Measurement of plasma parameters in an inductively coupled plasma reactor

The objective is to deepen the understanding of basic plasma properties in a high-density inductively coupled plasma (ICP) reactor. The experiment using a Langmuir probe, which is made of tungsten wire having length of 2.3 mm and diameter of 0.65 mm, is carried out to determine the characteristics of argon plasma. The axial and radial distributions of the plasma density, electron temperature, and plasma potential are measured. It was found that the electron density is in the range of 1.0×1010 to 1.0×1011 cm−3, electron temperature 4∼6 eV, and plasma potential 35∼45 V, respectively. These plasma parameters are spatially nonuniform in the axial direction; they depend on the distance between the plasma source and the measuring point. Next, etching of polycristalline silicon wafer by chlorine plasma is studied. The results obtained in this study indicate the effects of rf coil power, gas pressure, and substrate rf bias power on the distributions of the etch rate.