percentage of chips that pass these tests and, as a result, aren’t discarded or downgraded to conform to lower specifications. Depending on the manufacturer, a yield of at least 90% is considered ideal.

After fabrication, the silicon wafers are transformed into usable computer chips. To accomplish this the wafers are sliced into small units called dies, which must then be packaged to create a computer chip. The tiny postage-stamp-sized die are individually attached to a substrate equipped with electrical connections and the entire assembly is then encapsulated. The electrical connections, which come in a variety of types, connect the computer chip to the rest of the computer system once it is installed in a CPU socket, memory slot, or another interface in a computer or other digital device.

Naturally, the entire computer chip manufacturing process must occur in a clean room engineering space, since even the tiniest microscopic contaminants can immediately ruin the chips being produced. After all, the level of precision required is many orders of magnitude smaller than the human eye can perceive.

Which companies make computer chips?

The world’s biggest chip manufacturers are household names like Samsung and Intel, while numerous other companies manufacture embedded chips for myriad other devices, such as smartphones, vehicles, and internet-connected smart tech.

The semiconductor supply chain broadly consists of three main players:

• Integrated device manufacturers (IDMs) design, manufacture, and sell their own computer chips
• “Fabless” semiconductor firms design and sell chips, but outsource manufacturing
• Pure play foundries manufacture only and sell to the IDMs and fabless semiconductor companies