2. What do semiconductors do?
Semiconductors are how electronic devices process, store and receive information. For example, memory chips store data and software as binary code, digital chips manipulate the data based on the software instructions, and wireless chips receive data from high-frequency radio transmitters and convert it into electrical signals. These different chips work together under the control of software. Different software applications perform very different tasks, but they all work by switching the transistors that control the current.
3. How do you build a semiconductor chip?
The starting point for the vast majority of semiconductors is a thin slice of silicon called a wafer. Today’s waffles are the size of plates and are cut from single silicon crystals. Manufacturers add elements such as phosphorus and boron in a thin layer on the surface of the silicon to increase the conductivity of the chip. It is in this surface layer where the transistor switches are made.
The transistors are built by adding thin layers of conductive metals, insulators and more silicon to the entire wafer, sketching patterns on these layers using a complicated process. called lithography and then selectively remove these layers using computer-controlled plasmas of highly reactive gases to leave specific patterns and structures. Because the transistors are so small, it is much easier to layer materials and then gently remove unwanted material than to place microscopic thin lines of metal or insulators directly on the chip. By layering, patterning and etching different materials dozens of times, semiconductor manufacturers can create chips with tens of billions of transistors per square inch.
4. How do the current chips differ from the early chips?
There are many differences, but the most important is probably the increase in the number of transistors per chip.
Among the earliest commercial applications for semiconductor chips were: pocket calculators, which became widely available in the 1970s. These early chips contained a few thousand transistors. In 1989, Intel introduced the the first semiconductors with over a million transistors on a single chip. Today, the largest chips contain more than 50 billion transistors. This trend is described by what is known as: Moore’s Lawstating that the number of transistors on a chip will double approximately every 18 months.
Moore’s Law has been around for five decades. But in recent years, the semiconductor industry had to overcome great challenges-mainly, how the size of transistors can continue to shrink – to continue this pace of progress.
One solution was to switch from flat, two-dimensional layers to three-dimensional layers with fin-shaped ridges of silicon protrude above the surface. These 3D chips have significantly increased the number of transistors on a chip and are now in widespread usebut they are also much more difficult to manufacture.
5. Do more complicated chips require more sophisticated factories?
Simply put, yes, the more complicated the chip, the more complicated and expensive the factory.
There was a time when almost every American semiconductor company built and maintained its own factories. But today a new foundry can cost over $10 billion to build. Only the largest companies can afford that kind of investment. Instead, most semiconductor companies send their designs to independent foundries for production. Taiwan Semiconductor Manufacturing Co. and GlobalFoundries, headquartered in New York, are two examples of multinational foundries that build chips for other companies. They have the expertise and economies of scale to invest in the hugely expensive technology needed to produce the next generation of semiconductors.
Ironically, although the transistor and semiconductor chips were invented in the US, there are currently no state-of-the-art semiconductor foundries on US soil. The US has been here before in the 1980s when there were concerns that Japan would dominate the global memory business. But with the recently passed CHIPS Act, Congress has provided the incentives and opportunities for next-generation semiconductor manufacturing in the U.S.
Perhaps the chips in your next iPhone are “designed by Apple in California, built in the USA”.
Trevor Thornton is a professor of electrical engineering at Arizona State University.