High-VHF Capacitive-Coupled-Plasma Technology, with Scaling to 450mm

摘要

Process demands on plasma etch have forced the development and introduction into manufacturing of new plasma technology. These process demands have, historically, been driven by device-scale shrinkage, and over the last decade the introduction of new material into the device stack and changes in photo-resist materials. The future devices will require tighter process control, adaptability to radical changes in materials, structures, and accommodating needs for process integration. In addition, factory economics is bringing in 450mm wafer size. One of the notable developments over the last 10 years has been the increased frequency of capacitively coupled plasma systems to include 100MHz and 162MHz. However, while further increases in frequency have been shown to provide improved process performance, they suffer from process non-uniformity due to wavelength effects. This has severe implications for 450mm tool development as frequencies will have to be reduced with resultant drop in performance and/or process window. Multi-tile plasma sources provide a solution, enabling substantially higher frequencies and enable scaling to large areas including 450mm wafers. The implications on the rf subsystem and the technical advantages of a novel class of divide-by-arbitrary-N power splitter is presented.