Experiments with a Langmuir probe and optical emission spectroscopy combined with actinometry are carried out in inductively coupled rf (13.56 MHz) Ar/H2 discharges at total pressures of 20 m, 40 m, and 60 mTorr in hydrogen fractions ranging from 0% to 50%. The measured electron energy probability functions (EEPFs), which deviate from the Maxwellian distributions owing to the depletion of high-energy electrons, can be approximated using two temperatures. The electron temperatures, which can be deduced from the slopes of low-energy and high-energy parts of the EEPFs, relatively abruptly increase with increasing the hydrogen fraction in the hydrogen fractions below 10%, whereas the measured electron density markedly decreases with increasing the hydrogen fraction in the hydrogen fractions below 20%. The effective ion mass, which can be estimated from the ion current collected into the probe, markedly decreases with increasing the hydrogen fraction. The density of hydrogen atoms estimated by actinometry markedly increases as molecular hydrogen is added to Ar discharges, and then gradually increases with increasing the hydrogen fraction at the hydrogen fractions higher than 10%–20%. A global model is used to study the effect of Ar dilution to hydrogen discharges on the plasma parameters assuming the Maxwellian electron energy distribution. The model results are compared with the experimental results, obtaining reasonably good agreement.

Experiments with a Langmuir probe and optical emission spectroscopy are carried out in inductively coupled rf ͑13.56 MHz͒ Ar/ N 2 discharges at three total pressures of 30, 60, and 110 mTorr, varying the Ar fractions from 50% to 95%. The electron energy probability functions ͑EEPFs͒ measured at all Ar fractions can be approximated using different exponentials in the bulk and high-energy regions, resulting in two temperature approximation of the measured EEPFs. The electron density slightly increases with increasing the Ar fraction at the Ar fractions below 70%, beyond which it relatively abruptly increases. On the other hand, the electron temperatures gradually decrease with the increase in the Ar fraction. The vibrational temperature does not strongly depend on the Ar fraction, whereas the rotational temperature gradually increases with the increase in the Ar fraction. The density of nitrogen atoms remains constant at the Ar fractions below 80%, beyond which it monotonically decreases with increasing the Ar fraction. A global model for electropositive plasma is used in order to investigate the plasma chemistry in Ar/ N 2 discharges assuming the Maxwellian electron energy distribution. The model results are compared with the experimental results, obtaining reasonably good agreement.

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Experiments with a Langmuir probe and optical emission spectroscopy combined with actinometry are carried out in inductively coupled rf (13.56 MHz) CH4/H2 plasmas at three total pressures of 25, 50, and 100 mTorr for hydrogen fractions ranging from 0 to 80%. The measured electron density gradually decreases with increasing hydrogen fraction, whereas the measured effective electron temperature slightly increases with hydrogen fraction. The density of hydrogen atoms estimated by actinometry does not strongly depend on hydrogen fraction. The high density of hydrogen molecules can be expected even in CH4 plasmas from the optical intensity emitted from the excited hydrogen molecules. A global model is analyzed in order to understand the plasma chemistry in CH4/H2 plasmas. In the model, the dominant neutral species are always hydrogen and CH4 molecules, followed by hydrogen atoms and hydrocarbons, such as C2H n (n=1, 2, and 4). On the other hand, the dominant ions are CH5 +, C2H+, C2H3 +, C2H5 +, and C3H5 + at low hydrogen fraction, whereas H3 + ions become dominant ion species as hydrogen fraction increases.

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