Time-resolved electrostatic probe studies of a pulsed inductively-coupled plasma

Tang, Xianmin; Manos, D. M.

doi:10.1088/0963-0252/8/4/311

Cited by 22 publications

(16 citation statements)

References 61 publications

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“…This sudden change introduces electromagnetic effects that result in an observed spike during transition. 25 Another reason may be the limitation of probe theory. As the discharge undergoes transition from the pulse on-time to pulse off-time, the ratio of the probe radius to the sheath thickness (r p /k D ) changes, restricting the particular probe theory for both cases.…”

Section: Resultsmentioning

confidence: 99%

“…Further complication then arises due to the sheath displacement current. 25,26 This sheath displacement current should be subtracted from the ion-saturation current for the decay period in order to obtain better approximated values.…”

Section: Resultsmentioning

confidence: 99%

“…5. A high electron temperature T e is observed ($30 eV) at the beginning of the RF pulse and it is caused by electron heating due to the capacitive electric fields in the low-density plasma 25 and partly due to the strong RF incursion on the I-V characteristics during the transition period. Moving into the pulse, at $35 ls after the initiation of the 2 MHz pulse, the electron temperature rapidly decreases and this trend continues up to $100 ls, when the T e becomes $8 eV.…”

Section: Resultsmentioning

confidence: 99%

“…This agrees with the stabilization characteristic time in the creation process of the plasma in the magnitude of hundreds of microseconds. 25 A comparison of Figs. 3 and 5 shows that the electron density (n e ) almost linearly increases up to $250 ls.…”

Section: Resultsmentioning

confidence: 99%

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Plasma dynamics in a discharge produced by a pulsed dual frequency inductively coupled plasma source

Mishra

Lee

Yeom

2014

Journal of Vacuum Science &Amp; Technology A: Vacuum, Surfaces, and Films

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Using a Langmuir probe, time resolved measurements of plasma parameters were carried out in a discharge produced by a pulsed dual frequency inductively coupled plasma source. The discharge was sustained in an argon gas environment at a pressure of 10 mTorr. The low frequency (P2 MHz) was pulsed at 1 kHz and a duty ratio of 50%, while high frequency (P13.56 MHz) was maintained in the CW mode. All measurements were carried out at the center of the discharge and 20 mm above the substrate. The results show that, at a particular condition (P2 MHz = 200 W and P13.56 MHz = 600 W), plasma density increases with time and stabilizes at up to ∼200 μs after the initiation of P2 MHz pulse at a plasma density of (2 × 1017 m−3) for the remaining duration of pulse “on.” This stabilization time for plasma density increases with increasing P2 MHz and becomes ∼300 μs when P2 MHz is 600 W; however, the growth rate of plasma density is almost independent of P2 MHz. Interestingly, the plasma density sharply increases as the pulse is switched off and reaches a peak value in ∼10 μs, then decreases for the remaining pulse “off-time.” This phenomenon is thought to be due to the sheath modulation during the transition from “pulse on” to “pulse off” and partly due to RF noise during the transition period. The magnitude of peak plasma density in off time increases with increasing P2 MHz. The plasma potential and electron temperature decrease as the pulse develops and shows similar behavior to that of the plasma density when the pulse is switched off.

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Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

See 2 more Smart Citations

Plasma dynamics in a discharge produced by a pulsed dual frequency inductively coupled plasma source

Mishra

Lee

Yeom

2014

Journal of Vacuum Science &Amp; Technology A: Vacuum, Surfaces, and Films

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“…58 This is especially true for the off phase when the probe sheath expands so much that n i is overestimated according to Ref. 45.…”

Section: -6mentioning

confidence: 99%

Plasma parameters of pulsed-dc discharges in methane used to deposit diamondlike carbon films

Corbella

Rubio‐Roy

Bertrán

et al. 2009

Journal of Applied Physics

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Here we approximate the plasma kinetics responsible for diamondlike carbon ͑DLC͒ depositions that result from pulsed-dc discharges. The DLC films were deposited at room temperature by plasma-enhanced chemical vapor deposition ͑PECVD͒ in a methane ͑CH 4 ͒ atmosphere at 10 Pa. We compared the plasma characteristics of asymmetric bipolar pulsed-dc discharges at 100 kHz to those produced by a radio frequency ͑rf͒ source. The electrical discharges were monitored by a computer-controlled Langmuir probe operating in time-resolved mode. The acquisition system provided the intensity-voltage ͑I-V͒ characteristics with a time resolution of 1 s. This facilitated the discussion of the variation in plasma parameters within a pulse cycle as a function of the pulse waveform and the peak voltage. The electron distribution was clearly divided into high-and low-energy Maxwellian populations of electrons ͑a bi-Maxwellian population͒ at the beginning of the negative voltage region of the pulse. We ascribe this to intense stochastic heating due to the rapid advancing of the sheath edge. The hot population had an electron temperature T e hot of over 10 eV and an initial low density n e hot which decreased to zero. Cold electrons of temperature T e cold ϳ 1 eV represented the majority of each discharge. The density of cold electrons n e cold showed a monotonic increase over time within the negative pulse, peaking at almost 7 ϫ 10 10 cm −3 , corresponding to the cooling of the hot electrons. The plasma potential V p of ϳ30 V underwent a smooth increase during the pulse and fell at the end of the negative region. Different rates of CH 4 conversion were calculated from the DLC deposition rate. These were explained in terms of the specific activation energy E a and the conversion factor x dep associated with the plasma processes. The work deepens our understanding of the advantages of using pulsed power supplies for the PECVD of hard metallic and protective coatings for industrial applications ͑optics, biomedicine, and electronics͒.

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Measuring the ion current in high-density plasmas using radio-frequency current and voltage measurements

Sobolewski

2001

Journal of Applied Physics

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The total current or flux of ions striking the substrate is an important parameter that must be tightly controlled during plasma processing. Several methods have recently been proposed for monitoring the ion current in situ. These methods rely on passive, noninvasive measurements of the radio frequency (rf) current and voltage signals that are generated by plasma-processing equipment. The rf measurements are then interpreted by electrical models of the plasma discharge. Here, a rigorous and comprehensive test of such methods was performed for high-density discharges in argon at 1.33 Pa (10 mTorr) in an inductively coupled plasma reactor, at inductive source powers of 60–350 W, rf bias powers up to 150 W, and rf bias frequencies of 0.1–10 MHz. Model-based methods were tested by comparison to direct, independent measurements of the ion current at the substrate electrode made using lower frequency (10 kHz) rf bias and modulated rf bias. Errors in two model-based methods are identified and explained by effects that are present in the high-density plasmas but are not included in the models. A third method, based on a new, more accurate numerical sheath model, gives values of the ion current in agreement with the independent measurements.

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Time-resolved electrostatic probe studies of a pulsed inductively-coupled plasma

Cited by 22 publications

References 61 publications

Plasma dynamics in a discharge produced by a pulsed dual frequency inductively coupled plasma source

Plasma dynamics in a discharge produced by a pulsed dual frequency inductively coupled plasma source

Plasma parameters of pulsed-dc discharges in methane used to deposit diamondlike carbon films

Measuring the ion current in high-density plasmas using radio-frequency current and voltage measurements

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