Decrease In Plasma Potential Research Articles

Characteristics of a dual‐radio‐frequency cylindrical inductively coupled plasma

The plasma parameters such as electron density, effective electron temperature, plasma potential, and uniformity are investigated in a new dual‐frequency cylindrical inductively coupled plasma (ICP) source operating at two frequencies (2 and 13.56 MHz) and two antennas (a two‐turn high‐frequency antenna and a six‐turn low‐frequency (LF) antenna). It is found that the electron density increases with 2 MHz power, whereas the electron temperature and plasma potential decrease with 2 MHz power at a fixed 13.56 MHz power. Moreover, the plasma uniformity can be improved by adjusting the LF power. These results indicate that a dual‐frequency synergistic discharge in a cylindrical ICP can produce a high‐density, low‐potential, low‐effective‐electron‐temperature, and uniform plasma.

Effect of electron emission on an ion sheath structure

This article reports on the variations of ion sheath structures due to the emission of both hot and cold electrons in the target plasma region of a double plasma device. The ion sheath is produced in front of a negatively biased plate. The plasma is produced by hot filament discharge in the source region, and no discharge is created in the target region of the device. The plate is placed in the target (diffused plasma) region where cold electron emitting filaments are present. These cold electrons are free from maintenance of discharge, which is sustained in the source region. The hot ionizing electrons are present in the source region. Three important parameters are changed by both hot and cold electrons i.e. plasma density, plasma potential and electron temperature. The decrease in plasma potential and the increase in plasma density lead to the contraction of the sheath.

Plasma Characteristics of Internal Inductively Coupled Plasma Source with Ferrite Module

Electrical and plasma properties of a U-shaped internal inductively coupled plasma (ICP) source with/without a Ni-Zn ferrite module installed above the ICP antenna were investigated. By installing the ferrite module on the antenna, the increase of plasma density and the decrease of plasma potential could be observed. The increase of plasma density was related to the efficient inductive coupling to the plasma by concentrating the induced magnetic field between the antenna and the substrate. At 800 W of ICP power and 20mTorr Ar, a high density plasma on the order of 4.5′1011/cm3 could be obtained.

Production of Inductively Coupled RF Plasma Using a Ladder-Shaped Antenna

A radio-frequency (RF) excited H2 plasma is produced using a ladder-shaped antenna which is positioned within a plasma chamber and the fundamental characteristics of the plasma are examined. The potential and current fed to the antenna are almost in phase. The plasma parameters are measured as a function of RF power, gas pressure and gas flow rate with a Langmuir probe. It is found that the plasma density is uniform within ±10% over 300 mm. Furthermore, increases in the frequency of the RF power source lead to increases in the plasma density. When a mesh grid is installed between the antenna and the substrate, the plasma density and the plasma potential decrease.

Langmuir probe measurements during plasma-activated chemical vapor deposition in the system argon/oxygen/Aluminum isopropoxide

A Langmuir probe investigation of Ar/O2/Al(OPr1)3 plasmas is described. The probe contamination depends on the probe position and the flow of tine carrier gases. Whereus far from the working gas inlet characteristics without any hysteresis were obtained, near to the inlet undisturbed characteristics were recorded only for small gas flows or a low vapor pressure of the precursor. Condensation of the precursor ai the probe surface prior to the plasma excitation was the main source of probe contamination. A decrease ire the plasma potential with respect to the ground observed during experiments was attributed to the formation of a dielectric film on the rf electrode. This resulted in a self-bias responsible for the decrease in plasma potential.

Interaction of a plasma flow with a magnetic dipole field

The interaction of a streaming plasma with a magnetic dipole field is studied in the framework of a linearized, two-fluid continuum description. For the case of low-density flows, in which the pressure gradients are small in comparison to magnetic and electric forces, it is possible to extend the solution beyond the first-order one, which gives the distribution of induced current in the azimuthal direction, and calculate space-charge density and plasma potential distributions, along with the Hall current components in a restricted spatial region. The quantities of second-order scale directly with the appropriate Cowling number, whereas the azimuthal current density increases with the square root of this ratio. It is also shown that the Hall current densities and potential variation increase rapidly with increasing plasma density, while the normalized space charge density scales with the square of the plasma velocity. Moreover, the theory predicts a significant decrease in plasma potential in the vicinity of the dipole; a result which tends to agree with recent experimental indications.