Current Applied Physics, Vol.20, No.4, 550-556, 2020
Absolute density measurement of hydrogen atom in inductively coupled Ar/H-2 plasmas using vacuum ultraviolet absorption spectroscopy
The absolute density measurement of atomic species such as hydrogen is crucial for plasma processing because of their strong chemical reactivity. In this work, to measure the hydrogen atom density in Ar/H(2 )inductively coupled plasmas (ICP), the self-absorption-applied vacuum ultraviolet absorption spectroscopy (VUVAS) is studied with a micro-hollow cathode H-2/He discharge lamp (MHCL) emitting VUV light (Lyman alpha line; L-alpha 121.56 nm). The absolute density of hydrogen atoms in the ICP is investigated for various powers (50 W-850 W) in the low pressure region (30 mTorr-50 mTorr). The hydrogen density in remote plasma region is shown to vary from 2.1 x 10(11) cm(-3) to 1.25 x 10(12) cm(-3) with respect to plasma power.