An electrical plasma diagnostic method is proposed to determine plasma density and electron temperature. When two square voltages with different amplitudes are applied to a probe tip, a capacitor connected to the probe is charged due to the current flowing from the plasma. To obtain the plasma parameters, a circuit model with a nonlinear sheath and capacitor is proposed. The electron temperature and plasma density given by the model can be obtained from the ratio of the capacitor voltages. The results are in agreement with those obtained from electron energy probability functions in argon inductively coupled plasma discharge.

A wafer-type monitoring apparatus that can simultaneously measure the two-dimensional (2D) distributions of substrate temperature and plasma parameters is developed. To measure the temperature of the substrate, a platinum resistance temperature detector is used. The plasma density and electron temperature are obtained using the floating harmonics method, and incoming heat fluxes from the plasma to the substrate are obtained from the plasma density and electron temperature. In this paper, 2D distributions of the substrate temperature, plasma density, and electron temperature are obtained simultaneously for the first time in inductively coupled plasma. The shapes of the 2D distributions of the substrate temperature and incoming heat flux are similar to each other, but some differences are found. To understand that, an energy balance equation for the substrate is established, which shows good agreement with the experimental results. This apparatus will promote the understanding of surface reactions, which are very sensitive to the temperatures and plasma densities in plasma processing.

The effect of low-frequency power and high-frequency power on the electron energy probability function (EEPF) and the physical and electrical characteristics of plasma are experimentally investigated in a dual-frequency capacitively coupled plasma. RF powers of 2 MHz (low-frequency) and 13.56 MHz (high-frequency) are simultaneously applied to an electrode. EEPFs and DC self-bias voltages (V DC) are measured as one of the two RF powers is increased while the other is fixed. When the 2 MHz power increases at a fixed 13.56 MHz power, the electron density decreases, and the electron temperature increases with the decrease in the population of low-energy (below 5 V) electrons in the EEPF. Note that the increase in the low-frequency power is accompanied by a large decrease in V DC, which is related to the ion energy. On the other hand, when 13.56 MHz power increases at a fixed 2 MHz power, the electron density and the electron temperature significantly increase with the increase in the population of high-energy (above 5 V) electrons in the EEPF, while V DC decreases slightly. Experimental results show that the increase in the low-frequency power enhances the ion energy, and the increase in the high-frequency power enhances electron heating and ionization efficiency.

The purpose of the present study is

Total energy loss per ion–electron pair lost (εT) is investigated to optimize the plasma generation at various RF powers and gas pressures in an argon inductively coupled plasma (ICP). The ion densities and electron temperatures are measured to obtain εT at the plasma–sheath edge. At a fixed RF power, the obtained εT has a minimum at a certain electron temperature, and at this condition, an optimal plasma generation is achieved according to a global model. Since the electron temperature is a function of the gas pressure, at that certain gas pressure the energy loss in the plasma is minimized and plasma is generated most efficiently. Interestingly, the electron temperature at which εT becomes the minimum decreases as the RF power increases. This is explained by multistep ionization and the electron density dependence of the density of the excited states. Measured εT is compared with the calculated result from the global model that includes multistep ionization, and these are consistent with each other.