Controlling a plasma afterglow to mitigate particle contamination in semiconductor manufacturing

Professor John Goree; Department of Physics and Astronomy, University of Iowa

Semiconductor manufacturing is the largest industry that makes use of recent plasma physics research. Silicon wafers are exposed to plasma to deposit thin films and to etch them. Plasmas are also used to make ion beams for implantation, and to make extreme ultraviolet light. In all these processes, there is a problem due to contamination of the wafer by solid particles, of micron size or smaller. Before they fall on the wafer, these particles are immersed in a plasma, causing them to be electrically charged. When the plasma is turned off, during the brief afterglow plasma, the particles fall and land on a valuable surface like a wafer, and contaminate it. Neeraj Chaubey and I have developed a mitigation scheme to control the particles to prevent them from falling onto the wafer. This scheme, and the underlying physics, will be the topic of this seminar.