{"id":4668,"date":"2022-08-26T10:00:00","date_gmt":"2022-08-26T10:00:00","guid":{"rendered":"https:\/\/modernsciences.org\/staging\/4414\/?p=4668"},"modified":"2022-08-11T06:53:11","modified_gmt":"2022-08-11T06:53:11","slug":"what-is-a-semiconductor-an-electrical-engineer-explains-how-these-critical-electronic-components-work-and-how-they-are-made","status":"publish","type":"post","link":"https:\/\/modernsciences.org\/staging\/4414\/what-is-a-semiconductor-an-electrical-engineer-explains-how-these-critical-electronic-components-work-and-how-they-are-made\/","title":{"rendered":"What is a semiconductor? An electrical engineer explains how these critical electronic components work and how they are made"},"content":{"rendered":"\n
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\n A silicon disc, or \u2018wafer,\u2019 yields dozens of semiconductor chips.\n Steve Jurvetson\/Wikimedia Commons<\/a>, CC BY<\/a><\/span>\n <\/figcaption>\n <\/figure>\n\nTrevor Thornton<\/a>, Arizona State University<\/a><\/em><\/span>\n\n

Semiconductors are a critical part of almost every modern electronic device, and the vast majority of semiconductors are made in Tawain. Increasing concerns over the reliance on Taiwain for semiconductors \u2013 especially given the tenuous relationship between Taiwan and China \u2013 led the U.S. Congress to pass the CHIPS and Science act in late July 2022. The act provides more than US$50 billion in subsidies to boost U.S. semiconductor production and has been widely covered in the news. Trevor Thornton<\/a>, an electrical engineer who studies semiconductors, explains what these devices are and how they are made.<\/em><\/p>\n\n

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\n Thin, round slices of silicon crystals, called wafers, are the starting point for most semiconductor chips.<\/span>\n Hebbe\/Wikimedia Commons<\/a><\/span>\n <\/figcaption>\n <\/figure>\n\n

1. What is a semiconductor?<\/h2>\n\n

Generally speaking, the term semiconductor refers to a material \u2013 like silicon \u2013 that can conduct electricity much better than an insulator such as glass, but not as well as metals like copper or aluminum. But when people are talking about semiconductors today<\/a>, they are usually referring to semiconductor chips.<\/p>\n\n

These chips are typically made from thin slices of silicon with complex components laid out on them in specific patterns. These patterns control the flow of current using electrical switches \u2013 called transistors \u2013 in much the same way you control the electrical current in your home by flipping a switch to turn on a light. <\/p>\n\n

The difference between your house and a semiconductor chip is that semiconductor switches are entirely electrical \u2013 no mechanical components to flip \u2013 and the chips contain tens of billions of switches<\/a> in an area not much larger than the size of a fingernail.<\/p>\n\n

2. What do semiconductors do?<\/h2>\n\n

Semiconductors are how electronic devices process, store and receive information. For instance, 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 them 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.<\/p>\n\n

\n \"A<\/a>\n
\n This schematic of a semiconductor chip shows many different materials in different colors and the complicated layering involved in producing a modern chip.<\/span>\n Cepheiden\/Wikimedia Commons<\/a>, CC BY<\/a><\/span>\n <\/figcaption>\n <\/figure>\n\n

3. How do you build a semiconductor chip?<\/h2>\n\n

The starting point for the vast majority of semiconductors is a thin slice of silicon called a wafer. Today\u2019s wafers are the size of dinner plates and are cut from single silicon crystals<\/a>. Manufacturers add elements like phosphorus and boron<\/a> in a thin layer at the surface of the silicon to increase the chip\u2019s conductivity. It is in this surface layer where the transistor switches are made. <\/p>\n\n

The transistors are built by adding thin layers of conductive metals, insulators and more silicon to the entire wafer, sketching out patterns on these layers using a complicated process called lithography<\/a> and then selectively removing 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 add materials in layers and then carefully remove unwanted material than it is to place microscopically thin lines of metal or insulators directly onto the chip. By depositing, patterning and etching layers of different materials dozens of times, semiconductor manufacturers can create chips with tens of billions of transistors per square inch.<\/p>\n\n

4. How are chips today different from the early chips?<\/h2>\n\n

There are many differences, but the most important is probably the increase in the number of transistors per chip.<\/p>\n\n

Among the earliest commercial applications for semiconductor chips were pocket calculators<\/a>, which became widely available in the 1970s. These early chips contained a few thousand transistors. In 1989 Intel introduced the the first semiconductors to exceed a million transistors on a single chip<\/a>. Today, the largest chips contain more than 50 billion transistors. This trend is described by what is known as Moore\u2019s law<\/a>, which says that the number of transistors on a chip will double approximately every 18 months.<\/p>\n\n