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![Typical breakdown and time lag under impulse voltage. Here, V p and V s are peak voltage and minimum breakdown voltage, respectively, and t B and t v are the breakdown time and the time when the charge voltage exceeds V s , respectively. Moreover, τ, τ s , and τ f are the delay time, the statistical time, and formative time, respectively [36].](publication/351058051/figure/fig3/AS:1022520572530688@1620799310046/Typical-breakdown-and-time-lag-under-impulse-voltage-Here-V-p-and-V-s-are-peak-voltage.png)
Typical breakdown and time lag under impulse voltage. Here, V p and V s are peak voltage and minimum breakdown voltage, respectively, and t B and t v are the breakdown time and the time when the charge voltage exceeds V s , respectively. Moreover, τ, τ s , and τ f are the delay time, the statistical time, and formative time, respectively [36].
Source publication
Delayed discharges due to electrical breakdown are observed in modulated pulsed pow er magnetron sputtering (MPPMS) plasma of titanium. The delayed discharge, which is remarkable with decreasing argon gas pressure, transforms the discharge current waveform from a standard modulated pulsed discharge current waveform to a comb-like discharge current...
Contexts in source publication
Context 1
... delayed discharge originates from the electrical breakdown (ignition). The onset and voltage waveform of delayed discharges are shown in Figure 4 [36]. Whether electrical breakdown occurs and the degree of the time lag from the applied point of charging voltage are explained by Townsend's discharge theory formula. ...
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The magnetic field is a key feature that distinguishes magnetron sputtering from simple diode sputtering. It effectively increases the residence time of electrons close to the cathode surface and by that increases the energy efficiency of the discharge. This becomes apparent in high power impulse magnetron sputtering (HiPIMS) discharges, as small c...
Citations
... The experimental setup has been described in detail elsewhere. 27,31,32) The sputtering chamber was evacuated to a base pressure of 1 × 10 −5 Pa by a turbo molecular pump (Edwards, STP-A2203C). The DOMS was operated with Ar gas (99.999%) under a working pressure of 1.37 Pa. ...
... The first current pulse shown in Fig. 2(b) was observed to be roughly five times as strong as the other current pulses due to the strong electric breakdown voltage. However, in the second and subsequent discharges, the delayed discharge effect becomes weak due to the voltage not dropping to 0, 31) and the discharge current remains smaller than the first discharge. In the first pulse discharge, the maximum peak power was 25 kW and the peak power density was approximately 1.2 kW cm −2 . ...
Optical emission spectroscopic diagnostics is applied to determine the temporal evolution and distance dependence from the target surface for deep oscillation magnetron sputtering (DOMS) with a titanium target. In the time evolution of emission intensities for atomic lines of optically emitting species formed in DOMS plasma, the envelope of the peak emission intensity for sputtered neutrals in each pulsed discharge was observed to rise gradually with increasing distance. The increase in the distance dependence of the optical emission corresponds to plasma build-up from gas plasma to metallic plasma which has been reported in the deposition region using a time-of-flight mass spectrometer in J. Appl. Phys. 131, 243301 (2022). On the other hand, the ion confinement effect was strongly observed for sputtered ions in the region up to the edge of the magnetic trap around 40 mm downstream from the target surface for the first pulse discharge.
... 24 The delay time and/or the breakdown time, which are affected by the discharge voltage and discharge gas pressure, are important factors in discussing the discharge dynamics, which implies the process of pulse discharge generation and its stability. 22,25,26 In this figure, the time difference decreases rapidly with the number of pulses and reaches an approximately constant value at the fifth pulse and later. This time difference shows almost the same trend of the peak discharge current in the same figure. ...
... The pulse generator used in the present experiment has the property of producing a higher magnetron voltage depending on the delay time of the discharge. 26 Therefore, the ionization ratios of gas and sputtered metal particles should be higher in the first pulse due to the higher magnetron voltage. In each first pulse in Fig. 4, the Ar-ion peaks were observed with some intensity in the non-metallic plasma with rich Ar ions. ...
Reflectron-type time-of-flight mass spectrometry was applied to the time-resolved component analysis of deep oscillation magnetron sputtering (DOMS), which has been developed as a technique of modulated pulsed magnetron sputtering. In the present study, the DOMS of a Ti target was performed under an Ar gas atmosphere by using a DOMS-specific control waveform consisting of 25 current and/or power pulses. The time evolution of the formation of ionized species (Ar ⁺ , Ar ²⁺ , Ti ⁺ , and Ti ²⁺ ) after the application of the first discharge pulse was observed at the position corresponding to the deposition region. This study revealed that the plasma build-up process from non-metallic plasma to metallic plasma takes approximately two micropulses (around 100 μs from ignition) in DOMS discharge. In addition, we have found the possibility of studying sputtering processes, such as the rarefaction, and refilling processes of Ar as a function of pulse number through DOMS research.
... In the present study, the effect of the working gas pressure on the correlation between the discharge current/voltage and OES in MPPMS plasma was investigated to obtain further information on the optimal conditions for the formation of a deposited film using MPPMS. Comb-like discharge current waveforms [28] as used in DOMS, and strong optical emission of Ar + atomic lines which has not been reported in a pure metallic sputtering mode (, not in metal-oxide sputtering mode [29,30]) by MPPMS of a Ti target were observed as the gas pressure decreased. Furthermore, the optical emission intensities of sputtered Ti + ions and Ar + gas ions were also observed to change according to the number of pulses in the comb-like current waveforms. ...
... The grounded anode was a flat ring-shaped shield that was removed from the sputtering source in this study to observe the plasma emission closer to the target surface. The effect of the anode shape of the sputtering source on the discharge of the sputtering plasma was reported in detail in a previous paper [28], and it will not be further described here. ...
... The waveform of the micro pulse train is shown in Figure 2, which is used to control the insulated gate bipolar transistor (IGBT) in the pulse generator to chop the charging voltage. As detailed elsewhere [28], the pulse-on/-off time widths for the output waveform (macro pulse) were 6 µs/30 µs for the first pulse train and 12 µs/10 µs for the last pulse train. The bundle of micro pulses corresponds to the synchronous pulse, in which the rise and cut-off edges are formed by the first and the last micro pulses of the MPP system, respectively. ...
Modulated pulsed power magnetron sputtering (MPPMS) of titanium was investigated as a function of argon gas pressure using optical emission spectroscopy (OES). Delays in discharge and the formation of comb-like discharge current waveforms due to splitting and pulsing were observed with a decrease in pressure. This observation corresponds to the evolution from MPPMS condition to deep-oscillation-magnetron-sputtering (DOMS)-like condition by changing discharge gas pressure. The optical emission intensities of the ionic species (Ar+ and Ti+) increased as the comb-like current waveforms were formed with decreasing Ar pressure. This behavior showed a marked contrast to that of the neutral species (Ar and Ti). The Ar pressure dependence of OES was revealed to be due to the plasma build-up stage, which is the initial generation process of plasma discharge in pulsed dc magnetron sputtering, from the temporal profile for the atomic-line intensities of the optically emitting species in MPPMS and DOMS-like plasmas.
