Probe Measurements and Optical Emission Spectroscopy in Inductively Coupled Ar/CF₄, Ar/NF₃, and Ar/SF₆ Discharges

Abstract

Experiments of inductive Ar/CF 4 , Ar/NF 3 , and Ar/SF 6 discharges with a Langmuir probe and optical emission spectroscopy are carried out in the total pressure range of 8 -30 mTorr, changing the ratio of the partial pressure of reactive gas to the total pressure (the fraction of the reactive gas) from 0 to 30%. The structure of the measured electron energy probability functions (EEPFs) deviates from the Maxwellian distribution owing to the large depletion of high-energy electrons at any reactive gas fraction. The electron density markedly decreases with increasing reactive gas fraction in the fraction range below 10%, whereas the electron temperature gradually increases. The density of the ground state fluorine atoms in the Ar/SF 6 and Ar/ NF 3 discharges is about 5 times higher than that in the Ar/CF 4 discharges. The effects of oxygen addition on the plasma parameters in those discharges are also investigated. The plasma parameters, such as electron density and temperature, do not depend on the fraction of oxygen for the fixed fraction of Ar. On the other hand, the dependence of the fluorine atom density on the fraction of oxygen differs among the inductive Ar/CF 4 , Ar/NF 3 , and Ar/SF 6 discharges.

Application of Si and SiO2 Etching Mechanisms in CF4/C4F8/Ar Inductively Coupled Plasmas for Nanoscale Patterns

“…The results of numerous existing studies (for example, Refs. [4,6,[14][15][16][17][18][19][20][21][22][23]) allow the formulation of the main properties of these two systems, which are important for dry-etching applications: (1) Under the conditions of a low-pressure (p < 50 mTorr) gas discharge plasma, the densities of F atoms in pure CF 4 and C 4 F 8 gas systems are very similar. 24 At low input powers (W < 500 W), a slightly higher F atom density has been measured in the CF 4 plasma, whereas at high power (W > 1000 W), the opposite occurs.…”

Optical Diagnostics of SF6 Low Pressure Plasma Jet Applied to Silicon Etching

“…We can infer that a remarkable increase (about 3 times) of n F must occur in the transition plasma, a phenomenon that deserves further investigation. We highlight the highest measured concentrations of fluorine atoms in the plasma jet, around 12%, a value comparable with ICP systems when operated at similar conditions (13).…”

Gain and loss mechanisms for neutral species in low pressure fluorocarbon plasmas by infrared spectroscopy

“…The correction factor, C F , Ar , related to the relative excitation cross sections, has been previously estimated 39 to be 0.6. The argon density was calculated from the flow rate and the residence time, assuming room temperature.…”