Yaguang Lian has been a research engineer in the Holonyak Micro & Nanotechnology Lab for nearly 20 years. Part of his job is training students to fabricate semiconductor devices. In addition to fabrication processes, he teaches the underlying chemistry and physics needed to understand both the processes and the devices themselves. Students eventually asked him to write an accompanying text because the information he was teaching them is not readily available elsewhere. The result, Semiconductor Microchips and Fabrication, was published by Wiley last month.
Semiconductors are materials whose ability to conduct electricity falls between that of an insulator, such as rubber, and a true conductor, such as copper. However, it was discovered in the last century that these materials’ conductivity can be modified by a chemical process called doping. This capability has led to their use in microchips and sensors, the building blocks for all computers and electronics, and LEDs, the lighting components of electronic displays. These devices have shaped the modern world, and the University of Illinois Urbana-Champaign is central to their history.
“If we talk about semiconductors,” Lian noted, “we must talk about UIUC.”
The three pioneers of semiconductor devices—John Bardeen, who built the first transistor, a device vital to modern electronics, from doped semiconductors; Nick Holonyak, who invented LEDs; and Jack Kilby, who fabricated the first integrated circuit chip—were all students or faculty at the University of Illinois at some point in their careers. This rich tradition is partly why Lian moved from Los Angeles and accepted a position in HMNTL.
Semiconductor devices are so prevalent that Lian works with students from across The Grainger College of Engineering: not just from electrical and computer engineering but also mechanical and, to his surprise, civil engineering. He finds that many of the students who come to him, especially those outside electrical engineering, are unfamiliar with the underlying science. In addition to training users on the equipment, he explains how fundamental principles from chemistry and physics enter device fabrication and operation.
As he says in his book’s introduction, “It is not enough for you to know how to do it; you must know why to do it.”
However, Lian strives to keep the information accessible and relevant to the specific methods the student will use. He contrasts his instruction with existing texts which are written for academic researchers and trained process engineers. They heavily rely on theory, making them unapproachable to students who were never taught the chemistry and physics of semiconductors.
“Because I’m an engineer,” he said, “I understand what students need most to learn the process.”
Still, Lian believes that learning fabrication processes requires at least a working knowledge of the fundamental principles. He finds that, when newcomers are taught the basic theory alongside specific techniques, they have a much sounder understanding and begin to try things on their own. This is what he hopes to do with his text written to non-specialists: enable even more researchers and engineers to approach semiconductor device fabrication on their own and use it in their own work.