Characterisation of an industrial plasma immersion ion implantation reactor with a Langmuir probe and an energy-selective mass spectrometer

Characterisation of an industrial plasma-immersion ion implantation (PIII) reactor developed by the French company Ion Beam Services (IBS) and our laboratory is presented. Nitrogen (N2) and boron trifluoride (BF3) plasmas were studied with a Langmuir probe and an energy-selective mass spectrometer. Plasma density between 107 and 1010 cm−3 is obtained in the reactor thanks to an inductively coupled plasma (ICP) source. The measurements have shown that N2+ (BF2+) was the most abundant ion in N2 (BF3) plasmas (>80%). The injected power has a great influence on the chemical composition of the plasma: the higher the power, the higher the density is, which induces greater decomposition of the gas molecules. The same effect is observed when the gas pressure increases, but in lower proportions. A time-resolved analysis of pulsed N2 plasmas is also presented, which shows similar temporal evolution for N+ and N2+ ions. Energetic ions (>40 eV) have been detected at the beginning of the pulse due to energetic electrons, which induce a high plasma potential in the first μs of the discharge.