Displacement current and multiple pulse effects in plasma source ion implantation

Wood, B.P.

doi:10.1063/1.353841

Cited by 75 publications

(29 citation statements)

References 12 publications

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“…It is indeed possible that the duty cycle is sufficiently high, hence, the sheath of successive pulses propagate in increasingly thinner plasma, and thus the sheath edge extents further from the surface with each pulse until equilibrium is reached between "pumping" of ions by the bias pulse and supply by the plasma. Such multiple-pulse effects have been modeled for plasma immersion ion implantation using a particle-cell-code [29] but the principle also applies to other pulsed systems like pulsed sputtering.…”

Section: Transient Sheathsmentioning

confidence: 99%

Fundamentals of pulsed plasmas for materials processing

Anders

2004

Surface and Coatings Technology

121

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Fundamentals of Pulsed Plasmas for Materials Processing André AndersLawrence Berkeley National Laboratory, University of California, 1 Cyclotron Road, Berkeley, California 94720-8223 AbstractPulsed plasmas offer the use of much higher power (during each pulse) compared to continuously operated plasmas, and additional new parameters appear such as pulse duty cycle. Pulsed processing may help meeting the demands of increasingly sophisticated materials processes, including thin film deposition, plasma etching, plasma cleaning of surfaces, and plasma immersion ion implantation. The high kinetic energy of ions allows processes to occur far from thermodynamic equilibrium. Pulsed plasmas are driven by external pulsed power sources, and one has to consider the power source and the plasma as a coupled system. The dynamic plasma impedance is a key quantity from an electrical engineering point of view.From a plasma physics point of view, one needs to consider the dynamics of plasma species, their density and energy distribution, ionization and recombination reactions, and, most importantly, the development of transient sheaths. Dimensionless scaling parameters are a useful tool putting the variety of plasma parameters in relation to characteristic quantities. This is illustrated by several examples of pulsed processes relevant to thin film deposition. The emerging technology of pulsed sputtering is discussed in detail including the possibility to achieve the mode of self-sustained self-sputtering during each pulse.3

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Section: Transient Sheathsmentioning

confidence: 99%

Fundamentals of pulsed plasmas for materials processing

Anders

2004

Surface and Coatings Technology

121

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“…Since ion transit time across the sheath is large (on the order of 1/X p ) and sheath expands during ion flight across the sheath, both the shape and magnitude of the potential barrier vary, so that the implanted ions do not get the full bias voltage. In other words, displacement current across the expanding sheath leads to an increase in the ion implanted current and causes a decrease in the implanted ion energy with respect to the stationary sheath with the same parameters [19,20]. According to Fig.…”

Section: Fluid Model and Basic Equationsmentioning

confidence: 99%

Influence of ion-neutral collision parameters on dynamic structure of magnetized sheath during plasma immersion ion implantation

Khoram

Ghomi

2016

J Theor Appl Phys

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A cold magnetized plasma sheath is considered to examine the gas pressure effect on the sheath dynamics. A fluid model is used to describe the plasma sheath dynamic. The governing fluid equations in the plasma are solved from plasma center to the target using the finite difference method and some convenient initial and boundary conditions at the plasma center and target. It is found that, the ion-neutral collision has significant effect on the dynamic characteristics of the high-voltage sheath in the plasma immersion ion implantation (PIII). It means that, the temporal profile of the ion dose on the target and sheath width are decreased by increasing the gas pressure. Also, the gas pressure substantially diminishes the temporal psychograph of ion incident angle on the target.

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“…Experimental study [11] have shown that large deviations in the retained dose could be observed in dependence on the sample geometry and plasma sheath thickness. Experiments for determining the dose distribution are very complicated so that various computer programs for simulating the implantation were developed [8]- [10], [12]- [17]. A self-consistent 3D calculation of the sheath dynamics and ion current is prohibitively time-consuming.…”

Section: Plasma Sheath Dynamicsmentioning

confidence: 99%

Two dimensional computer simulation of plasma immersion ion implantation

Kostov¹,

Barroso²,

Ueda³

2004

Braz. J. Phys.

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The biggest advantage of plasma immersion ion implantation (PIII) is the capability of treating objects with irregular geometry without complex manipulation of the target holder. The effectiveness of this approach relies on the uniformity of the incident ion dose. Unfortunately, perfect dose uniformity is usually difficult to achieve when treating samples of complex shape. The problems arise from the non-uniform plasma density and expansion of plasma sheath. A particle-in-cell computer simulation is used to study the time-dependent evolution of the plasma sheath surrounding two-dimensional objects during process of plasma immersion ion implantation. Before starting the implantation phase, steady-state nitrogen plasma is established inside the simulation volume by using ionization of gas precursor with primary electrons. The plasma self-consistently evolves to a non-uniform density distribution, which is used as initial density distribution for the implantation phase. As a result, we can obtain a more realistic description of the plasma sheath expansion and dynamics. Ion current density on the target, average impact energy, and trajectories of the implanted ions were calculated for three geometrical shapes. Large deviations from the uniform dose distribution have been observed for targets with irregular shapes. In addition, effect of secondary electron emission has been included in our simulation and no qualitative modifications to the sheath dynamics have been noticed. However, the energetic secondary electrons change drastically the plasma net balance and also pose significant X-ray hazard. Finally, an axial magnetic field has been added to the calculations and the possibility for magnetic insulation of secondary electrons has been proven.

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Displacement current and multiple pulse effects in plasma source ion implantation

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Cited by 75 publications

References 12 publications

Fundamentals of pulsed plasmas for materials processing

Fundamentals of pulsed plasmas for materials processing

Influence of ion-neutral collision parameters on dynamic structure of magnetized sheath during plasma immersion ion implantation

Two dimensional computer simulation of plasma immersion ion implantation

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