Electron dynamics during the reignition of pulsed capacitively-coupled radio-frequency discharges

Abstract

The authors report on phase resolved optical emission spectroscopy (PROES) measurements of pulsed capacitive coupled plasmas (CCPs) through argon. The PROES results indicate that under some conditions, the electron heating mechanism can be changed substantially from that dominant in continuous CCPs. The normally dominant α heating mode of electropositive plasmas can be aided by a drift-ambipolar (DA) heating mode during the early portion of the reignition. The DA heating mode is ordinarily only found in electronegative discharges. The authors found that Ar discharges pulsed at 10 kHz only exhibited the α heating mode throughout the reignition process, while those pulsed at 0.1 kHz exhibited a mixed α and DA heating mode during the reignition. The differences in the two heating modes cause substantial differences in the spatial pattern of the light emission from the plasma in addition to an overshoot in the light emission intensity.

Self-consistent simulation of the impedance matching network for single frequency capacitively coupled plasma

“…Indeed, for SF CCP, simplified CCP models already provide a good estimate of the nominal inductor and capacitor values needed, and the variable capacitors anyway have a range of values that allows the user to compensate for any differences compared with theory or any non-ideal effects. However, for some more complex cases like pulsed CCP [17,18] and CCP driven by TVWs [19][20][21][22][23], the design of matching circuit based on these simplified CCP models is hard or even impossible, due to the complexity and non-linearity. Our model thus may provide a feasible solution to these more complicated cases.…”

“…Furthermore, design of the matching networks is one of the key issues in some new CCP configurations, to achieve better control over specific plasma characteristics. Recent efforts include dual-frequency CCP [9,[13][14][15][16], pulsed CCP [17,18] and CCP driven by tailored voltage waveforms (TVWs) [19][20][21][22][23] used in etching at low pressure, as well as CCP at atmosphere [24], or even using CCP as a tunable impedance element for RF systems [25].…”

Science-based, data-driven developments in plasma processing for material synthesis and device-integration technologies

“…Lower frequency is exhibited in a mixture of the α heating mode and driftambipolar heating mode, which is ordinarily only found in electronegative discharges. 62) Electrical characteristics, such as RF current and voltage, power, and direct current (DC) bias voltage, were measured as a function of time during the reignition of pulsed Ar plasmas. The overshoot at reignition reflected the moving heating mechanisms, from stochastic heating to a combination of stochastic and ohmic heating.…”

Fundamental study towards a better understanding of low pressure radio-frequency plasmas for industrial applications

“…This process features a fast change of the electrical parameters, as well as the electron power absorption mode. [13,87,[101][102][103][104][105] As the pulse ignition is a non-equilibrium process, high-resolution timedependent diagnostics are indispensable for the determination of the dynamic evolution of plasma parameters. [79,106,107] Gao et al [108] measured the temporal evolution of the input power and the electron density in a pulse-modulated ICP in argon, and examined the effects of the RF power and gas pressure.…”

“…Previous studies on the ignition process of a pulse modulated CCP mostly focused on the time evolution of the axially resolved or even spatially averaged plasma parameters (e.g., the plasma emission, the electron density and temperature, etc. ), [104,105,[109][110][111][112][113][114] however, a 300 mm-diameter electrode is used in current semiconductor industries and, therefore, time evolution of various plasma parameters is highly radius-dependent during the ignition process in a pulse modulated plasma. Su et al [115] studied, for the first time, the time evolution of discharge parameters at different radial positions over a 300 mm-diameter electrode during the ignition process of a pulse modulated CCP in argon by multi-fold experimental diagnostics.…”