Experiment and global model of inductively coupled RF Ar/N$_2$ discharges

Plasmas containing N$_2$ have been attracted as a source of active species such as the active atomic nitrogen and the excited nitrogen molecules in the field of material science. In this study, measurements with a Langmuir probe and optical emission spectroscopy are carried out in inductively coupled RF (13.56 MHz) Ar/N$_2$ discharges in the total pressure range from 20mTorr to 100mTorr, changing the N$_2$ content from 5$\%$ to 50$\%$. Plasmas are produced in the cylindrical stainless steel chamber with 160 mm in inner diameter and 40 mm in length, where the power injected into the plasma is 200W. The structure of the measured electron energy probability function (EEPF) can be approximated as a Druyvesteyn-like distribution at any N$_2$ content. The electron density, which is on the order of 10$^{16} $-10$^{17}$(m$^{-3}$), increases with increasing the Ar content, whereas the effective electron temperature slightly decreases. The vibrational and rotational temperatures can be estimated from the optical emission spectroscopy of N$_2$ second positive system. The vibrational temperature is higher than 10000K at any experimental condition, and the rotational temperature monotonically increases from 500K to 1000K with the increase in the Ar content. Moreover, the N$_2$ dissociation rate, which corresponds to the density ratio of N to N$_2$, can be estimated by actinometry. The dissociation rate reaches the maximum when the Ar content is about 85$\%$.