CLEANING OF ELECTRON-BEAM-INDUCED CONTAMINATION IN THE ELECTRON-BEAM COLUMN

The parameters for cleaning of electron beam-induced carbon contamination were investigated. Reactive species of O2 and CF4 gas mixture were used for cleaning. By evaluating the photoresist film etch rate, the appropriate process and geometrical conditions for cleaning were obtained. Cleaning of the beam definition aperture, which was contaminated by the electron beam irradiation for 250 hours, was carried out at 0.22 Torr pressure for 20 minutes operation time. The gas flow rate were 200 sccm for O2 and 20 sccm for CF4. Complete removal of the contamination was confirmed.