Scientist Discovers Physics Involved in Etching of Silicon Computer Chips

The physics involved in making the etching of silicon computer chips possible has been partially uncovered by Physicist Igor Kaganovich at the Department of Energy’s (DOE) Princeton Plasma Physics Laboratory (PPPL) together with collaborators.

Silicon computer chips are used to power computers, cell phones, and a wide range of electronic devices. The team specifically discovered how electrically charged gas called plasma makes the etching process more efficient that it would otherwise be. The research supported by the DOE’s Office of Science (FES) has been featured in two papers appearing in the September and December 2016 issues of Physics of Plasmas.

Kaganovich, Deputy Head of the PPPL Theory Department, and Dmytro Sydorenko of the University of Alberta, were aware that the plasma etching process was effective, but were not sure on the exact working of the process. So, they investigated the theoretical underpinnings of the process.

A piece of silicon is placed in a chamber and then immersed within a thin layer of plasma, almost two centimeters wide, during the etching process. Two electrodes are spaced a couple of centimeters apart within the plasma. These electrodes produce a beam of electrons.

A process called two-stream instability starts when electrons flow through the plasma. This process excites plasma waves that allow the plasma to etch the silicon in a more effective manner.

This process was modeled by Sydorenko and Kaganovich who illustrated that the waves developed by the electron beam can become increasingly more intense than in plasmas that are not bounded by electrodes. In other words, the wave driven by the two-stream instability can become extremely strong when a plasma is bounded.

The simulations indicate that the placing of plasma within a pair of electrodes supports the excitation of large plasma waves, which then lead to the acceleration of plasma electrons that can aid etching.

Igor Kaganovich, Physicist, DOE PPPL

Researchers would be able to design more efficient processes for etching circuits on silicon chips by enhancing their understanding of the physics undergirding the plasma etching technique.

PPPL, on Princeton University’s Forrestal Campus in Plainsboro, N.J., is focused on developing new knowledge about the physics of plasmas, ultra-hot, charged gases, and also coming up with practical solutions for the creation of fusion energy.

The Laboratory is administered by the University for the U.S. Department of Energy’s Office of Science, which is considered to be the largest single supporter of basic research in the physical sciences in the United States, and is also working towards addressing a few of the extremely pressing challenges that are currently available.