Time-resolved curling-probe measurements of electron density in high frequency pulsed DC discharges

Self Cite

A microwave resonator probe called a curling probe (CP) was applied to in situ monitoring of a dielectric layer deposited on a chamber wall during plasma processing. The resonance frequency of the CP was analytically found to shift in proportion to the dielectric layer thickness; the proportionality constant was determined from a comparison with the finite-difference time-domain (FDTD) simulation result. Amorphous carbon layers deposited in acetylene inductively coupled plasma (ICP) discharge were monitored using the CP. The measured resonance frequency shift dictated the carbon layer thickness, which agreed with the results from the surface profiler and ellipsometry.

Section: Introductionmentioning

confidence: 99%

Real-time curling probe monitoring of dielectric layer deposited on plasma chamber wall

Hotta

Ogawa

Nakamura

et al. 2018

Self Cite

“…To achieve a high time resolution, the network analyzer used for the SW probe measurement was operated in the on-point mode synchronized with the pulse period. 22) As a result, the time-varying electron density was measured with a resolution of 0.1 µs.…”

mentioning

confidence: 99%

Rapid electron density decay observed by surface-wave probe in afterglow of pulsed fluorocarbon-based plasma

Ohya

Iwata

Ishikawa

et al. 2016

Self Cite

To elucidate the pulsed fluorocarbon plasma behavior, a surface-wave probe with high time resolution was used to measure the electron density n e in the afterglow of plasma. In a dual-frequency capacitively coupled plasma of fluorocarbon chemistry, e.g., an O2-based C4F6 and Ar mixture, n e vanished rapidly in a short time (∼5 µs), whilst the dc current flowing onto the top electrode biased at −300 V decreased very slowly (decay time ∼70 µs). This observation is clear evidence of ion–ion plasma formation by electron attachment in the afterglow. We point out that the electron attachment rates for fluorocarbon radicals significantly affect the electrons and ion–ion plasma behaviors observed at the afterglow phase.

“…The Γ spectra were measured using the network analyzer on-point mode at the desired phase of each discharge pulse and synchronizing with the phase of the pulse operation of plasma discharges. 33) The optical emission was collected by a lens through a quartz window equipped at the side of the etcher. The lens focused above the center of the bottom electrode with a 300 mm wafer.…”

Section: Experimental Methodsmentioning

confidence: 99%

Electron behaviors in afterglow of synchronized dc-imposed pulsed fluorocarbon-based plasmas

Ueyama

Fukunaga

Tsutsumi

et al. 2017

Self Cite

Electron behaviors in a pulsed dual radio frequency (RF) capacitively coupled plasma of a mixture of C 4 F 8 , O 2 , and Ar gases, where the DC bias of %300 V in the RF-on period was imposed and synchronously increased to %1000 V in the RF-off period, were investigated. The synchronous DC bias prolongs the electron density (n e ) decay and provides emission of Ar at a wavelength of 750.38 nm in early afterglow at 3 µs during the RF-off period of 10 kHz pulse modulation. The rapid n e decay occurred with the electron attachments to the electronegative fluorocarbons, and thus the plasma consisting of positive and negative ions was generated. The DC bias voltage seems to be applied between the electrodes and the positive ions accelerated to the top electrode, and enhanced the secondary electron generation at the top electrode surface in the RF-off period with the ion bombardments, concomitantly with the synchronous emissions.