Pressure and input power dependence of Ar/N2H2 inductively coupled plasma systems

Abstract

Pressure and input power dependence of inductively coupled plasma systems was investigated with the gas systems used for the chemical vapor deposition of metals and metal nitrides; H2, N2, Ar, and the H2/Ar and N2/H2 mixtures. The plasma density and the electron temperature were measured with a Langmuir single probe and the ionic species in the plasma were analyzed with a quadrupole mass spectrometer. The plasma density of Ar plasma measured 11 cm below the rf coil was in the 1017 m−3 range, which is about 1 order of magnitude higher than N2 plasma and 2 orders of magnitude higher than the H2 plasma. Capacitively coupled power transfer was observed for H2 and N2 plasmas when the plasma density was below about 2×1015 m−3. When the plasma density increased effectively with increasing pressure and input power while the electron temperature was independent of the input power. In the high pressure regime, the plasma density showed saturation in H2 and N2 plasmas and even decrease in N2 plasma. With an appropriate addition of Ar to the H2 plasma (H2/Ar plasma), the plasma density increased greatly and thus the production of atomic hydrogen was enhanced. In N2/H2 plasma, the plasma density changed little over a wide range of gas mixing ratio but the concentration of atomic nitrogen was decreased abruptly as the portion of H2 increased while the concentration of atomic hydrogen remained high even when the portion H2 was small.