Self Bias of an R.F. Driven Probe in an R.F. Plasma

1988 ◽  
Vol 117 ◽  
Author(s):  
N M P Benjamin ◽  
N St J Braithwaite ◽  
J E Allen
Keyword(s):  
Bias Voltage ◽  
Langmuir Probe ◽  
Bessel Functions ◽  
The Self ◽  
Potential Difference ◽  
General Interest ◽  
Modified Bessel Functions ◽  
Self Bias ◽  
Compensation Signal ◽  
Good Agreement

AbstractAn effect of sinusoidal r.f. voltages between a plasma and a floating Langmuir probe (or other electrode) is to produce a d.c. self bias voltage. This effect has previously been studied with r.f. applied to probes in d.c. plasmas, and the results have often been referred to in connection with d.c. probes in r.f. plasmas, although the situation is slightly different. In the current work a ‘d.c.’ probe in an r.f. plasma is examined. However, the r.f. potential difference between probe and plasma is first compensated for by superimposing a synchronous signal of appropriate amplitude and phase on to the d.c. circuit. Thus the probe can perform essentially d.c. type measurements on the r.f. plasma. The deliberate reintroduction of a measure of r.f. between probe and plasma is accomplished by overdriving the compensation signal thereby generating a controlled amount of self bias.The observed variation of probe bias with r.f. overdrive is in good agreement with analytic theory based upon modified Bessel functions as used for d.c. generated plasmas. This work is of general interest in probe diagnostics of r.f. generated plasmas, and understanding the self bias of isolated electrodes.

scholarly journals Redefinition of the self-bias voltage in a dielectrically shielded thin sheath RF discharge

2018 ◽  
Vol 123 (19) ◽  
pp. 193301 ◽  
Author(s):  
Teck Seng Ho ◽  
Christine Charles ◽  
Rod Boswell
Keyword(s):  
Bias Voltage ◽  
The Self ◽  
Rf Discharge ◽  
Self Bias

Ion flux's pressure dependence in an asymmetric capacitively coupled rf discharge in NF3

Open Physics ◽  
2004 ◽  
Vol 2 (1) ◽  
pp. 1-11 ◽  
Author(s):  
Emil Mateev ◽  
Ivan Zhelyazkov
Keyword(s):  
Bias Voltage ◽  
Essential Feature ◽  
Gas Pressure ◽  
Ion Flux ◽  
The Self ◽  
Rf Discharge ◽  
Rf Power ◽  
Capacitively Coupled ◽  
Self Bias ◽  
Basic Equations

AbstractStarting from an analytical macroscopic/phenomenological model yielding the self-bias voltage as a function of the absorbed radio-frequency (rf) power of an asymmetric capacitively coupled discharge in NF3 this paper studies the dependence of the ion flux onto the powered electrode on the gas pressure. An essential feature of the model is the assumption that the ions' drift velocity in the sheath near the powered electrode is proportional to E α, where E=−ΔU (U being the self-bias potential), and α is a coefficient depending on the gas pressure and cross section of elastic ion-neutral collisions. The model also considers the role of γ-electrons, stochastic heating as well as the contribution of the active electron current to the global discharge power balance. Numerically solving the model's basic equations one can extract the magnitude of the ion flux (at three different gas pressures) in a technological etching device (Alcatel GIR 220) by using easily measurable quantities, notably the self-bias voltage and absorbed rf power.

scholarly journals Study of Power Balance in Electronegative Capacitively Coupled Plasmas

2004 ◽  
Vol 1 (2) ◽  
pp. 5-12
Author(s):  
Laura Swart ◽  
Patrick Verdonck ◽  
Stanislav A. Moshkalev
Keyword(s):  
Bias Voltage ◽  
Average Energy ◽  
Plasma Potential ◽  
Original Model ◽  
Ion Flux ◽  
Plasma Sheath ◽  
The Self ◽  
Total Power ◽  
Self Bias ◽  
Plasma Bulk

The balance of power model is a relatively simple model, which determines the power dissipated both in the plasma bulk and in the plasma sheath, as well as the ion flux and the average energy lost by an electron in the plasma bulk. It requires only the measurement of the total power and the self bias voltage. The original model does not take into account the effect of the plasma potential on the energy of incoming ions, because for most plasmas, the plasma potential is negligible compared with the self bias voltage. In this work, the plasma potential was taken into account. For pure SF6 plasmas, the modification had a significant effect on the ion flux, which increased by more than a factor 2, when compared with the original model. Besides, there are strong indications that the silicon etching with SF6 was mostly determined by the plasma bulk power, but the contribution from ion bombardment was considerable, too. For less electronegative plasmas, the influence of the plasma potential may be neglected.

Energy losses due to vortex shedding from the lower edge of a vertical plate attacked by surface waves

1984 ◽  
Vol 396 (1810) ◽  
pp. 131-142 ◽  
Keyword(s):  
Vortex Shedding ◽  
Bessel Functions ◽  
Vertical Plate ◽  
Generation Process ◽  
Vortex Generation ◽  
Modified Bessel Functions ◽  
Incoming Wave ◽  
Dimensional Parameters ◽  
Wave Energy Flux ◽  
Good Agreement

The ratio between the flux of the energy taken out by the vortex generation process e v , and the incoming wave energy flux e w , is shown to be given by e v / e w ≈ 2 α ⅔ /{ μ [ K 2 1 ( μ ) + π 2 I 2 1 ( μ )]} 4 / 3 , where α = νr 0 and μ = νT are non-dimensional parameters and K 1 , I 1 are modified Bessel functions. The parameters r 0 and ν are the amplitude and wavenumber of the incoming wave, respectively, and T is the draught of the plate. This theoretically derived formula is in good agreement with experimental evidence.

Asymptotic expansions and converging factors V. Lommel, Struve, modified Struve, Anger and Weber functions, and integrals of ordinary and modified Bessel functions

1959 ◽  
Vol 249 (1257) ◽  
pp. 284-292 ◽  
Keyword(s):  
Asymptotic Expansions ◽  
Bessel Functions ◽  
Modified Bessel Functions ◽  
Lommel Functions ◽  
Special Cases

A theory of Lommel functions is developed, based upon the methods described in the first four papers (I to IV) of this series for replacing the divergent parts of asymptotic expansions by easily calculable series involving one or other of the four ‘basic converging factors’ which were investigated and tabulated in I. This theory is then illustrated by application to the special cases of Struve, modified Struve, Anger and Weber functions, and integrals of ordinary and modified Bessel functions.

scholarly journals Characterization and Performance of Carbon Films Deposited by Plasma and Ion Beam Based Techniques

1994 ◽  
Vol 354 ◽  
Author(s):  
K.C. Walter ◽  
H. Kung ◽  
T. Levine ◽  
J.T. Tesmer ◽  
P. Kodali ◽  
...  
Keyword(s):  
Wear Rate ◽  
Surface Area ◽  
Ion Beam ◽  
Carbon Films ◽  
The Self ◽  
Line Of Sight ◽  
Rf Power ◽  
Hard Carbon ◽  
Self Bias ◽  
Cathodic Arc

AbstractPlasma and ion beam based techniques have been used to deposit carbon-based films. The ion beam based method, a cathodic arc process, used a magnetically mass analyzed beam and is inherently a line-of-sight process. Two hydrocarbon plasma-based, non-line-of-sight techniques were also used and have the advantage of being capable of coating complicated geometries. The self-bias technique can produce hard carbon films, but is dependent on rf power and the surface area of the target. The pulsed-bias technique can also produce hard carbon films but has the additional advantage of being independent of rf power and target surface area. Tribological results indicated the coefficient of friction is nearly the same for carbon films from each deposition process, but the wear rate of the cathodic arc film was five times less than for the self-bias or pulsed-bias films. Although the cathodic arc film was the hardest, contained the highest fraction of sp3 bonds and exhibited the lowest wear rate, the cathodic arc film also produced the highest wear on the 440C stainless steel counterface during tribological testing. Thus, for tribological applications requiring low wear rates for both counterfaces, coating one surface with a very hard, wear resistant film may detrimentally affect the tribological behavior of the counterface.

Sign in / Sign up

Export Citation Format

Share Document