“…34 However, filament discharges are incompatible with most of the equipments used for micro-and nanoelectronic industry. Recently, a new type of ECR plasma source was build, namely, the multidipolar ECR, [36][37][38] which allows one to produce an easy scalable plasma source in various configurations, free of magnetic field in plasma volume, operating even below 10 mTorr. From the point of view of industrial applications, a negative ion plasma source that can provide the following characteristics is desirable: no contamination by filaments, no density jumps; negligible magnetic field in plasma volume; a density ratio of negative ion to electron higher than 50 (as to make it possible to bias the substrate positively without affecting the plasma potential, V pl , and to avoid overheating by electrons 33,34 ); stable operation at low pressure with no plasma potential drift; 34 good controllability of ion species and high etching rates.…”