Cleaning chamber walls after ITO plasma etching process

The integration of new materials in the next generation of optoelectronic devices leads to several challenges. For instance, the etching of indium tin oxide (ITO, In2O3:Sn) faces the issue of the low volatility of In- and Sn-based etch products at room temperature. This is challenging for the etching process itself, but even more problematic when the inductively coupled plasma (ICP) reactor must be cleaned after etching: since the reactor walls are bombarded by low energy ions only, the removal of In- and Sn-based products redeposited on the walls can be very long and laborious. Therefore, we have investigated several plasma chemistries to find the most efficient reactor cleaning process suitable for ITO plasma etching. The results show that after ITO plasma etching the walls are indeed contaminated by indium. At the low temperature at which the reactor walls are regulated, BCl3/Cl-2 cleaning plasma is ineffective to remove this deposit while HBr and CH4/Cl-2 chemistries provide promising results.