Electron heating and control of electron energy distribution for the enhancement of the plasma ashing processing

Lee, Hyo-Chang; Chung, Chin-Wook

doi:10.1088/0963-0252/24/2/024001

Cited by 17 publications

(7 citation statements)

References 49 publications

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“…The evolution in T e is interesting because it was well known that T e will either remain constant or slightly decrease with n e in the single-step or multi-step ionization global model. 1, 16 One possible explanation for this trend in T e may be the dramatic evolution of the EEPF through the electron heating effect 11,21,[30][31][32][33][34][35][36][37] or electronelectron collisions. 17,26,38,39 However, our experiment was conducted in plasmas having nearly Maxwellian EEPFs.…”

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confidence: 99%

Evolution of electron temperature in inductively coupled plasma

Lee

Seo

Kwon

et al. 2017

Applied Physics Letters

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It is generally recognized that the electron temperature Te either remains constant or decreases slightly with plasma power (plasma density). This trend can be simply verified using a single-step or multi-step fluid global model. In this work, however, we experimentally observed that Te evolved with plasma power in radio frequency (RF) inductively coupled plasmas. In this experiment, the measured electron energy distributions were nearly Maxwellian distribution. In the low RF power regime, Te decreased with increasing plasma power, while it increased with plasma power in the high RF power regime. This evolution of Te could be understood by considering the coupling effect between neutral gas heating and stepwise ionization. Measurement of gas temperature via laser Rayleigh scattering and calculation of Te using the kinetic model, considering both multi-step ionization and gas heating, were in good agreement with the measured value of Te. This result shows that Te is in a stronger dependence on the plasma power.

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confidence: 99%

Evolution of electron temperature in inductively coupled plasma

Lee

Seo

Kwon

et al. 2017

Applied Physics Letters

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“…[1][2][3][4][5] Plasma technology is also becoming more important for biomedical applications such as sterilization and wound healing. [6][7][8] For many of these applications capacitively coupled radio frequency (CCRF) discharges or hybrid combinations of CCRF plasmas with high density remote sources represent the most important reactor types, [9][10][11] since such plasmas allow for an efficient processing of dielectric substrates based on high fluxes of ions and chemically reactive radicals. In particular, the mean ion energy at the electrodes, which is crucially important for the plasma surface interaction, can be controlled in this type of plasmas.…”

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confidence: 99%

Experimental investigations of electron heating dynamics and ion energy distributions in capacitive discharges driven by customized voltage waveforms

Berger

Brandt

Franek

et al. 2015

Journal of Applied Physics

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Capacitively coupled radio frequency plasmas driven by customized voltage waveforms provide enhanced opportunities to control process-relevant energy distributions of different particle species. Here, we present an experimental investigation of the spatio-temporal electron heating dynamics probed by Phase-Resolved Optical Emission Spectroscopy (PROES) in an argon discharge driven by up to three consecutive harmonics of 13.56 MHz with individually adjustable harmonics' amplitudes and phases. PROES and voltage measurements are performed at fixed total voltage amplitudes as a function of the number of driving harmonics, their relative phases, and pressure to study the effects of changing the applied voltage waveform on the heating dynamics in collisionless and collisional regimes. Additionally, the ion energy distribution function (IEDF) is measured at low pressure. In this collisionless regime, the discharge is operated in the a-mode. The velocity of energetic electron beams generated by the expanding sheaths is found to be affected by the number of driving harmonics and their relative phases. This is understood based on the sheath dynamics obtained from a model that determines sheath voltage waveforms. The formation of the measured IEDFs is understood and found to be directly affected by the observed changes in the electron heating dynamics. It is demonstrated that the mean ion energy can be controlled by adjusting the harmonics' phases. In the collisional regime at higher pressures changing the number of harmonics and their phases at fixed voltage is found to induce heating mode transitions from the ato the c-mode. Finally, a method to use PROES as a non-invasive diagnostic to monitor and detect changes of the ion flux to the electrodes is developed. V C 2015 AIP Publishing LLC.

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“…Composed of physically energetic charged particles and chemically reactive neutral particles, plasma has been widely used in various fields including material fabrication and nuclear fusion as well as medical, environmental, and aerospace industries [ 1 , 2 ]. Plasma processing techniques such as plasma etching [ 3 , 4 , 5 , 6 , 7 ], ashing [ 8 , 9 , 10 , 11 ], and deposition [ 12 , 13 , 14 , 15 , 16 ] are the most important steps to fabricate the high-end memory and system semiconductors used in internet of things and artificial intelligence technologies. For plasma deposition in particular, plasma sputtering, plasma-enhanced chemical vapor deposition (PECVD), and plasma-enhanced atomic layer deposition (PEALD) approaches have been widely used for their high deposition rates, low-temperature processing, good film conformality, and high film uniformity [ 12 , 13 , 17 , 18 ].…”

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confidence: 99%

Crossing Frequency Method Applicable to Intermediate Pressure Plasma Diagnostics Using the Cutoff Probe

Kim¹,

Lee

et al. 2022

Sensors

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Although the recently developed cutoff probe is a promising tool to precisely infer plasma electron density by measuring the cutoff frequency (fcutoff) in the S21 spectrum, it is currently only applicable to low-pressure plasma diagnostics below several torr. To improve the cutoff probe, this paper proposes a novel method to measure the crossing frequency (fcross), which is applicable to high-pressure plasma diagnostics where the conventional fcutoff method does not operate. Here, fcross is the frequency where the S21 spectra in vacuum and plasma conditions cross each other. This paper demonstrates the fcross method through three-dimensional electromagnetic wave simulation as well as experiments in a capacitively coupled plasma source. Results demonstrate that the method operates well at high pressure (several tens of torr) as well as low pressure. In addition, through circuit model analysis, a method to estimate electron density from fcross is discussed. It is believed that the proposed method expands the operating range of the cutoff probe and thus contributes to its further development.

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Electron heating and control of electron energy distribution for the enhancement of the plasma ashing processing

Cited by 17 publications

References 49 publications

Evolution of electron temperature in inductively coupled plasma

Evolution of electron temperature in inductively coupled plasma

Experimental investigations of electron heating dynamics and ion energy distributions in capacitive discharges driven by customized voltage waveforms

Crossing Frequency Method Applicable to Intermediate Pressure Plasma Diagnostics Using the Cutoff Probe

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