Xinlu Deng

Characterization of CNx films prepared by twinned ECR plasma source enhanced DC magnetron sputtering

Abstract The DC discharge of a planar magnetron was enhanced by twinned microwave electron cyclotron resonance plasma source. The magnetic cusp geometry formed in the processing chamber was used for plasma confinement. The sputtering discharge characteristics was investigated and a combined mode of voltage and current was observed at a pressure as low as 0.007 Pa. Carbon nitride thin films were synthesized using this method. Characterization of the films showed that the deposition rate was high, and the films were composed of a single amorphous carbon nitride phase with N/C ratio close to that of C3N4, with the bonding mainly of CN type.

The effect of N2 flow rate on discharge characteristics of microwave electron cyclotron resonance plasma

The properties of plasma in Ar/N2 microwave electron cyclotron resonance discharge with a percentage of N2 flow rate ranging from 5% to 50% have been studied in order to understand the effect of N2 flow rate on the mechanical properties of silicon nitride films. N2+ radicals as well as N2, N+ are found by optical emission spectroscopy analysis. The evolution of plasma density, electron kinetic energy, N2+, N2, and N+ emission lines from mixed Ar/N2 plasma on changing mixture ratio has been studied. The mechanisms of their variations have been discussed. Moreover, an Ar/N2 flow ratio of 2/20 is considered to be the best condition for synthesizing a-Si3N4, which has been confirmed in the as-deposited silicon nitride films with quite good mechanical properties by nanoindentation analyses.

ENERGY AND ANGLE DISTRIBUTIONS OF IONS STRIKING A SPHERICAL TARGET IN PLASMA SOURCE ION IMPLANTATION

Plasma source ion implantation is a process in which a target is immersed in a plasma and a series of large negative‐voltage pulses is applied to it to extract ions from the plasma and implant them into the target. A Monte Carlo simulation model is developed to study the energy and angle distributions of ions striking the spherical target for high pressures of the neutral gas. The ion‐neutral charge exchange and momentum‐transfer cross sections that depend on the ion energy are taken into account precisely. The energy and angle distributions of Ar+ at the spherical target during the sheath edge evolution after the ion matrix sheath for different pressures are investigated in detail.

Rotational temperature of nitrogen glow discharge obtained by optical emission spectroscopy.

Measurements of rotational temperature as low as several hundred Kelvin have been measured using optical emission spectroscopy (OES) in nitrogen direct current (DC) glow discharge. The strongest band of the first negative system of nitrogen was chosen to deduce the rotational temperature at four different positions in nitrogen DC glow discharge, the back of cathode; cathode sheath; positive column; and anode glow. In positive column the rotational temperature increased apparently with the increasing discharge voltage from 500 to 1000 V when the pressure was 10 Pa. But with pressure of 20 Pa the rotational temperature in positive column increased slightly with the increase of discharge voltage. On the contrary, the rotational temperature in cathode sheath took reverse tendencies when the discharge voltage varies from 500 to 1000 V. As regard the anode glow, the rotational temperature at 10 Pa decreased with the increase of discharge voltage, but that at pressure of 20 Pa increased. We attribute the different tendencies of the rotational temperature to the different discharge statues at different pressures. When the discharge voltage varies from 500 to 1100 V, the discharge with pressure of 10 Pa is normal glow and that with 20 Pa is abnormal glow.

Model of collisional sheath evolution in plasma source ion implantation

A model is developed to study the temporal evolution of the sheath during a pulse of high negative voltage applied to a target immersed in a plasma, such as that present in plasma source ion implantation. This model covers the whole range from collision free to collision dominated sheaths. The sheath expansion velocity and the position of the sheath edge as a function of time in planar geometries for various pressures are obtained.

Energy and angle distributions of ions striking the spherical target* in plasma source ion implantation

Plasma source ion implantation is a process in which a target is immersed in a plasma and a series of large negative‐voltage pulses are applied to it to extract ions from the plasma and implant them into the target. A Monte Carlo simulation model is developed to study the energy and angle distributions of ions striking the spherical target for high pressures of the neutral gas. The charge exchange and momentum transfer sections of ion‐neutral that depend on the ion energy are taken into account precisely. The energy and angle distributions of A+r at the spherical target during the sheath edge evolution for the different pressures are investigated in detail.

Emission spectrum diagnostics of argon DC discharge

Abstract An experimental setup has been built to carry out DC glow discharge and microwave ECR discharge and to depict the space-resolved emission spectra of the discharges. The setup is characterized by its optical collection system that is capable of being finely displaced. The emission spectra in the visible region of argon DC discharge have been measured to study the relative densities of some species and their response to discharge conditions, such as pressure and DC voltage. Also, the density variation with discharge conditions of some interested species, for example, the excited state Ar ( 2 F 32 ) , has been given extraordinary notice, in order to find out the most suitable situation for more extensive investigation of argon plasma.

An analytic model for energy distributions of neutrals striking a planar cathode at low pressure glow discharges

In this paper, we present a theoretical model for energy distributions of neutrals striking a planar cathode at low pressure glow discharges. An analytic expression of neutral energy distribution at the cathode is deduced. The analytic results are almost identical with Monte Carlo simulation.

INVESTIGATION ON OPTICAL EMISSION SPECTRA DURING ECR PLASMA ENHANCED MAGNETRON SPUTTERING CARBON NITRIDE FILM DEPOSITION

Emission spectra from the ECR plasma enhanced magnetron sputtering discharge used for CNx film deposition were investigated in the wavelength range 350 – 550 nm. The optical emission spectra from both the negative glow discharge zone near the target surface and the plasma zone formed by ECR discharge and magnetron discharge were studied separately. The dominant chemical species in both zone were found to be N2+, N2*, and CN radicals. But the intensity of CN radical in the plasma zone was greater than that in the negative zone, where an emission band of C2 was detected. The dependence of the intensities of CN band on the working gas pressure was investigated, and the formation of CN radicals, which could be vital in the CNx film deposition process, was discussed. It was shown that a possible mechanism could be the reaction of N2+ and N2 with C2 in the gas phase.

Computer controlled plasma source ion nitriding

This paper describes how to realize computer-controlled plasma source ion nitriding (PSIN) and introduces some results of stainless-steel-samples treated by auto-PSIN for the first time.