New diagnostic method for monitoring plasma reactor walls: Multiple total internal reflection Fourier transform infrared surface probe

Films and adsorbates that deposit on reactor walls during plasma etching an d deposition affect the discharge properties such as the charged particle a nd reactive radical concentrations. A systematic study of this plasma-wall interaction is made difficult by a lack of diagnostic methods that enable o ne to monitor the chemical nature of the reactor wall surface. A new diagno stic technique based on multiple total internal reflection Fourier transfor m infrared (MTIR-FTIR) spectroscopy was developed to monitor films and adso rbates on plasma etching and deposition reactor walls with monolayer sensit ivity. Applications of this MTIR-FTIR probe are demonstrated. Specifically, we use this probe to (i) detect etch products and films that deposit on th e reactor walls during Cl-2 plasma etching of Si, (ii) determine the effica cy of a SF6 plasma to clean films deposited on reactor walls during Cl-2/O- 2 etching of Si, and (iii) monitor wafer-to-wafer etching reproducibility. (C) 2001 American Institute of Physics.