The application of plasma diagnostics to process control

Summary form only given. The possibility of using plasma diagnostic tools to establish in-situ monitors to keep output capability high and allow real-time process control has been investigated. An initial study to examine this possibility was conducted on a tungsten etchback module on an LRC 490 etcher. The diagnostic tools used were an optical emission spectrometer, a residual gas analyzer, and a Langmuir probe. Five simple etch processes with different etch characteristics were selected as test vehicles. The etch performance of these processes was monitored with both traditional etch rate monitors and plasma parameters such as optical emission spectra, mass spectra, and ion saturation currents vs. the number of wafers processed through the etcher. The mass spectra and optical emission spectra show changes related to the drift in the process due to the chamber condition for only highly reactive processes. The ion saturation currents are not sensitive to the process drift in all cases.